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SURGEON GENERAL'S WARNING:

Using this grow game gives you insight in how to grow your own. It can lead to very serious time spending, lack of nutrients, poor social life and repetitivo strain injury!

Thé solution for growth and bloom

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Scrog Grow Rockwool

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This Swiss hydroponic setup is simple, efficient, and economical.

Growing Plants Glass Bottles

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Introduction

Hydroponics is the science of growing plants without soil, most often in a soilless mix. In fact, many growers are already cultivating hydroponical-ly. Cultivating clones in rockwool, peat moss, and coconut fiber is growing hydroponically. Growing mature plants in soilless Sunshine Mix or Terra-Lite, even when watered by hand, is hydroponic gardening. With hydroponics, nutrient uptake and grow medium oxygen content can be controlled easily. Manage these two factors, along with a few other requirements, to grow a bumper crop of buds with every harvest,

The inert soilless hydroponic medium contains essentially no nutrients, All the nutrients are supplied via the nutrient solution-fertilizer diluted in water. This solution passes over or floods around roots at regular intervals, later draining off. The extra oxygen trapped in the soilless medium and around the roots speeds nutrient uptake by tiny root hairs. Cannabis grows fast hydroponically, because it is able to take in food as fast as it can be used, in soil, as in hydroponics, the roots absorb nutrients and water. Even the best soil rarely has as much oxygen in it as a soilless hydroponic medium.

Contrary to popular belief, hydroponic gardens often require more care than soil gardens. If growing hydroponically, expect to spend more time in the garden, Extra maintenance is necessary because plants grow faster, there are more things to check, and more can go wrong. In fact, some growers do not like hydroponic gardening, because it requires loo much additional care.

Hydroponic gardening is productive, but exacting-not as forgiving as soil gardening. Soil works as a buffer for nutrients and holds them longer than inert hydroponic growing mediums. In fact, advanced aeroponic systems do not use a soilless mix; they use nothing al all!

In hydroponics, the nutrient solution can be controlled, so plants grow less leafy foliage and more dense flower buds. The stepped-up nutrient control makes plants llower faster and be ready lor harvest a few days earlier than soil-grown cannabis.

Small flowering plants grow well in small hydroponic containers and horizontal tubes. Mother plants grow longer and are best suited lo a large bucket system, which allows room (or root development. The mother plants' root system is easily contained in the bucket, and she is able to produce

_____________„______are grown hydroponically in expanded clay pellets, an inert soilless medium. Plants can take in all the nutrients t/iey need.

thousands of clones during her lifetime. Mother plants must have a huge root system to take in lots of nutrients to keep up with the heavy growth and clone production schedule.

Most grow rooms have two limiting factors: the number of plants in the garden and the electrical consumption expressed in watts. For example, if growing 12 large plants in a five-gallon (19 L) bucket hydroponic system, you will need about ten clones and one mother plant. The flowering room could be illuminated with two 600-watt HP sodium lamps. A 40-watt fluorescent fixture could be used to root clones, and a 175-watt metal halide will keep the mother and vegetative plants growing. This is a total of 1415 watts that cost about $35 to $60 monthly, That's a bargain considering the garden will yield at least a pound (150 gm) of beautiful hydroponic buds every month!

If flowering is induced when clones are six to eight inches (15-20 cm) tall, they will be two to three feet (60-80 cm) tall when they finish flowering. You can pack short plants tightly together in a "sea of green" (SOG) or a "screen of green" (SCROG) to maximize yield. It is easy to grow 60,

St four-inch (10 cm) rockwoo! cubes on a flood and drain table or in three-gallon (11 L) grow bags full of soilless medium, To get the maximum yield, a plant or two is harvested every day or two. When a ripe plant is harvested, two small clones take its place. The weaker clone is culled out after two weeks.

Different Systems

Hydroponic systems are distinguished by the way the nutrient solution is applied. The first distinction is whether the nutrient solution is applied in an "active" or "passive" manner.

Passive systems rely on capillary action to transfer the nutrient solution from the reservoir to the growing medium. Nutrient solution is passively absorbed by a wick or growing medium and transported to the roots. Absorbent growing mediums such as vermiculite, sawdust, peat moss, etc., are ideal for passive systems. The growing medium can stay very wet in passive systems, and substrate selection is important. Soggy substrates hold less air and deprive roots of rapid nutrient uptake. Although passive gardens are not considered "high

Biogreen Marihuana

This flood hydroponic garden, fertilized with Bio-Green, uses a soilless mix heavy in coco peat, All nutrients are supplied by the nutrient solution.

Coco Soilless Mix

This passive wick system uses a soilless mix heavy in coco peat to wick up the nutrient solution. Such low-tech gardens are very productive.

Non Circulating Wick Bed

performance," the Dutch have managed to perfect them and achieve amazing results. Wick systems iiave no moving parts. Seldom does anything break or malfunction. Low initial cost and low maintenance enhance wick systems1 popularity.

Dutch growers line the floor of a room with heavy plastic or pond liner. They fill three-gallon (3 L) pots with an absorbent soilless mix that holds plenty of air. They flood the garden with two to three inches (6-9 cm) of nutrient solution. Roots absorb the nutrient solution in two to five days. No nutrient solution is drained off; it is all absorbed by plants!

One Spanish grower uses passive irrigation to water his garden. He drives a delivery truck and is away Irom home five days a week. He keeps his indoor garden under a 400-watt HPS lamp. The plants are in a rich potting soil, and the pots are in a large tray with four-inch (12 cm) sides. Every Monday morning he fills the tray with mild nutrient solution. When he returns on Friday, the plants are strong and happy!

Active hydroponic systems "actively" move the nutrient solution. Examples of active systems are: flood and drain, and top feed. Cannabis is a fast-growing plant and very well suited to active hydroponic systems.

