Seedlings are programmed to survive, so if they are stretching, they are stressing. Learn how to fix this occurrence and prevent it from happening in the future.
Just like baby newborns, seedlings are very delicate things. They need as much tender loving care as possible. And in the case of our beloved cannabis plant, the best form of TLC is to provide it with ideal environmental conditions.
THE SEEDLING STAGE
Seeds are like little genetic time-capsule bombs. What this means is that they only have one job, and only get one chance to pull it off. They are pre-programmed to survive. A seed self-contains absolutely everything a future plant needs to get started. Once activated with moisture and darkness, it will trigger germination, and once that gets going, there is no turning back.
A seedling does not need any food for the first good few days of its life. From its genetics, it is already backpacking all the essential nutrients needed to embrace the miracle of life. Seedlings have a little reserve to help establish themselves in their growing environment.
In optimal conditions, the seed shell, or husk, will crack open and a taproot will pop out, immediately digging further down in search of a water lifeline. Soon, you will see a sprout rise from the under the soil, spread out its first baby leaves (cotyledons), and then you will start noticing the first set of true leaves. Leaves have an equally important job as the taproot, but they are in search of another food source – light. Quite literally, a plant uses light to digest what it brings up from the soil.
WHAT CAUSES ABNORMAL STRETCHING?
Abnormal stretching in the seedling phase is a sign of stress. By far, the most common situation that causes seedlings to stretch and topple over is light deprivation.
In the same way a taproot digs for water and nutrients, the top part of the plant will stretch vigorously if it is not receiving enough light. It is a survival mechanism. It will use up all its stored energy to rise above competing flora. In the case of indoor growing, there is no competition, but the seedling will perceive it this way. For instance, leaving the pot under a windowsill in the shade will likely trigger this behaviour.
This may seem a bit confusing for new indoor growers, as they may think they are providing more than enough light to their plants. But consider the following. Positioning a 200W metal halide bulb very far away from the pot will be less effective than a 20W CFL bulb a few inches away from the leaf surface.
Seedlings have very little leaves. The total surface area in which to absorb light is very small. So, in essence, that 200W bulb will be radiating over a very large area, but the seedling can only use a minute fraction of it. The CFL position right over the plant will be able to give most of its 20W directly.
HOW TO FIX THIS?
Luckily, there is no major harm done if the situation is dealt with quickly. Some people opt to stick a support stake (a straw, pencil, chopstick) until the plant grows out enough to support itself. This works, but is not the optimal solution.
A better technique is to gently scoop out the plant from the medium, being very careful not to harm the little roots. You then proceed to dig a much bigger hole and replant the seedling in deeper, making sure to bury most of the overgrown stem. With time, the buried stem will start shooting roots.
Give your babies direct sunlight, not shade. If growing indoors, lower your lights if possible. Just be sure that potential heat stress is not a problem. HID lights may be too heat-strong for seedlings if you set them too close. Lower-powered LED or CFL may be a better option at this stage.
You will soon notice how the first set of leaves start growing. The young plant is now happy and able to photosynthesise. It now triggered leaf grow and not stem growth. All the energy is directed to produce chlorophyll, which in turn promotes even more photosynthesis.
The young plant now has all the right ingredients to achieve its full potential.