Seeds planted in damp seed starting material shouldn’t need more water until they show green and start growing. If you’ve covered your seed trays with a clear plastic cover, or plastic wrap, they should stay plenty moist, but check your seed trays weekly for moisture after a couple of weeks. A spritz of water from a spray bottle should be enough.
Most seeds need to be in a room with temperatures between 65-80 degrees. The seed packet should tell you what temperature to maintain, but if it doesn’t you can look up online the variety you are growing. You can use a heat mat under the seed trays to help keep the soil at the desired temperature, or additional warmth can be supplied by lights close to the soil. Once the seedlings start to grow, they will need light.
Moving to Light
When your seeds have germinated and are showing green, it’s time to take the plastic covers off and get the babies under lights. It’s possible to grow seedlings in a bright sunny south facing window, but make sure they don’t get too hot.
First Green Leaves
The first green leaves to show on your seedlings are called cotyledons (temporary leaves) and don’t conduct photosynthesis. Sometimes these will even have the seed still attached like the picture above. True leaves will develop and look different.. Once the true leaves appear, the cotyledons will wither and fall off. After a few more leaves grow, you can transplant the seedling into a bigger pot or into the garden.
While your seedlings are inside, watering is critical. As they grow and form a canopy over the flats, you need to make sure they are getting water at the roots, so you’ll need to put water directly on the soil and not on top of the leaves. Overhead watering can lead to disease and do as much damage as too much or too little water.