Active hydroponic gardens are considered a "recovery" system if the nutrient solution is recovered and reused after irrigation. A "non-recovcry" system applies the nutrient solution once, then it runs to waste. The solution is not reused. Non-recovery systems have few complications but are not practical for most cannabis hydroponic gardens. The commercial growers "run-to-waste" systems are avoided, because they pollute ground water with high levels of nitrates, phosphates, and other elements. Indoor growers seldom use non-recovery systems, because they require disposing of so much nutrient solution into the local sewer system.

Active recovery hydroponic systems such as the flood and drain (ebb and flow), top feed, and nutrient film technique (NFT) are the most popular and productive available today. All three systems cycle reused nutrient solution into contact with roots. Recovering and reusing the nutrient solution

Classic wick gardens use cloth wicks that absorb nutrient solution and transport it to the growing medium.

This passive wick system uses a soilless mix heavy in coco peat to wick up the nutrient solution. Such low-tech gardens are very productive.

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HYDROPONIC GARDENING

makes management more complex, but with the proper nutrient Solution, schedule, and a little experience, it is easy to manage. Active recovery systems use growing mediums that drain rapidly and hold plenty of air, including: expanded clay, pea gravel, pumice rock, crushed brick, rockwool, and coconut coir.

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Knowb4ugrowEbb Flow Table Grow Cannabis

Ebb and Flow Gardens

Ebb and flow (flood and drain) hydroponic systems are popular because they have proven track records as low maintenance, easy-to-use gardens. Ebb and flow systems are versatile, simple by design, and very efficient. Individual plants in pots or rockwool cubes are set on a special table. The table is a growing bed that can hold one to four inches (3-10 cm) of nutrient solution. Nutrient solution is pumped into the table or growing bed. The rockwool blocks or containers are Hooded from the bottom, which pushes the oxygen-poor air out. Once the nutrient solution reaches a set level, an overflow pipe drains the excess to the reservoir. When the pump is turned off and the growing medium drains, it draws new oxygen-rich air into contact with the roots. A maze of drainage gullies in the bottom of the table directs runoff solution back to the catchment tank or reservoir. This cycle is repeated several times a day. Ebb and flow systems are ideal for growing many short plants in a Sea of Green garden.

Nutrient solution is pumped up into the bed via the short Hood fixture on the left. The overflow fitting on the right guarantees the nutrient solution will not spill over the top of the table.

Nutrient solution Hoods the growing bed and drains back into a reservoir in an ebb and flow garden.

Self-leveling legs, similar to those of a washing machine, support this ebb and flow garden bed and ensure all plants receive a level dose of nutrient solution and that it all drains back into the reservoir below,

Cannabis Drain Tray

Nutrient solution can be applied from above and the table serves as a drain.

Easy Grow Tables

Growing is easy and efficient in this beautiful Visqueen-lined room.

The grow room is lined with white Visquevn. The grower takes off his shoes to avoid damaging the plastic and to keep the grow show clean.

Flood the table to half to three-quarters the height of the container to ensure even nutrient solution distribution. Avoid lightweight mediums such ¿is perlite that may cause containers to float and fall over.

A large volume of water is necessary to fill the entire table. Make sure the reservoir has enough solution to flood the reservoir and still retain a minimum of 25 percent extra to allow for daily evaporation. Replenish reservoir daily if necessary. Do not let nutrient solution stand in the table for more than a half hour. Submerged roots drown in the depleted oxygen environment.

Flood the table when the medium is about half-lull of moisture. Remember, rockwool holds a lot of moisture. Irrigation regimens will need to change substantially when temperatures cool and light is lacking.

Ebb and flow tables or growing beds are designed to let excess water ilow freely away from the growing medium and roots. When flooded with an inch (3 cm) or more of nutrient solution, the growing medium wicks up the solution into the freshly aerated medium.

Air Table

Air tables are simple, easy-to-use hydroponic gardens. Seasoned growers and novices love their simplicity and low maintenance. The unique oper

Growing is easy and efficient in this beautiful Visqueen-lined room.

The grow room is lined with white Visquevn. The grower takes off his shoes to avoid damaging the plastic and to keep the grow show clean.

Nutrient solution can be applied from above and the table serves as a drain.

Marijuana Flow Table Gardens

This ingenious DWC garden uses an air pump to aerate and agitate the nutrient solution.

Air Tables For Marijuana Growing

The simple ciir table design makes them low maintenance. Air is pumped into a reservoir Tilled with nutrient solution. The air pressure forces the solution up into the growing bed.

Sealed Grow Room Design

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ating principle is simple, effective, and nearly failsafe. The nutrient solution is forced up to the growing bed with air pressure generated by on external air pump. The pump can run on ordinary household electrical current or a solar-powered 12-volt system. Once flooded, the nutrient solution stays in the growing bed for a few minutes before it drains back to the reservoir. Constant air pressure during flooding also aerates the growing medium. The sealed, airtight reservoir limits evaporation, which in turn prevents algae growth and keeps the nutrient fresh. The external pump reduces the overall cost of the system and helps prevent electrical accidents. You can use rockwool, coco coir, peat, or a composite growing medium with excellent results. Check out the Terraponic air table at www.fearless gardener,com,

The simple ciir table design makes them low maintenance. Air is pumped into a reservoir Tilled with nutrient solution. The air pressure forces the solution up into the growing bed.

Deep Water Culture (DWC)

Crowing in deep water culture (DWC) is simple, easy, and productive.

If growing outdoors in a DWC garden, a simple overflow drainage hole can be cut in the side of the reservoir to prevent rainwater from causing it to overllow.

Seedlings and clones are held in net pots full of expanded clay pellets, rockwool or other growing medium. The net pots are nestled in holes in a lid that covers the reservoir. The roots of seedlings and cuttings dangle down into the nutrient solution. A submersible pump lifts nutrient solution to the top of a discharge tube wiiere it splashes into the access lid. Nutrient solution cascades down, wetting roots and splashing into the self-contained reservoir below, which in turn increases dissolved oxygen in the solution. Roots easily absorb nutrients and water from the solution in the oxygenated environment. Many gardens also keep an air stone bubbling new air into the reservoir to supply more oxygen.

