Starting Seeds Indoors

by Luke Zapadka

If space is available near a sunny window, start seeds four to eight weeks before our zone’s plant-out date (second/third week of May; end of May for seed vegetables). Starting too early usually results in spindly plants because of crowding and insufficient light. 

You can use almost any container – Styrofoam cups, tin cans, small milk cartons - with drainage holes made in the bottom. The plastic trays and pots sold here are more convenient.

Use a rich, well-drained soil, such as our Soil-less Potting Mix. Fill containers firmly with soil, but do not pack down. Leave about 3/4 inch from the soil surface to the rim of the container. Place seeds on the soil surface, then sift soil over the seeds to the depth indicated on the seed packet (a piece of window screen or a kitchen sifter can be used here).

If you use compartmentalized trays or individual peat pots, place two or three seeds in each pot. Do not cover too deeply, as this may reduce or prevent seed germination. As a general rule, cover no more than four times the diameter of the seed. 

Apply a very fine spray of water (a clean window sprayer works well), being careful not to wash the seeds, causing them to float to the soil surface. Cover the containers with plastic sheets or panes of glass and place in a cool room (60 to 65 degrees) away from direct sunlight until germination. Remove the plastic at least once a day to check moisture and give the seeds fresh air.

When seeds germinate, move them gradually (over two or three days) into brighter light. When the seedlings have developed the first true leaves (the leaves above the cotyledons or “seed leaves”), thin to one plant per container if using partitioned trays or peat pots. Use tweezers to pinch off unwanted seedlings rather than pulling them, to avoid disturbing the remaining seedlings. 

If seeds were planted in larger containers, transplant into individual peat pots or other small containers. An alternative is to thin the seedlings so they are spread about 1 1/2 to 2 inches apart and leave them in the larger containers.  

Water seedlings carefully. Small containers used for starting plants dry out quickly. On the other hand, soaking-wet soil inhibits seedling growth and may kill the plants.

About one week prior to planting-out time, gradually expose seedlings to longer periods outdoors unless temperatures are below 50 degrees. At the same time, reduce watering to a minimum as long as plants do not wilt. This will help the plants adjust to full exposure without undergoing undue shock at planting time.