Seedling Stage

what is the seedling stage?

The seedling stage of the cannabis growth cycle requires a lot of care and attention. Seedlings at this stage are more prone to mould and disease, so it is vital you keep monitoring your plants and keep excess moisture to a minimum. The plant does not need too much water or nutrients at this stage either.

The two round leaves that will first sprout out, also known as cotyledons, were already formed inside the seed. The next two leaves that will form will start to be more recognisable as a cannabis plant. Your seedling will slowly develop more leaves and is considered a seedling until it starts developing new sets of leaves, with 5 to 7 leaflets on each leaf. Healthy seedlings are a bright green colour. The seedling stage will last for around 2 to 3 weeks and the plants will be ready to transport into a larger container when the roots start appearing at the bottom of the small seedling pot. 

plant just growing
cannabis first leaves

how to care for your cannabis seedling

Do not over water

A common mistake during this stage is to over water your cannabis plant. This will make the leaves go droopy. This is due to your plant not receiving enough oxygen, rather than too much water. Reasons for over-watering include:

Poor Drainage

If your marijuana plant is in a pot that cannot drain, then the roots will get flooded with water and the plant will be starved of oxygen. To stop this, use both a pot and a growing medium that drains well. A good quality potting mix with perlite is a great choice.

Using a pot that is too big

As a seedling, the roots will be very small and so by using a pot that is too big, you may be using too much water than is needed. Putting your seedling into a smaller pot can actually help it grow faster.

Watering too much

By giving your seedlings too much water, there are no spaces of air for the plant to take in oxygen, meaning the plant could end up drowning. Mixing in perlite can be helpful in increasing oxygen, as well as using a container that allows air to come in from the sides of the pot. When watering, make sure that the inch at the top of the growing medium or soil is dry, before watering again.

Do not under-water

Under watering your cannabis plant will also result in droopy leaves, which may wither or not grow well. While the symptoms may look similar to over-watering, in this case the soil around the seedling will look very dry. The aim is to find a balance between the two. The soil should be always moist but not so much so that its sitting a in layer of water.

baby plants in tray

Give your seedlings the right amount of light

The light intensity should be kept low during the seedling stage, as the leaves will have not fully developed. Instead of using grow lights just yet, try using an LED propagation light or a low watt fluorescent light (15-25 watt). Try putting the lights around 2 to 4 inches from the leaves (experiment to see which works best with the power of your light). Once the shell has emerged through the soil, start switching on your lights. You know if your seedling is not getting enough light as the stem will stretch very tall. If this is the case, then either bring your lights closer to the leaves or turn up the brightness of the light.

Monitor the temperature of cannabis seedlings

It is important to keep an eye on the temperature of your marijuana seedlings. Seedlings like warmth and around 22 to 26 degrees Celsius is the optimal temperature. Seedlings are more sensitive and therefore its best to keep a consistent temperature during this stage, which can be done using lighting. The Relative humidity (RH) should be at around 60 to 75% and you can maintain this by using a humidity dome.

Do not give too many nutrients

If your leaves are discoloured, yellow or spotty, this could be a problem with the nutrient level. Heathy leaves will be a nice bright green colour and if this changes, then find out the problem and act quickly. If you are giving too many nutrients, the tips of the leaves will start to discolour. To stop this, avoid using a nutrient rich soil, or a slow releasing nutrient soil as it will be too many nutrients for the seedling to handle. Yellow leaves may mean you are giving the wrong nutrients to your plant.

Protect your plants

Seedlings should ideally be covered with something to protect them from insects and other pests. Covering them with a see-through plastic dome can work well. Keeping them indoors, warm, moist and with plenty of light will help them grow to their full potential.