These gardens are simple by design and require no timer, because the pumps are on 24 hours a clay. This low-maintenance garden is perfect for casual gardeners as well as liydroponic enthusiasts.

This ingenious DWC garden uses an air pump to aerate and agitate the nutrient solution.

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Cutaway of the inside of a DWC garden

Nutrient Solution

An array of different emitters connected to a main manifold shows the many different kinds of emitters available to hydroponic gardeners. Across the bottom are three different diameters of spaghetti tubes that dispense three different volumes of nutrient solution to plants.

Always use a filter when using emitters. The filter will remove foreign objects that plug emitters.

This emitter sprays nutrient solution over the top of the growing medium to aerate and disperse it evenly.

Circular Hydroponic Weed

Mini sprinkler emitters are available in many sizes and outputs.

B4u Pictures Flowers
Circular emitters apply nutrient solution all the way around the plant, so all roots receive adequate moisture,

An array of different emitters connected to a main manifold shows the many different kinds of emitters available to hydroponic gardeners. Across the bottom are three different diameters of spaghetti tubes that dispense three different volumes of nutrient solution to plants.

Various emitters are available to apply nutrient solution. A single application point is common when growing in absorbent growing mediums such as rockwool and coco coir. Expanded clay works best when nutrient solution is applied via a large round emitter, several single emitters, or a spray emitter.

Pressure regulated drip emitters control solution flow.

This emitter sprays nutrient solution over the top of the growing medium to aerate and disperse it evenly.

Mini sprinkler emitters are available in many sizes and outputs.

Always use a filter when using emitters. The filter will remove foreign objects that plug emitters.

Top-Feed Systems

Top-feed hydroponic systems arc very productive, easy to control, precise, easy to maintain, and efficient. The nutrient solution is metered out in specific doses and delivered via spaghetti tubing or an emitter placed at the base of individual plants. Aerated nutrient solution flows into the growing medium and is taken up by roots. The runoff nutrient solution is directed back to the reservoir as soon as it drains from the growing medium. Rockwool, gravel, coconut coir, and expanded clay are the most common growing mediums found in top-feed systems. Versatile top-feed systems can be used with individual containers or slabs in individual beds or lined up on tables.

Top-feed systems come in many configurations. Systems with several gallons of growing medium are best lor growing large plants that may require support. Small containers are perfect for smaller plants.

Top-Feed Buckets

Self-contained top-feed buckets consist of a growing container nested inside a reservoir containing a pump. Individual buckets make culling out and replacing a sick plant quick and easy. Self-contained top-feed bucket systems are also perfect for growing large mother plants. The container can be moved anywhere easily. Some containers have a net pot suspended in the lid of a five-gallon (19 L) bucket/reservoir. The roots hang down into the reservoir. An air stone in the bottom of the reservoir aerates the nutrient solution. A separate pump cycles the irrigation to the container. Other self-contained top-feed buckets use a large growing container filled with expanded clay pellets. A pump constantly cycles nutrient solution in the system, aerating the solution and irrigating the plant. Roots grow down into the nutrient solution to form a mass on the bottom. Irrigation from the top circulates aerated nutrient solution and flushes out old oxygen-poor solution. Some systems contain a one-inch (3 cm) pipe to draw air directly down to the root zone. There are many different variations of this system, and they all work!

Plant Resevoir Filled HoseB4u Pictures Flowers
The grower plants three well-rooted cuttings in each container.

Multiple Bucket Top-Feed

Other top-feed bucket systems employ multiple buckets that are connected to a main reservoir. A flexible drain hose is attached near the bottom of the bucket/reservoir. The hose is connected to a drainage manifold that shuttles runoff nutrient solution back to a central reservoir.

Each reservoir below the growing container holds an inch or two of water. It is important to regularly cycle irrigation in these gardens, so the solution in the bottom of the buckets does not stagnate.

Top-feed buckets can also be lined up on a drainage table. Square containers make most efficient use of space. Plants are fed with irrigation tubing attached to a manifold. Once delivered, the nutrient solution flows and percolates through the growing medium. Roots take in the aerated nutrient solution before it drains onto the tray and back to the reservoir.

These top feed buckets filled with hydroclay are all set up and ready to be planted. More hydroclay will be added when cfones ere transplanted,

B4u Pictures Flowers
Containers are irrigated with spaghetti tubes attached to a manifold that runs between the rows. Excess nutrient solution drains out the bottom and is directed back to the reservoir via a drain tube.
Marijuana Bucket System

Tills cutaway of a top-feed bucket system shows how roots dangle in a 100 percent humid environment before growing into the nutrient solution. Remember to screen the drain in the reservoir so roots do not block it.

Individual containers in top-feed bucket systems are easy to arrange to fit into the allotted garden space. Plants can also be transplanted or removed from pots and cared for individually.

Top-Feed Slabs

Overview

Top-feed slab systems are popular among small and large indoor and greenhouse growers. Rockwool or coco slabs covered in plastic serve as growing containers. The nutrient solution is delivered via spaghetti tubes from the top of the slab. An emitter attached to the spaghetti tube doses a specific measure of nutrient solution to each plant. The nutrient solution is aerated as it is applied, before being absorbed by the growing medium and draining back to the reservoir.

A simple nutrient solution delivery manifold consists of emitters connected to spaghetti delivery tubes. The tubes are attached to a short manifold that is fed by a pump submerged in a reservoir.

Emitters are designed to be anchored in growing medium and to emit a measured dose of nutrient solution.

