Congratulations on committing to cannabis cultivation. Now you need to settle upon the right number of cannabis plants to grow. We’ve got practical advice you can use whether you plan on growing just one plant, or as many as you possibly can fit in the grow space.
HOW MANY PLANTS CAN I GROW PER SQUARE METER?
Before you get your grow on, you need to have a plan and a timetable. First, you need to establish the size of the available grow space. Grow tents come with exact dimensions on the box. However, if you are building your own grow box, or converting a whole room into a grow-op, you need to first take measurements. Next, you must decide how much light you can put down while still maintaining optimal environmental conditions. We will breakdown the key factors to consider when choosing grow lights a little later.
Perhaps the most important question the grower needs to ask him/herself is; how much time can I commit to cannabis cultivation? Work, family, and social commitments can make growing a difficult balancing act. A large sativa plantation will be far more time-consuming to maintain than a couple of autoflowering plants in a wardrobe.
The genetics you choose and your preferred grow style will ultimately determine how long it takes to bring your crop to harvest. Precisely how many plants to grow is a personal choice. But the following will help you discover your indoor marijuana magic number.
HOW MUCH LIGHT DOES MY GROW-OP NEED?
It’s not as simple as purchasing as many of the most powerful grow lamps you can get your hands on. Every grow space is different. But two factors always need to be tightly controlled and constantly monitored. Temperature and relative humidity (RH) are the key environmental conditions the indoor grower regulates. You need the right tools. Invest in intake fans, extractor fans, and if available, air-con or heating.
HID – HIGH INTENSITY DISCHARGE
HID lamps are a great source of illumination for the grow room and still favoured by most professionals. Unfortunately, MH and HPS lamps run hot and will significantly increase your power bills, too. One 400-600W bulb per m² is a good rule of thumb. Although, you may need to scale down to a 250W bulb. Consider improving side reflection with Mylar sheeting if you can’t keep temperature and RH dialled-in. Using high-powered old-school lighting necessitates the use of more powerful fans and possibly air-con, or else the grow-op may run too hot.
LED – LIGHT EMITTING DIODE
Modern LED grow lights run much cooler and more efficiently than HID. The main drawback with next-gen LED is the substantial investment required for a decent high-quality kit. Over the long-term, you can recoup with the savings you make on the power bill. Choose your LED kit carefully as not all LED’s are created equal. At present, 3W diodes and COB appear to be the most promising technologies. Less heat and more usable light per watt can also save you some money when it comes to selecting fans to regulate airflow.
CFL – COMPACT FLUORESCENT LIGHT
CFL can only take you so far. Sure, they are economic and efficient, but only to a point. In this writer’s opinion, cool white CFL is fine for vegetative growth and rooting clones, but nothing more. Using CFL’s alone for the bloom phase is not recommended. However, adding CFL as a supplement to HPS during bloom can be a winning combination.
HIGH VOLUME CULTIVATION: (SOG) SEA OF GREEN
The sea of green method (as the name implies) is all about packing all of the available floor space in the grow-op with plants. Typically, photoperiod clones or autoflowering strains are used to achieve a consistent, controlled outcome. This technique is fast and very high-yielding. Rooted cuttings get from 1-2 weeks of vegetative growth before the switch to standard 12/12 flowering of 8-10 weeks. On the other hand, autos can be kept on a consistent 18/6, 20/4, or 24/0 schedule and be ready for harvest in 8-10 weeks from seed. There is no time for pruning or training, nor is it needed.
As plants are not given time to branch out, many short plants with chunky main colas are the objective. Approximately 4-16 plants per m² can be cultivated under 400W HPS, sown in 5-12l containers. Watering by hand can be very time-consuming with such large numbers. Many growers prefer hydroponics kits with automated feeding systems when cultivating many plants. A well-run SOG grow-op can deliver 4-6 500g/m² harvests per year.
PRUNING AND TRAINING FOR MAX YIELD
If you want to keep the number of cannabis plants to a minimum and still get maximum yield from your grow space, then you need to apply yield-boosting techniques. You have two choices; pruning and training. Of course, you can do both. In fact, we highly recommend combining methods for best results.
TOPPING & FIMMING
The most common pruning-for-yield methods are topping and fimming. By pruning the main stem and breaking the apical dominance, bigger yields can be achieved. This is done either with a clean cut by “topping,” or a pinch leaving 25% of the main tip via the “fimming” method. Plants will bush out and develop multiple main colas instead of just one. Both methods can be applied repeatedly depending on how much lateral space you wish to fill.
Remember, each time you prune marijuana, you must allow recovery time. The cost of these pruning-for-yield methods is indeed time itself. Expect an extended vegetative growth cycle. 6-8 weeks will be required for two well-pruned bushes to fill out 1m².
LST – LOW STRESS TRAINING
LST or low stress training is a beginner-friendly training technique that, like the two aforementioned pruning methods, works well with a ScrOG or screen of green technique. By bending or tying stems during vegetative growth, the grower can manipulate the plant to grow more like a bush. 2-4 plants can effectively fill 1m². Recovery time is just a few days and this method even works with autoflowering strains.
SCROG – SCREEN OF GREEN
Experienced growers that have mastered one or more of the above techniques can further increase the yield of any grow space by combining pruning and training with a ScrOG. Weaving shoots through a screen from vegetative growth to week 3 of bloom is the professional way to utilise grow space where it counts most. Keeping exclusively main colas directly under the sweet-spot of your light is what ScrOG is all about.
All growth below the screen is pruned away to focus plant energy on bud production. 8 weeks or more of vegetative growth and daily maintenance are required, but even an individual plant can produce a scale-tipping harvest to match a SOG in an organised, cola-packed ScrOG.