“Stretching,” the term used to describe the rapid growth of cannabis stems, is a natural part of the vegetative stage and is influenced by plant genetics, among other variables. Unfortunately, stretching is a common perpetrator of low yields and lanky plants, resulting in teetering, physically unstable crops. Despite the threat it poses, stretching can be controlled by first examining the factors influencing its growth, then creating protocol to sidestep these issues. Controlling cannabis stretching requires an understanding of how plants interact with both their internal and external environments.
Every grower wants to see a cannabis garden packed with trophy colas of dank marijuana come harvest. Excessive plant stretching, whatever the cause, is guaranteed to rob you of this magnificent sight. Lanky cannabis plants with huge internodal spacing are to be avoided at all costs. Yields will be low and bud quality will likely be the same. Cannabis plants that grow too stretchy and reach for the sky are unlikely to deliver a hefty marijuana harvest. Tall, stretchy plants can even be too much of a handful for some master growers. We’ve got a few tips to suppress shoot stretching that will help you succeed in cropping a major stash.
Why Do Plants Stretch?
There are several reasons why plants stretch, one of which has to do with the strains themselves. Genetics plays a pivotal role in determining the eventual height of sativas, indicas and hybrids. While stretching isn’t harmful in and of itself, dramatic stem growth carries the potential of significantly lowering the crop’s final yield between 20-30% overall. When considering strains for your next home grow, research the common height of each variety you plan to grow in order to gauge whether or not the strain experiences a dramatic flowering stretch.
Choose Your Strains Wisely
The best way to avoid stretchy cannabis plants is to select a high-quality indica-dominant strain to cultivate. Indica strains are renowned for their squat and stocky appearance and come highly recommended for smaller grow spaces. Old school classics like Northern Lights and Afghan Kush have very short distances between nodes. At the opposite end of the cannabis spectrum are the sativa strains. Tall, slender and sparse branching sativa-dominant marijuana is less well-adapted to indoor cultivation. Even with early training and pruning, sativa sativa varieties will still stretch significantly during the bloom phase. Hybrids are often the best alternative. The very best will display a blend of the most desirable indica and sativa characteristics.
Lest we forget the “autos.” Most autoflowering cannabis develops just a single main cola with few side branches, excluding XL Super-Autos. Given that most next-gen hybrids usually peak at about 1m in height both indoors and out, autos are probably the simplest solution to plant stretching problems. It’s just not an issue with them. Autos are not for everyone, but for the beginner grower, they are the most forgiving cannabis plants to crop.
Light Spectrum For Cannabis
Get this right and you will reduce stretching in marijuana plants with minimal effort. Blue/white light is best for seedlings and vegetative growth, while the more orange/red spectrum is suited to flowering. To reduce stretching and to keep internodal spacing to a minimum, it’s best to use cool blue/white spectrum lighting that can be positioned close to the plant canopy. According to old-school cultivation methods, you could use MH or White CFL for vegetative growth, then switch to HPS for flowering. Nowadays, some growers tend to opt for Full Spectrum LED to support the complete lifecycle, but this is still a bit “futuristic” in terms of feasibility.
Take Care Of Air Circulation
Fans, fans and more fans! Use an intake fan to draw in fresh air. An extractor fan is a must to suck out the stale air. A pedestal fan (or at very least, a clip-on fan) is another necessity. Try to create a gentle breeze effect on your plants. Stems will be weak and later in bloom, branches may snap without wind to toughen them up from vegetative growth onward. Don’t forget to use ducting and to connect a carbon filter to the extractor fan to eliminate odour.
Manage Temperatures In Your Grow Room
Temperature is a key growth collaborator and inhibitor. Above 29°C spells trouble for cannabis. Too cold and plants will be stunted and dwarfed, too hot and plants will be spindly, burnt and even turn hermie. Heat stress in the upper canopy of the cannabis garden can do more than just burn foliage.
Worst of all, high heat makes shoots grow thinner and stretchy. This turns top colas into worthless, fluffy buds. Growers can avoid this by hanging lamps the correct distance from tops and by maintaining optimal temperatures from seed to harvest.
Topping is a form of manual intervention on cannabis to affect its yield, shape or size. In essence, topping is the process of cutting of a new, actively growing node from your plant in order to reduce its size and create a “v” shape that will then form two colas. Topping can be an effective measure for combating stretching, but it’s important not to top once the flowering stage begins.
Space Between The Plants
An overcrowded SOG won’t do you or the plants any favours. Don’t get greedy. If plants are spaced so close together that they are touching and leaves are shading most branches, the harvest will suffer. Plants will compete for light and race up vertically to survive. Long, thin stretchy colas don’t take home any trophies. They just don’t develop properly. Nobody wants a 50cm long stick of fluff or leafy popcorn buds for a stash.
The most effective method to maintain an even plant canopy that results in a harvest of big fat buds is the ScrOG. This technique is usually applied in combination with topping, LST or supercropping during vegetative growth. Deploying a screen and weaving shoots to fill out the grid is the best way to eliminate stretching as a problem.
In most cases, unexpected stretching from cannabis plants won’t destroy your yield entirely.For cultivators with sizeable grow rooms that can sustain tall plants, stretching may actually increase a strain’s total yield with more vertical surface area for colas to form.