Slabs in individual trays

Some systems use individual trays to contain slabs. Nutrient solution is pumped from the reservoir and delivered to plants via spaghetti tubes attached to emitters. Individual trays are easy to configure for different sized gardens. Tables of slabs

You can also set up a drainage table and place slabs on top. The nutrient solution is pumped from the reservoir below the table and delivered to individual plants via spaghetti tubes attached to emitters. The solution flows into the growing medium vyhere it comes into contact with roots. Excess nutrient solution drains from pots onto the table and is carried back to the reservoir. Make sure the table is set up on an incline so it drains evenly. Pockets of standing water on (he table contain less oxygen and promote rot. Individual Blocks

Individual blocks in this rockwool system allow gardeners the possibility of removing or changing plants if necessary. Nutrient solution is pumped via in

Canna Coco Medium Slab

Nutrient solution from this hot of Canna coco drains into an open trough and is carried back to the reservoir. Salt buildup from the nutrient solution is easy to scrub out of the open trough.

Tube Fluorescent Pour Cultiver Cannabis

Top-feed slabs of rockwool fit in individual containers. Spaghetti tubes irrigate pfants from the top.

Spaghetti Irrigation System NftCommercial Ebb And Flow Marijuana

Ebb and flow tables catch nutrient solution runoff and direct it back to the reservoir.

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Nutrient solution from this hot of Canna coco drains into an open trough and is carried back to the reservoir. Salt buildup from the nutrient solution is easy to scrub out of the open trough.

Top-feed slabs of rockwool fit in individual containers. Spaghetti tubes irrigate pfants from the top.

spaghetti tubes from the reservoir below and distributed via emitters pressed into rockwool cubes.

Vertical Top-Feed Systems

Vertical gardens can increase overall yield more than ten-fold over a flat garden. Substrate bags, tubes, or slabs are positioned vertically around an HID. Short plants are placed in the medium and fed individually with a drip emitter. The runoff drains through the growing medium and back to the reservoir. The solution is re-circulated once it returns to the reservoir.

This cutaway drawing shows how nutrient delivery is simple and easy with a top-feed bat system. Aerated nutrient solution is metered via emitter onto a grow cube. Aerated solution percolates down through the medium. Channels in the bottom of the tray speed drainage back to the reservoir.

Ebb and flow tables catch nutrient solution runoff and direct it back to the reservoir.

Compact Fluorescent Bulbs Marijuana
This new vertical garden uses rackwool as a growing medium and compact fluorescent lamps.

Use rockwool or coco mixed wilh lightweight ver-micuiite as a growing medium to lessen weight when substrate is wet. Irrigate constantly to keep roots supplied with water and nutrients from a well-aerated solution.

Vertical hydroponic systems save space, but require more maintenance. These systems can also be tricky to fine-tune so they operate at peak capacity.

Nutrient Film Technique (NFT) hydroponic systems are high performance gardens that perform well when fine-tuned. This relatively new form of hydroponics supplies aerated nutrient solution to roots located in gullies, Seedlings or cuttings with a strong root system are placed on capillary matting located on the bottom in a covered channel. The capillary matting stabilizes nutrient solution How and holds roots in place. Constantly aerated nutrient solution flows down the channel, or gully, over and around the roots, and back to the reservoir. Irrigation is most often constant, 24 hours a day. Roots receive plenty of oxygen and are able to absorb a maximum of nutrient solution. Proper gully incline, volume, and flow of nutrient solution are key elements in NFT gardens.

Gullies or channels are covered to keep humidity high in the root zone and light from shining on roots, Root hairs responsible for most water and nutrient uptake cover the growing tips of advancing roots. These roots are submerged in turbulently flowing nutrient solution and the tops are intermittently in humid air. The nutrient solution is constantly aerated as it flows down the inclined gulley. The slope of the gulley is adequate to prevent water from stagnating. Often a filter is necessary to prevent debris from blocking gullies and pump.

Although high performance, NFT systems offer practically no buffering ability. In the absence of a growing medium, roots must be kept perfectly moist by the nutrient solution at all times. If a pump fails, roots dry and die. If the system dries out for a day or longer, small feeder roots will die and grave consequences will result, The system is very easy to clean and lay out after each crop, Only growers with several years experience should try an NFT system if working alone. With help, they are easier to master.

Double reinforced bottom makes gullies durable and rigid when supporting large plants, root systems, and large volumes of nutrient solution. Some NFT gullies have ribs below to provide support and prevent warping and movement. The ribs also function as drainage channels and direct nutrient solution evenly along the bottom of the gully.

Many NFT systems are hybrids. For example, the nutrient solution in some hybrid NFT systems is delivered via spaghetti tubing to each plant. More irrigation sites help each plant receive proper irrigation, The nutrient solution flows through a small basket of growing medium before it runs down the gulley, over the roots, and back to the reservoir. Yet another hybrid NFT system employs spray nozzles inside the gulley. The nozzles spray nutrient solution on and around roots to keep the root zone environment at 100 percent humidity. The nutrient solution flows down a PVC pipe, over roots, and back to the reservoir.

* Too often, these hybrid systems are poorly planned and designed. Many times they are constructed from white four-inch PVC pipe. The thin white walls of the PVC pipe allow enough light to illuminate roots that they turn green or rot more easily. I have also seen systems with nozzles inside the PVC pipe. If a nozzle plugged inside the pipe, there was no easy way to access the nozzle for maintenance.

iYDROPONIC GARDENI!

Nft Cannabis

Nutrient solution in this hybrid NFT system is delivered via nozzles attached to a PVC pipe Inside the main growing tubes.

Cullies with rounded comers are very popular in Australia. Growers who use them say the nutrient solution flows more smoothly.

Pvc Pipe Grow Pot

Many gu/lles are flat on the bottom. Capillary matting is placed on the bottom under the growing cubes. The capillary matting anchors roots and helps direct nutrient solution evenly over roots.

