Starting Seedlings: Environmental Conditions and Ongoing Care

Now that you've sown your seeds, it's important to know a few other miscellaneous things in order to take care of the seedlings.

Watering:

Young seedlings need to be watered frequently. The smaller the pot size and warmer the temperature, the more often you'll need to water. I grow my seedlings in my basement where it is fairly cool (about 60-62 ºF), but I still have to water daily. One of the biggest mistakes is overwatering your seedlings. If your seedlings sit in soggy soil for a length of time, the roots will become oxygen starved and start to rot. These damp conditions can also promote mold growth and damping off (collapse of young stems at soil level). To avoid these problems, let the soil dry down between waterings. Water soluble fertilizers can be applied every time you water

Fertilizing:

Small amounts of soluble fertilizer can be mixed into your water and applied every time you water your seedlings (follow the package instructions). Pelleted fertilizers can be mixed into the soil or spread on top of the soil. If you want to grow organic crops, you will need to use organic fertilizer rather than synthetic fertilizer.

Air Circulation:

Good air circulation helps seedlings in two ways: 1) the mechanical movement caused by wind will promote strong and thick growth. Stocky seedlings are healthier and easier to transplant than spindly ones. 2) Air circulation will help prevent damping off of seedlings.

Temperature:

If you are starting seedling in your house, most seedlings will grow just fine at room temperature (~72 ºF). However, if you keep your house cooler than this, or you are growing in a basement (like me) or some other cool location, additional heat may be beneficial (but not necessary). Supplemental heat will hasten the development of many crops up to a certain point (but if too hot, the seedlings will dry too quickly). Extra heat is especially useful during germination for some of the warm-weather crops like tomato, pepper, and eggplant and can be supplied by electric seedling heat mats. If you grow in a cooler location and don't have a heat mat (they're expensive), your seedlings will just take a little longer to develop.

Electric heat mats help warm the soil and speed up germination.