Once your seeds have germinated, how do you give your young plants the best possible start? Read the Science of Seed Starting.
- Keep a careful watch. We can help seeds germinate in many ways, depending on their requirements. Whichever method you use, when you see unsown seeds sprout with a root or seed leaves, be ready to sow them quickly in a tray. If you are growing your seedlings inside, make sure that they have enough light for strong, healthy growth.
- Give roots room to grow. Some seedlings, like those of butterfly milkweed (Asclepias tuberosa), need to be planted in deep cells that allow their taproots to extend downward. I usually sow taprooted seedlings in pots or trays that are at least 5 inches deep (photo).
- Harden off with care. Indoor- or greenhouse-grown plants can scorch from sun and wind if they are moved outside too quickly. An easy way to harden them off is to place them in a shady spot, then gradually increase the amount of light and exposure they get over a week before planting.
- Fertilize to promote growth. Many seed germination mixes have a light amount of fertilizer in them to help get plants started. But because frequent watering leaches the nutrients, you will soon need to provide your young plants with more nutrients. I like to start new seedlings off with half-strength fertilizer for the first week or two to avoid salt burn.
To learn more. Many seed companies have great information about what seeds require to start growing. In addition, I recommend a wonderful free online reference from the USDA that provides germination requirements for over 2500 species: Seed Germination Theory and Practice by Norman C. Deno.
Jared Barnes, Ph.D., is an assistant professor of horticulture at Stephen F. Austin State University in Nacogdoches, Texas.