Stagnant nutrient solution and salt buildup stifle root development Soon roots turn dark and rot. Note burned and discolored leaves that signify salt buildup.

Cullies with rounded comers are very popular in Australia. Growers who use them say the nutrient solution flows more smoothly.

Nutrient solution in this hybrid NFT system is delivered via nozzles attached to a PVC pipe Inside the main growing tubes.

Many gu/lles are flat on the bottom. Capillary matting is placed on the bottom under the growing cubes. The capillary matting anchors roots and helps direct nutrient solution evenly over roots.

Aeroponics

Aeroponic systems use no growing medium and offer the highest performance possible. Roots are suspended in a dark growth chamber without growing medium where they are misted with oxygen-rich nutrient solution at regular intervals. The humidity in the chamber remains at or near 100 percent 24 hours a day. Roots have the maximum potential to absorb nutrient in the presence ol air.

Small net pots are preferred for most NFT systems. Larger net pots are used in NFT systems as well as top-feed hydro-panic systems.

Stagnant nutrient solution and salt buildup stifle root development Soon roots turn dark and rot. Note burned and discolored leaves that signify salt buildup.

Nutrient solution is pumped from the reservoir into gullys via a manifold and tubing at the upper end. The table is set up on an incline so the nutrient solution flows quickly over roots to create an environment packed with air and available nutrients, A catchment drain directs the nutrient back into the nutrient reservoir.

Marijuana Root System

Long root systems develop quickly on cuttings in this Rain Forest acroponic system.

Marijuana Aeroponic Root Rot

Rooted clones and seedlings grown in aeroponic systems develop exceptionally fast To grow clones, simply insert clone stems into the growth chamber and turn it on. The roots will grow in a perfect environment to develop roots.

Mini Dwc Harvest

Roots in this NFT system are strong and healthy. This system produced a heavy harvest of buds on robust plants.

Long root systems develop quickly on cuttings in this Rain Forest acroponic system.

Rooted clones and seedlings grown in aeroponic systems develop exceptionally fast To grow clones, simply insert clone stems into the growth chamber and turn it on. The roots will grow in a perfect environment to develop roots.

Growing Mediums

Soilless growing mediums provide support for the root system, as well as hold and make available oxygen, water, and nutrients. Three factors contribute to cannabis roots' ability to grow in a substrate: texture, pH, and nutrient content, which is measured in EC, electrical conductivity.

The texture of any substrate is governed by the size and physical structure of the particles that constitute it. Proper texture promotes strong root penetration, oxygen retention, nutrient uptake, and drainage. Growing mediums that consist of large particles permit good aeration and drainage. Increased irrigation Irequency is necessary to compensate for low water retention. Water- and airholding ability and root penetration are a function of texture. The smaller the particles, the closer they pack together and the slower they drain. Larger particles drain faster and retain more air.

Irregular shaped substrates such as perlile and some expanded clays have more surface area and hold more water than round soilless mediums. Avoid crushed gravel with sharp edges that cut into roots if the plant falls or is jostled around. Round

Humid air and nutrient solution are all that lill the growth chamber. Plants are most often grown in net pots full of growing medium and suspended from the top of the system,

Aeroponic systems require greater attention to detail. There is no growing medium to act as a water/nutrient bank, which makes the system delicate and touchy to use. If the pump fails, roots soon dry, and plants suffer. Systems that use delicate spray nozzles must be kept free of debris. Imbalanced nutrient solution and pH can also cause problems quickly. This is why it is important to purchase quality components or a ready-made system from a qualified supplier.

The RainForest (www.generalhydroponics.com) is very popular. Nutrient solution is actually atomized into the air creating 100 percent humidity. Nutrient solution is dripped onto a spinning plate. The solution atomizes, mixing with the air as it spins off the plate. The spinning plate is located above the water in the reservoir.

Roots in this NFT system are strong and healthy. This system produced a heavy harvest of buds on robust plants.

rrnETai¥j=i pea gravel; smooth, washed gravel; and lava rocks are excellent mediums to grow marijuana in an active recovery system. Thoroughly wash clay and rock growing mediums to get out alt the dust that will turn to sediment in your system.

Fibrous materials like vermiculite, peat moss, rockwool, and coconut coir retain large amounts of moisture within their cells. Such substrates are ideal for passive hydroponic systems that operate via capillary action.

Mineral growing mediums are inert and do not react with living organisms or chemicals to change the integrity of the nutrient solution. Coconut coir and peat mosses are also inert.

Non-inert growing mediums cause unforeseen problems. For example, gravel from a limestone quarry is full of calcium carbonate, and old concrete is full of lime. When mixed with water, calcium carbonate will raise the pH, and it is very difficult to make it go down. Crowing mediums made from reconstituted concrete bleed out so much lime, they soon kill the garden.

Avoid substrates found within a few miles of the ocean or large bodies of salt water. Most likely, such mediums are packed with toxic salts. Rather than washing and leaching salts from the medium, it is easier and more economical to find another source of substrate.

Air is a great medium when it is filled with 100 percent humidity 21 hours a day.

Coconut fiber is an excellent hydroponic medium. See "Coconut Fiber" under soil amendments. Hit the site www.canna.corn .for detailed information about growing marijuana in coconut fiber.

Expanded clay, also called hydroclay, or hydrocorn, is made by many different manufacturers. The clay pellets are cooked at high temperatures in a kiln until they expand. Many little catacomb-like pockets form inside each pellet that holds air and nutrient solution. It is an excellent medium to mix with Peat-Lite and to grow mothers in large containers. I like the way it drains so well and still retains nutrient solution while holding lots of oxygen. Examples of expanded clay includc commercially available Hydroton, Leca, Grorox, Geolite.

Expanded clay holds moisture and nutrients along with tots of oxygen.

Marijuana Drying Kiln

Expanded clay holds moisture and nutrients along with tots of oxygen.

