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How to Take Care of Seedlings

Updated: Apr 11, 2023

In our last blog, we talked about starting seeds. If you missed it, you can read it here.

Once your seeds have germinated and you can now see a small stem with some leaves, they are called seedlings. Once they have a root mass they are considered a plug.


If you started your seed in a seedling tray, you will need to transplant it to a bigger container once the roots have reached the bottom of the cell tray.

Transplanting it into a bigger container will allow the roots to have more space to establish a healthy plant.


The seedlings will now grow better at a lower temperature (about 10 degrees lower). If you are using a fluorescent bulb, move it up several inches gradually for a couple of days. After this your seedlings will love to grow in the sunlight by the window.


Do not fertilize your seedling until it has 4 to 6 true leaves. The seed starting potting mix that was used to get the seeds to germinate (combination of peat moss, vermiculite, and perlite), does not have any of the nutrients in it that the plant needs to grow. Once your seedling has quite a few leaves you can start to fertilize very slowly.

The ideal fertilizer for your seedling is a fertilizer that produces root growth such as 10-52-10. You may have heard someone say that you should use an all around fertilizer like 20-20-20 but this will cause your plant to focus on growing leaves, it will become lanky and will put energy onto the top instead of establishing strong roots. Since your seedlings are still tiny plants be very careful that you do not fertilize too much, it is always better to under-fertilizer than to over-fertilize! Use 1/2 or a 1/4 of the fertilizer that the instructions say (if the fertilizer says to use 1 tbsp. per 1gallon, use 1/2 or 1/4 tbsp. per 1gallon water). Apply the fertilizer onto moist soil instead of dry, this reduces the chance of your plant getting fertilizer burn. At first, fertilize gently once a week, if you miss a week that is totally okay, it is better than fertilizing too much. As your seedling grows it will be able to handle more fertilizer.


Overwatering can be disastrous, even fatal. It can cause the stems to rot and the roots may become water logged, cutting off oxygen to roots and possibly creating mold on the soil. Underwatering can also be disastrous, if your seeds get too dry they won't germinate, seedlings that are too dry may wilt and won't be able to recover because they don't have an established root system. Consistent watering is the key to establishing strong plants quickly.

The recommended method of watering containers or trays indoors is to water from underneath. You can do this by setting the container into a shallow saucer with water. Your plants suck up the water through the drainage holes at the bottom, let them sit in the water for about 10 minutes before removing.

The frequency of you watering depends on a few factors, the general rule of thumb is that you water your seeds and seedlings once a day. The type of container and soil, light conditions, growing media and surrounding environment might make a difference with this. A simple test that you can complete to check if your plants need water is by grabbing the top parts of the soil and seeing if it is moist or not, if it is you can hold off on watering for a little bit longer.

If you read our blog about starting seeds you may remember what we said about chlorinated water. We said that you should try to avoid using chlorinated water or water that is high in salts and bicarbonates. If this is the only water source that is available, let it sit for 24 or 48 hours before using.


Just like we need oxygen to survive, plants need sufficient air circulation to thrive. You will notice all greenhouses have large fans in their building for this reason. Without air circulation your plants will be more susceptible to mold and root rot, and diseases. Plants need the air circulation to grow and photosynthesize properly, with proper air movement the stems of the plants will toughen up and be less lanky. To provide sufficient air flow, set up a fan adjacent to the plants and let it (very lightly) blow over the plants.

Once the temperature stays above 10 degrees Celsius outside during the day, we can start to acclimatize our seedlings to the outdoors. If you would like to know how to do this so that your seedling does not get shocked, but rather toughens up in one week, read our blog where we talk about acclimatizing seedlings to the outdoors (view here).

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