Cannabis plants are surprisingly versatile little dudes that adapt to the contours of their surroundings, which is great news for growers as it opens up multiple possibilities for controlling the size of their crop. For instance, those operating in a particularly small grow space can prompt their plants to bulk up their colas and increase their production of THC. In this article, we’re going to look at how to get as many cannabis plants as possible into a miniature grow room, grow tent or other small spaces.
It All Starts With Genetics
Regardless of your grow setup, achieving your objectives depends on choosing the right genetics. In this case, that means working with small plants.
As a general rule, indica strains tend to remain stockier and more compact than sativa cultivars, so opting for the former if you have limited space makes sense. Autoflowering cannabis plants are often even smaller and are a great option for growers who want to cram as many plants into their workspace as possible.
While loads of strains work well in a tiny space, Green Crack Auto is a particularly good option as it grows in a compact pattern with one fat central cola. Therefore, growers can prune most side branches to ensure the plant occupies the smallest amount of space possible.
For those who prefer working with photoperiod cannabis strains, Bubba Kush may be the way to go. This stocky little Indica is nice and small in stature but absolutely packed with bud.
Lighting
Once you’ve found yourself a compact strain to work with, you’ll need to do everything you can to prevent it from stretching during vegetative growth. The best way to achieve this is to keep your grow lights as close as possible to your cannabis plants.
While that may sound simple enough, bear in mind that marijuana plants are sensitive to heat stress, so placing your lights too close can severely stunt plant growth. To avoid this, it’s worth investing in LED lights, as these produce far less heat than HPS or CFL lamps.
Not only do LED grow lights minimise the risk of heat stress, but they also help prevent the temperature in your grow space from soaring, thus reducing the need for climate-control equipment and leaving more room for plants.
It’s also worth installing lights that emit wavelengths within the blue region of the light spectrum, as this will help your plants to remain small. Red light, on the other hand, encourages plants to stretch.
Getting To The Root
The size of a plant is directly linked to the size of its root system. To keep your weed small, it’s essential to control the growth of the roots.
The simplest way to do this is to use small pots. However, limiting the amount of space available for the roots can be risky, as plants can become root-bound when grown in small containers. Don’t hesitate to transfer your plant to a bigger pot if this occurs.
Smaller containers also mean less soil, so plants grown in ungenerous pots will likely need more regular watering and feeding than those grown in larger receptacles. Some growers, therefore, choose to use super soils, which are better at retaining moisture and nutes than regular soil.
Choose The Right Growing Techniques
There are a number of cannabis cultivation techniques that can help growers get the maximum number of plants into the smallest amount of space. Generally, the practice of growing large numbers of small plants is referred to as the ‘sea of green’ method.
Some growers choose this approach as it allows them to harvest their bud much earlier than they would when growing larger plants. Rather than waiting for a few plants to produce enormous colas, it’s possible to end up with the same amount of weed from loads of less-developed plants.
The key to this technique is knowing when to alter the light cycle and trigger the flowering stage. Generally, the photoperiod should be switched to 12/12 when plants reach half their desired height, as they will usually double in size during bloom. The earlier you initiate flowering, the smaller your plants will be, although pulling the trigger too early could result in poor yields.
Another option for growing weed in small spaces is the so-called screen of green (SCrOG) method. Scrogging involves weaving a plant’s branches through a wire mesh to expose more nodes to the light, resulting in multiple colas instead of a single central bud site.
Likewise, low-stress training (LST) can be employed to gently bend a plant so that the light reaches more nodes. High-stress training (HST) techniques such as topping, fimming or super cropping can all help to keep plants short yet stacked with bud.
Interestingly, a recent study found that a technique called re-tipping can help cannabis growers cultivate nine times as many plants in the same amount of floor space as more conventional methods[i]. At this stage, re-tipping is something that is more likely to be trialled by cannabis industry professionals than home growers, as the method relies on creating plants from tissue culture under lab conditions.
Essentially, the technique involves taking repeated cuttings from micro-propagated plants, which are more robust and less prone to disease than traditional clones created from a mother plant.
Don’t Forget The Basics
While re-tipping may be a little advanced for most people, sticking to the basics of cannabis cultivation can help ensure success when trying to produce large numbers of small plants. Air circulation, for instance, is vital in any grow space and ensures that all plants have the carbon dioxide they need for photosynthesis.
Keeping lots of plants in a small space also increases the chances of mould or fungal infections, so it’s essential to keep humidity and temperature under control at all times. The more cluttered your grow space, the more likely it is that fallen leaves or other plant material will gather on the floor, creating a welcoming habitat for all sorts of nasty pathogens.
For this reason, it’s highly advisable to clean your growing area regularly, even if this means moving plants around so you can access and remove hidden dirt.
[1] Lauren E. Kurtz et al, Ex Vitro Rooting of Cannabis sativa Microcuttings and Their Performance Compared to Retip and Stem Cuttings, HortScience (2022) - https://journals.ashs.org/hortsci/view/journals/hortsci/57/12/article-p1576.xml