Marijuana Drying KilnMarijuana Drying KilnMarijuana Drying Kiln

Artificial foam slabs are used by some growers. To date they are still gaining popularity.

Growing Cannabis Inside Container

Grow Rocks

Some clay pellets will float.

Expanded clay can be reused again and again. Once used, pour expanded clay pellets into a container and soak in a sterilizing solution ol ten milliliters hydrogen peroxide per four liters of water. Soak for 20-30 minutes. Remove expanded clay and place on a screen of hardware cloth. Wash and separate clay pellets from dead roots and dust Let dry and reuse.

Expanded mica is similar to expanded clay. For lots of exacting Information on how and why this stuff works so well, check out www.hydroponics.com.

Foam is somewhat popular, it lasts a long time, lends itself to easy sterilization, and holds a lot of water and air.

Gravel is one of the original hydroponic mediums, Although heavy, gravel is inert, holds plenty of air, drains well, and is inexpensive. Still popular today, gravel is difficult to overwater. It holds moisture, nutrient, and oxygen on its outer surfaces. Use pea gravel or washed river gravel with round edges that do not cut roots when jostled about. Grave! should be 0.125-0.375-inches (3-10 mm) in diameter, with more than half of the medium about 0.25-inch (6 mm) across. Crushed rock can be packed with many salts, Pre-soak and adjust its pH before use. Gravel has low water retention and low buffering ability.

Pumice is a naturally occurring, porous, lightweight, volcanic rock that holds moisture and air in catacomb-like surfaces. Light and easy to work with, some lava rock is so light it floats. Be careful that sharp ed^es on the rocks do not damage roots. Lava rock is still a good medium and acts similarly to expanded clay. See "Pumice11 under "Soil Amendments."

Peat moss is partially decomposed vegetation. Decomposition has been slow in the northern regions where it is found in bogs. There are three common kinds of peat moss-Sphagnum, Hypnum, and Reed/Sedge. Sphagnum peat is about 75 percent fiber with a pH of 3 to 4. Hypnum peat is about 50 percent fiber with a pH of about 6. Reed/sedge peat is about 35 percent fiber with a pH of six or more. For more information see "Soil Amendments" in Chapter Ten.

Perlite drains fast, but it's very light and tends to float when flooded with water. Perlite has no buffering capacity and is best used to aerate soil or soilless mix. See "Soil Amendments" in Chapter Ten.

Rockwool is an exceptional growing medium and a favorite of many growers. It is an inert, sterile, porous, non-degradable growing medium that provides firm root support. Rockwool

Perlite is sand or volcanic glass expanded by heal See Chapter Ten for more information.

Pumice is a good growing medium, tt can also be used as mulch or as an inert soil amendment.

Peat moss mixed with perlite is one of the all-time favorite growing mediums. It is also an excellent soil amendment.

Artificial foam slabs are used by some growers. To date they are still gaining popularity.

Soilless grow medium.

er TWELVE

Mia r. t has the ability to hold water and air for the roots. The roots are able to draw in most of the water stored in the rockwool, but it has no buffering capacity and a high pH. Rockwool is probably the most popular liydroponic growing medium in the world. Popular brand names include Grodan, HydroGro and Vacrok.

Sand is heavy and has no buffering ability. Some sand has a high pH. Make sure to use sharp river sand. Do not use ocean or salty beach sand. Sand drains quickly but still retains moisture. Sand is best used as a soil amendment in volumes of less than ten percent.

Sawdust holds loo much water for marijuana growth and is usually too acidic. Be wary of soils with too much wood matter. Such mediums use available nitrogen to decompose the leglin in the wood.

Vermiculite holds a lot of water and is best suited for rooting cuttings when it is mixed with sand or perlite. With excellent buffering qualities, vermiculite holds lots of water and has traces of magnesium (Mg), phosphorus (P), aluminum (Al), and Silicon (Si). Do not use construction grade vermiculite which is treated with phytotoxic chemicals. See "Soil Amendments" in Chapter Ten for more information.

Water alone is a poor medium, because it cannot hold enough oxygen to support plant life. When aerated, water becomes a good growing medium.

The pH of the nutrient solution controls the availability of ions that cannabis needs to assimilate. Marijuana grows well hydroponically within a pH range of 5,5-6.5, with 5,8-6.0 being ideal. The pH in hydroponic gardens requires a somewhat vigilant eye. In hydroponics, the nutrients are in solution and more available than when in soil. The pH of the solution can fluctuate a half point and not cause any problems.

Roots take in nutrients at different rates, which causes the ratios of nutrients in solution to change the pH. When the pH is above 7 or below 5.5, some nutrients are not absorbed as fast as possi-

Rockwool cubes hold plenty of air and nutrient solution within their fiber; plus, they are clean and easy to use.

Soilless grow medium.

Vermiculite holds a lot of nutrient solution.

This chart shows the porosity and air space available in different substrates.

Substrate Porosity AirSpace

Coconut fiber

90%

10%

Peat:/Vermiculite

88%

9%

Peat:/Perlite

78%

15%

Peat:/Rockwool

88%

14%

Peat moss

90%

15%

Perlite

68%

30%

Rockwool

90%

20%

Sand

38%

3%

Vermiculite

80%

10%

MARIJUANA HORTICULTURE The Indoor/Outdoor MEDICAL GROWER'S BIBLE

Adjust nutrient solution pH level up with:

Buy pH Up and pH Dawn rather than making your own from concentrated acids. Commercial mixes are buffered and safe to use.

Perfect Level For Canabis

Adjust nutrient solution pH level down with:

pH Down

Nitric acid Phosphoric acid Citric acid Vinegar

Buy pH Up and pH Dawn rather than making your own from concentrated acids. Commercial mixes are buffered and safe to use.

Adjust nutrient solution pH level up with:

pH Up

Potassium hydroxide Do not use dangerous and caustic sodium hydroxide to raise pH.

