Growing weed is not only interesting but good fun too. Not everything is as rosy, though, for it’s also a bumpy ride full of twists and turns. A good start is always key for a good finish, so having a solid understanding of the ins and outs of marijuana seedlings can be the difference between success and frustration. By controlling their size, boosting the growth of their roots and providing them with the right kind of nutrients, we’ll lay the foundations for stronger plants and better yields later on.
The first stage is as quick as it is beautiful: right after germination, the embryo emerges through the seed coat and turns into a tiny root when sowed. As it receives nourishment and moisture, the little seedlings start to appear. In botany, this stage is known as the stage of development, and it extends from the germination and subsequent emergence of the cotyledon (two round-shaped primary leaves) to the unfurling of the first true leaves (a set of jagged leaflets). These plants are still rather fragile and spindly, and many inexperienced growers fail to properly analyze the needs of the newborn seedlings, sometimes even causing them to die.
Searching for light: what to bear in mind
Sometimes, our little kids grow more than it's good for them. An excessive vertical growth gives way to weak plants with low yielding capacities. This can be down to either environmental or genetic factors, as it's the case of sativa plants:
- Shoots also have a strong survival instinct. In the same way as roots reach out for nutrients, shoots grow towards the light. This phenomenon is called positive phototropism, and auxins play a major part in it. So, if your plant shows an exaggerate vertical growth, it may be suffering from stress due to an absence of a strong light source.
- Outdoors, plants move according to the sun, their main source of heat and light, which explains their relentless need to fight for light and avoid staying in the shadows. To prevent this from happening indoors, we recommend using grow lights properly, moving them in such a way that plants receive enough light to grow adequately.
- A less potent but better-located lamp is far better than a powerful yet poorly placed one. For best results, use reflectors or grow tents that allow for a more even distribution of light.
- Temperature has also an effect on our plant's growth: if over 80°F, our kids will start to grow upwards. Be careful with environmental stress too for stressful situations such as plant transplants can cause them to become too flimsy and leggy. Seedlings react to stress or uneasiness (when they're not happy with the substrate they're growing in or aren't receiving the right amount of nutrients) by stretching out. Be particularly vigilant in this regard.
- Instead, if your newborn seedlings seem unable to grow upwards because they're either too weak or too fragile, you can use a vertical support to help them out. A slight breeze will also make shoots stronger and more resistant because plants are forced to focus their energies on the reinforcement rather than on the stretching. This means that plants will continue growing vigorously yet not so much upwards.
Watch out for stalking fungi
Some of the most common infestations affecting early plants are the ones caused by parasitic fungi generally related to Rhizoctonia and Pythium. These produce a very common plant disease known as 'Damping off' that causes tiny plants to wither and die.
The presence of these harmful organisms, who love wet and warm environments, prevents nutrients from moving around and so roots from absorbing them. The best way to fight them is prevention. Keep a watchful eye on the moisture levels and avoid overwatering your plants. If you see the surface of the substrate is still damp, don't add any water. Wait until it's dry.
Purple doesn't always mean healthy
The color of your plants can say a lot about their health. Sometimes stems turn purple, and this might be down to multiple factors. It could be a matter of genetics. Or it could be the temperature. Just make sure the air temperature doesn't go lower than 68°F. Otherwise, you risk getting purple stems.
If it's limited to the stems, no need to worry. However, if it also affects the leaves, it may be a telltale sign of phosphorus deficiency. Consequently, plants will produce smaller buds, so finding a solution is paramount. All you have to do is use phosphate fertilizers.
If the coloring fails to disappear, and more and more leaves with fragile stems keep emerging, the reason could be excess nitrogen, which will lead to lower yields. The best solution is to thoroughly cleanse the root zone by overwatering your plants.
Fertilization? Yes, but with caution
First things first: root growth stimulation is a very important process. Poorly developed roots will be unable to absorb the necessary amount of nutrients to thrive and produce generous harvests. To prevent this from happening, during the 1st and 2nd weeks, you'll have to pour some root booster into the irrigation water.
'Till the start of the vegging phase, your seedlings will grow perfectly well without the help of any nutrients. The ones in the substrate will be enough. If you've picked a nutrient-rich substrate, like manure or earthworm humus, you can forget about fertilizing at least until the 4th week. If you haven't, start using nitrogen, phosphorus, and potassium-rich fertilizers as soon as the 3rd week kicks in and until the beginning of the pre-blooming stage.
Let them grow strong
Plants should be well rooted. That's the most important thing. If you succeed, you'll have come a long way. During the first two weeks, you'll have to make sure roots are developed enough to absorb all the nutrients cannabis plants need. Now that plants are so young, the use of chemicals is not recommended for any little mistake could be fatal. That's why ecological systems are preferred. Apart from less aggressive, they're far more sustainable.
Auxins are powerful growth hormones produced by plants that greatly benefit both stems and roots. For that very reason, boosting its production could help roots grow much more quickly. Some cereal crops such as wheat or bird seed, as well as some legumes, say lentils or chickpeas, could be of great use in this regard. All you have to do is pre-soak them in water for 8 hours to obtain an excellent root boosting solution.
At first, plants are better off in small pots. The big ones inevitably have higher amounts of humidity in the soil, and our seedlings are too small to take up that much water, so they may end up dying. But a moment will come in which the seedlings won't be small anymore and will need a transfer. When your seedling has developed 4 sets of leaves or roots start to entangle and get out of the pot, it'll be the time to transplant it so that it can continue growing more, faster, and stronger.
And remember that, unlike humans, cannabis seedlings growing too much too early is a bad sign. Although it may be an inherent feature of the strain chosen, the stem growing in excess may be a telltale sign that something is wrong: this kind of growth pattern gives way to weak and fragile plants unable to support the weight of their branches or leaves.