Would you like to get a jump-start on your spring garden? Raising your own seedlings can be a fun and rewarding hobby. Besides the personal satisfaction, raising your own flowers and vegetables from seed will give you a head start on the growing season, save you money from buying plants plus give you an unparalleled selection in varieties.
Like so many gardening practices, starting seeds indoors is not difficult but does require patience and attention. The following tips, while not exhaustive, will help you through most of the seed-starting issues you may encounter.
- Seed selection — Carefully read seed packets and garden catalogs for germination requirements. Order seeds in early winter to make sure you receive them on time. Check suggested starting dates on the seed packets and mark your calendar.
- Containers — Always start with clean containers with drainage holes. A variety of containers can be used, from recycled yogurt cups to biodegradable peat pots. Be sure to sterilize used containers with a solution of one part chlorine bleach to 10 parts water.
- Soil mix —Use a soil-free mix for your seed-starting. These mixes are sterile, lightweight and the right texture for fine seeds. Several hours before planting, moisten the mix with room-temperature water. Soil-free mixes do not contain nutrients for plant growth so once seedlings have developed their first set of true leaves, begin fertilizing with 1/4-strength water-soluble fertilizer, such as 15-30-15 or 20-20-20.
- Sowing seeds — As a rule of thumb, sow seeds to a depth of 2 to 3 times their thickness. Tiny seeds and those needing light to germinate should be surface-sown and gently pressed into the soil mix. Seeds may be sown directly into individual containers or sown in quantity in one container and then transplanted. Gently mist containers after planting. Place containers in a clear plastic bag.
- Light and temperature — Place seeds in a warm location out of direct sunlight for germination. Most seeds require a temperature of 65 degrees to 75 degrees. Watch carefully, and once germination has started, remove the plastic cover. Even though seedlings can be grown on a sunny windowsill, fluorescent lighting will give a greater chance of success. Keep lights 2 to 3 inches above plants for 14 to 16 hours a day.
- Thinning and transplanting — Once seedlings have developed at least one set of true leaves, it is time to transplant them or thin them out. If the seedling is in an individual container, thin to one seedling per pot. To transplant seedlings into individual containers, gently tease them apart with a small utensil such as a pencil. Handle them carefully by their leaves instead of their delicate stems. Poke a hole in the soil with the pencil and plant the seedlings at the same depth they had been growing. Gently mist to settle in.
- Hardening off —The last step in seed-starting is hardening off the seedlings. This prepares the seedlings for the outdoors. About two weeks before outdoor planting, gradually acclimatize the seedlings by placing them outdoors for short periods of time. Start with a shady spot for an hour or two, then gradually increase the length of stay and sun exposure. Do not put seedlings out on windy days or when the temperature is below 45 degrees. Seedlings should have spent at least one overnight outdoors before being planted in the garden.
Two suggestions for seed starting:
1. Don't start too many.
2. Don't start too soon.
You may find your enthusiasm for gardening has resulted in a house full of struggling, elderly seedlings with no place to go. Following these tips should give you some healthy seedlings and a head start on your spring garden.
Barbara Michael has been a Master Gardener since 1993, and serves as the Master Gardeners’ liaison to the Community Garden Coalition, in addition to serving on its board. She enjoys container gardening and houseplants. She can be reached at firstname.lastname@example.org.