Adjust nutrient solution pH level down with:

pH Down

Nitric acid Phosphoric acid Citric acid Vinegar ble. Check the pH every day or two to make sure it is at or near the perfect level.

Deviations in pH levels often affect element solubility. Values change slightly with different plants, grow mediums, and hydroponic systems. Overall, hydroponic gardens require lower pH levels than that of soil. The best pH range for hydroponic gardens is from 5.5 to 6,5. Different mediums perform best at different pl-l levels. Follow manufacturer's guidelines for pH level, and correct the pl-l using the manufacturer's suggested chemicals, because they will react best with their fertilizer.

The pH can easily fluctuate up and down one full point in hydroponic systems and cause little or no problem with nutrient uptake.

Follow the directions on the container, and remember to mix adjusters into the reservoir slowly and completely. Fertilizers are normally acidic and lower the pH of the nutrient solution. But nutrient solution is still taken in by plants, and water transpires and evaporates into the air, which causes the pH to climb.

Stabilize the pH of the water before adding fertilizer.

Make a correction il readings vary ± one-half point.

This controller monitors and controls the pH in the reservoir by dispersing pH Up or pH Down. The separate thermometer/hygrometer on top of the controller in the photo monitors ambient temperature and humidity.

EC METERS

Pure distilled water lias no resistance and conducts no electrical current. When impurities are added to pure distilled water in the (orm of fertilizer salts, it conducts electricity, A water analysis will indicate the impurities or dissolved solids found in household tap water. These impurities conduct electricity.

Nutrient (salt) concentrations are measured by their ability to conduct electricity through a solution. Dissolved ionic salts create electrical current in solution. The main constituent of hydroponic solutions is ionic salts. Several scales are currently used to measure how much electricity is conducted by nutrients including: Electrical Conductivity (EC), Conductivity Factor (CF), Parts Per Million (ppm), Total Dissolved Solids (TDS), and Dissolved Solids (DS). Most American growers use ppm to measure overall fertilizer concentration. European, Australian, and New Zealand growers use EC, however they still use CF in parts of Australia and New Zealand. Parts per million is not as accurate or consistent as EC to measure nutrient solution strength.

The difference between EC, CF, ppm, TDS, and DS is more complex than originally meets the eye. Different measurement systems all use the same base, but interpret the information differently. Let's start with EC, the most accurate and consistent scale.

Electrical conductivity is measured in milliSiemens per centimeter (mS/cm) or microSiemens per centimeter (pS/cm). One microSiemen/cm = 1000 milliSiemens/cm.

Parts per million testers actually measure in EC and convert to ppm. Unfortunately, the two scales (EC and ppm) are not directly related. Each nutrient or salt gives a different electronic discharge reading. To overcome this obstacle, an arbitrary standard was implemented which assumes "a specific EC equates to a specific amount of nutrient solution." Consequently, the ppm reading is not precise; it is only an approximation, a ball park figure! It gets more complex! Nutrient tester manufacturers use different standards to convert from EC to the ppm reading.

ABOVE LEFT; The probe of this meter is submerged in (he nutrient solution to monitor pH 24 hours a day.

ABOVE RIGHT: Constant readout, temperature-compensated EC/ppm meters with a probe immersed in the nutrient tank provide round-the-clock intelligence.

RIGHT: This quick-dip Thruegeon measures EC quickly and efficiently. It was one of the first accurate, economical EC meters that was easy (o use.

Every salt in a multi-element solution has a different conductivity factor. Pure water will not conduct electrical current, but when elemental salts/metals are added, electrical conductivity increases proportionately. Simple electronic meters measure this value and interpret it as total dissolved solids (TDS). Nutrient solutions used

EC = Electrical Conductivity CF = Conductivity Factor PPM = Parts Per Million TDS - Total Dissolved Solids DS = Dissolved Solids il

-SOD

MARIJUANA HORTICULTURE The Indoor/Outdoor MEDICAL GROWER'S BIBLE

Parts per million recommendations are inaccurate and confusing. To help you through this confusion, an Australian friend compiled the following easy reference conversion chart

Conversion scale from ppm to CF and EC. EC Hanna Eutech Truncheon CF mS/cm O.Sppm 0.64ppm 0.70ppm 0

0.1

50

64

70

01

0.2

100

128

140

02

0.3

150

192

210

03

0.4

200

56

280

04

0.5

250

320

350

05

0.6

300

384

420

06

0.7

350

448

490

07

0.8

400

512

560

08

0,9

450

576

630

09

1.0

500

640

700

10

1.1

550

704

770

11

1.2

600

768

840

12

1.3

650

832

910

13

1.4

700

896

980

14

1.5

750

960

1050

15

1.6

800

1024

1120

16

1.7

850

1088

1190

17

l.B

900

1152

1260

18

1.9

950

1260

1330

19

2.0

1000

1280

1400

20

2.1

1050

1344

1470

21

2.2

1100

1408

1540

22

2.3

1150

1472

1610

23

2.4

1200

1536

1680

24

2.5

1250

1600

1750

25

2.6

1300

1664

1820

26

2.7

1350

1728

1890

27

2.8

1400

1792

I960

28

2.9

1450

1856

2030

29

3.0

1500

1920

2100

30

3.1

1550

1984

2170

31

3.2

1600

2048

2240

32

to grow marijuana generally range between !500 and 2000 ppm. If the solution concentration is too high, the internal osmotic systems can reverse and actually dehydrate the plant. In general, try to maintain a moderate value of approximately 800 to 1200 ppm.

Nutrient solution concentration levels arc affected by nutrient absorption by roots and by water evaporation. The solution weakens as plants use nutrients, but water also evaporates from the solution, which increases the nutrient concentration. Adjust the concentration of the solution by adding fertilizer or diluting with more water.

