Marijuana Horticulture

ém lightweight and seemed very bright when the lights were turned on.

Clones were potted and placed on the benches (ten under each lamp). For the first five or six days, the lights were kept about one meter above the plants, then gradually lowered to about half that height as growth became healthy and vigorous. Watering was done by hand, and because the soil was a premixed organic blend, no extra fertilizer was added for the first week.

Nigel and Terry hovered over this first crop like proud fathers. They adhered to a daily schedule of watering, monitoring pH, and inspecting leaves for signs of insect attack and nutrient imbalance. As a result, the plants developed quickly and were ready to begin flowering by the end of the second week. To induce flowering, the lights were set back from 18 to 12 hours per day. About this time, they began to add organic nutrient supplements to the daily soak. As the plants developed further, they worked up quite a thirst; all pots were watered until their individual drip trays nearly overflowed.

The carbon filter was connected around week 6, in an effort to prevent odors escaping the shed. This tactic worked well, but it reduced airflow. As the plants increased in size and density, it became increasingly difficult to keep grow room temperatures below 86°F (30°C). On a couple of occasions, the temperature rose above 91QF (33°C), and bud development definitely suffered. The guys remember one time when every plant stopped growing for three or four days after the room overheated.

As their crop approached maturity, Nigel and Terry noticed something strange going on. Most plants were finishing off nicely, but some (generally the biggest) didn't seem to be maturing properly. The buds on the plants growing right under the lamps were big but didn't seem as solid or as resinous as those on the other plants. This condition became more noticeable as time progressed. By the 8-week mark, the larger plants started to go a bit yellow and drop leaves.

It was time to pull the pin on this caboose!

The crop was harvested a few days later and hung to dry. In general, the smaller plants produced better quality buds than the larger plants. The yield was 8,4 pounds (3.8 kg) of very nice weed, and with that in hand, who was going to complain?

Actually, the boys were very happy with their first result, as everything ran quite smoothly. They had a few problems with heat, but they learned a lot and gained the confidence (and the $) to expand their room to its full potential, 33 feet x 10 feet <10 * 3 m).


This was a time of change and serious improvement. Over the past three months, Nigel and Terry had visited the local hydro store on many occasions and had struck up a friendship with one of the owners who worked there. He had given them heaps of useful advice, and the boys realized that without his input, the first crop could have easily ended in failure.

The storeowner (we'll call him Bob) offered to help the boys design their new double-sized room, provided they purchase all their new equipment from him, of course. He insisted that the system they were currently running used too much power, generated too much heat, and was too labor-intensive to be successfully doubled in size and maintained by two guys already working full-time jobs. As usual, Bob was talking sense, so Nigel and Terry decided it was a safe bet to play it Bob's way and part with the necessary cash. The total cost of Bob's proposed improvements weighed in at USD 37552 (Eur $6000). Calculating at a rate of Eur $2200/kilo, the first crop paid for itself and more than half the expenses of the proposed expansion and improvements. Cool!

Bob's plan was to: 1) Double the length of the existing two benches and line the walls of the other half of the storage area with white laminated wood; 2) Set up an automatic watering system with a large reservoir to reduce manual

labor; 3) Plant double the amount of clones per area to reduce time in vegetation by a week; 4) To achieve adequate air flowr install a new 5000 cu/hr fan for air extraction, and use their existing 3200 cu/hr fan for air intake; 5) Make use of current advancements in reflector technology to decrease the number of lights required—from 20 to 14-and consequently reduce the power usage and heat generation by the same ratio; 6) Bob also suggested ditching the pot idea in favor of cocopeat slabs. "Just supply the plants with a top-quality organic nutrient, and the garden will be state-of-the-art and organic."

The best way to explain the setup is to refer to Plate C. The room was set up pretty much as Bob had planned, Five Danish-made plastic 6 foot 6 inch x 3 foot 3 inch (2 Si 1 m) trays were loaded up with coco mats and placed on each 33 foot (10 m) long bench top. Each tray was installed with a 3-degree tilt to promote drainage. An elaborate system of drippers and drainage pipes was constructed and each bench was run as a separate entity with its own 400-liter reservoir and 6000 L/hr pump. Both pumps were timed to run x times a day for y minutes, and nutrient runoff was pumped out of the grow room and into the shower drain.

The fans were installed placing the 5000 cu/hr fan high at one end of the room and the 3200 cu/hr fan down low at the other. The 5000 removed air via the vent in the upper central part ol the room. The vent was box-shaped and permanently connected to the carbon filter. When the filter was not required, a cover on the under side of the box was removed, and air was drawn out through the exposed opening. The 3200 forced cool air through ductwork that ran along the lloor under each bench. This air entered the room in four places under each bench, equally spaced along their length. Four pedestal fans were used to mix the air and push it in the general direction of the outlet vent.

The room was lit using fourteen 600-watt lamps, each covering an area of 4 feet 8 inches x 3 feet 11 inches (1.43 x 1.2 m). This was achieved by using high-tech adjustable double-parabolic reflectors (Adjust-a-Wings). These flexible "wings" were highly reflective and could spread light evenly and broadly at a range of heights above the plants. They were rated to cover areas of 4 feet 11 inches x 4 feet I inch (1.5 x 1.25 m) and above with 600-watt lamps, so 4 feet 8 inches x 3 feet 11 inches (1.43 x 1,2 m) was within prescribed limits. Another lighting product was used in conjunction with the wings and referred to as a Super Spreader. These fit below the lamp and spread excess light and heat from that hot area across the light's entire footprint. They allow lamps to be close to plants to produce rapid growth but keep growth rate and plant size even.

When compared to the lirst, this crop almost seemed to grow itself! The irrigation system alone (reservoir size, how many days reserve, nutrient dosing, the coco/Danish tray/run to waste system) saved Nigel and Terry about two hours a day.

The ventilation design combined well with the simple, effective lighting strategy. Air was pumped in and pushed up from below, cooling plants and lights on its way up, The heated air would rise naturally, be trapped by the ceiling, sucked towards the vent/filter, and exhausted from the room. With a small amount of adjustment, the air temperature could be maintained at 80-82T (27°C to 28°C) even when the plants formed a dense mass across the whole room,

The wing reflectors could be adjusted to provide even lighting when they were close to the plants (growth and flowering phases) and when they were farther away (early vegetative and final maturation phases). When reflectors were hung low over the plants, the spreaders dealt with any hot spots and insured even lighting.

Nigel and Terry's second crop grew vigorously and evenly all the way through to maturity. They had a small problem early on with spider mites. Seems the clones they bought had a few mites onboard. The mites were dealt with organically and effectively. Bob had suggested the boys use

Growing Soilless

Growing Soilless

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