Seed Starting Basics
Earlier is Not Better
Many new gardeners, especially those in areas with short growing seasons, assume that planting seeds earlier than recommended will produce large healthy plants for transplanting to the garden. Although it’s a logical conclusion, unless you have a home greenhouse and good supplemental lighting, starting them too early may do more harm than good.
Two basic problems arise from starting seeds too early, says the University of Arizona Extension.
Two basic problems arise from starting seeds too early, says the University of Arizona Extension.
- Unless you live in a southern climate, the strength of the sun's rays simply is not strong enough to support healthy plant growth in late winter. Seedlings emerge and stretch to reach more light creating tall, spindly plants.
- Seedlings that are started too early become weak and leggy due to both inadequate light and improper temperatures (either too warm or too cold). Once transplanted to the garden, these plants rarely produce well.
Determining Planting Dates
- Check the seed packet or refer to a good gardening book to determine the appropriate time to start your seeds. While some seeds should be planted 10 weeks or more before the transplant date, many require 4 to 8 weeks.
- Determine the date of the last expected frost in your area and count back the appropriate number of weeks to determine planting time. Follow these recommendations as closely as possible for best results. With a few exceptions, such as planting tomatoes and peppers, these dates will give you the best results. (Tomatoes and peppers are typically labeled for starting 4 to 6 weeks before planting time, but this does not give them enough time to reach a reasonable size here in Maine. They typically require at least 8 to 10 weeks to reach the desired size when started in the home.)
Seed Starting Mixes (Soil)
Use a soiless mixture for seed starting. You can buy seed starter for a few dollars in your local hardware store or home improvement center. Reused potting soil or garden loam is too heavy for seed starting and may contain contaminants that will damage your seedlings. Take the extra time and effort to buy new seed starter to get your plants off to the best start or make your own seed-starting mixture.
Planting the Seeds
- Fill trays ¾ full with seed starter. You can purchase seed starting trays with plastic domes for seed starting, but this is not necessary. You can use peat pots, peat pellets, recycled plastic containers, disposable cups or even old egg cartons to start seeds. I prefer peat pots or pellets because they are easy to use and can be planted in the soil without disturbing the roots of your plants by tearing off the outer cover or removing the bottom, but what you use it up to you.
- Mist the seed starter with a fine spray of water to prevent dust. Plant seeds to their recommended depth. Press fine seeds, such as begonias and petunias, into the surface of the soil, but do not cover. Larger seeds typically require a depth of 1/8 to ¼ inch. Cover the seeds lightly and firm down with your hands to secure the seeds.
- Water thoroughly until water runs freely through the bottom of the container. Cover the trays or pots with plastic food wrap to hold in moisture.
Germinating the Seeds
Place the seeds in a warm location, but avoid direct sunlight. Direct sunlight may overheat the soil and prevent germination. An area that receives gentle bottom heat, such as the top of a water heater or a germination pad is ideal.
Seedling Care
Remove the plastic once seedlings emerge and place them in a sunny location that receives bright, indirect light. Gradually move seedlings to direct sunlight by moving them closer to the window each day.
Keep the soil evenly moist. Seedlings may need to be watered several times a day.
Keep the soil evenly moist. Seedlings may need to be watered several times a day.
Fertilizing Seedlings
Begin fertilizing with water-soluble fertilizer mixed to ¼ strength when seedlings are 2 to 3 weeks old. Using a weakened solution prevents damage to roots and promotes healthy vigorous growth. Gradually increase the strength of the fertilizer solution as plants mature.
Transplanting Your Seedlings
Transplant seedlings to the garden once the danger of frost has passed in your area. Place the plants in prepared soil so that they rest at their original planting depth. Firm the soil around the roots with your hands and press down to secure the plant. Water thoroughly to moisten the soil to the root level. Keep soil moist until new growth appears and then resume the recommended watering schedule for your plants.