Many factors can alter the EC balance of a solution. For example, if under-watered or allowed to dry completely, the EC reading will rise. In fact, the EC may increase to two- or three-times as high as the input solution when too little water is applied to rockwool. This increase in slab EC causes some nutrients to build up faster than others. When the EC doubles, the amount of sodium can increase as much as four- to six-fold under the right conditions! There should not be any sodium present in your

Parts per million meters measure the overall level of dissolved solids or fertilizer salts. Each fertilizer sail conducts different quantities of electricity. Use a calibrating solution that imitates the fertilizer in the nutrient solution to calibrate ppm or EC meters. Using such a solution ensures the meter readings will be as accurate as possible. For example, 90 percent of ammonium nitrate dissolved in water is measured, and a mere 40 percent of the magnesium is measured! Do not use sodium-based calibration solutions. They are intended for other applications than gardening. Purchase calibrating solu-lion from the manufacturer or retailer when you buy the meter. Ask for a stable calibrating solution that mimics your fertilizer. Calibrate EC and ppm meters regularly. A good combination ppm, EC, pH meter that compensates for temperature costs about S200 and is well worth the money. Batteries last a long time, too.

LMjE

TWELVE

garden unless ¡1 is in llie water supply, and it should not be in excess of SO ppm.

Lei 10-20 percent of the nutrient solution drain from the growing medium after each irrigation cycle to help maintain EC stability. The runoff carries away any excess fertilizer salt buildup in the growing medium.

If the EC level of a solution is too high, increase the amount of runoff you create with each flush. Instead of a 10-20 percent runoff, flush so 20-30 percent of the solution runs off. To raise the EC, add more fertilizer to the solution, or change the nutrient solution.

A dissolved solids (D5) measurement indicates liow many parts per million (ppm) of dissolved solids exist in a solution. A reading of 1800 ppm means there are 1800 parts of nutrient in one million parts solution, or 1800/1,000,000.

An EC meter measures the overall volume or strength of elements in water or solution. A digital LCD screen displays the reading or the EC of the electrical current flowing between the two electrodes. Pure rainwater has an EC close to zero. Check the pH and EC of rainwater to find out if it is acidic (acid rain) belore using it.

Distilled bottled water from the grocery store often registers a small amount of electrical resistance, because it is not perfectly pure. Pure water with no resistance is very difficult to obtain and not necessary for a hydroponic nutrient solution.

Electrical conductivity measurement is temperature-sensitive and must be factored into the EC reading to retain accuracy. High-quality meters have automatic and manual temperature adjustments. Calibrating an EC meter is similar to calibrating a pl-l meter. Simply follow manufacturer's Instructions. For an accurate reading, make sure your nutrient solution and stock solution are the same temperature.

Inexpensive meters last for about a year, and expensive meters can last lor many years. However, the life of most EC meters, regardless of cost, is contingent upon regular maintenance. The probes must be kept moist and clean at all times. This is the most important part of keeping the meter in good repair. Read instructions on care and mainte nance. Watch for corrosion buildup on the probes of your meter. When the probes are corroded, readings will not be accurate.

To check the EC of the nutrient solution, collect samples from both the reservoir and the growing medium. Save time and effort; collect EC and pl-l samples simultaneously. Collect samples with a syringe or baster at least two inches deep into the rockwool and coco. Collect separate sample from the reservoir. Place each sample in a clean jar. Use calibrated EC meter to measure the samples. Under normal conditions, the EC in the slab should be a little higher than the nutrient solution in the reservoir. If the EC of the solution drawn from the growing medium Is substantially higher than the one from the reservoir, there is a salt buildup in the substrate. Correct the imbalance by flushing substrate thoroughly with diluted nutrient solution, and replace with new solution. Regularly check the EC of your water, slab, and runoff.

Sterilizing

To reuse a growing medium, it must be sterilized to remove destructive pests and diseases. Sterilizing is less expensive and often easier than replacing the growing medium. Sterilizing works best on rigid growing mediums that do not lose their shape such as gravel, expanded clay, and mica. Avoid sterilizing and reusing substrates that compact and lose structure such as rockwool, coconut coir, peat moss, perlite, and vermiculite, Avoid problems caused by compaction and dead roots by replacing used growing mediums. Once sterilized, the medium is free of harmful microorganisms including bacteria and fungi, plus pests and their eggs.

Remove roots from the growing medium before sterilizing. A three- to four-month-old marijuana plant has a root mass about the size of an old desk telephone. Separate the medium by shaking and pulling roots away. Bounce the medium on a screen so roots come to the top. Scoop up and remove roots by hand. Fewer decaying roots cause fewer pest and disease problems, and decrease incidence of clogged feeder tubes.

Peak Harvest Cannabis

Remove harvested plant root balls from the growing medium, and remove roots and stems.

Cannibus Root Pests

Substrate can also be washed in a large container such as a barrel or bathtub. Washing works best with lighter substrates such as expanded clay or mica, Roots float to the top and are readily skimmed off with a screen or by hand.

Once roots are removed, soak the substrate in a sterilant such as a five percent laundry blcach (calcium or sodium hypochlorite) solution for at least an hour. Or mix hydrochloric acid, the kind used in hot tubs and swimming pools. Pour, drain, or pump off the sterilant, and flush the medium with plenty of fresh water. A bathtub and a shower nozzle on a hose are perfect for washing substrate. Place the substrate in the bathtub, set a screen over the drain, and use the shower-head or a hose to wash down the medium. It may be necessary to fill the tub with fresh water and drain it a couple of times to rinse any residual sterilants from the substrate,

If you decide to use rockwoo! or coco a second time, you may have problems with pests and diseases. In general, I recommend reusing a medium only if it

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Responses

  • muhammed
    How to control nutrient runoff in cannabis plant?
    6 years ago
  • dale hay
    How to tell when marijuana is ready to harvest?
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