Some varieties are best started indoors because you have more control over the growing conditions. If you are a gardener in an area with a short growing season, starting seeds indoors extends your gardening season, allowing you to grow varieties that require longer growing times.
Containers and trays: Almost any container can be used to start seeds including milk or egg cartons, yogurt cups, or plastic berry trays. When reusing any container, it should be cleaned and sanitized and have holes that allow excess water to drain. For easy transplanting, try sowing seed in a paperboard or pulp pot— a biodegradable pot that can be planted directly into the garden. This saves you time and minimizes root damage to your seedling.
Media: A high-quality seed-starting mix, a type of growing media, is loose and lightweight yet holds moisture and is free from sticks and bark. Avoid potting soil mixes or soil from your garden that may have bugs, weeds, or diseases that can affect germination. Thoroughly moisten media before filling your container.
Moisture: Covering your containers with a clear lid or clear plastic wrap helps retain moisture and increase humidity during germination. After your seedlings emerge, remove the cover. A spray bottle or mister is a great way to keep growing media moist without damage to seeds and young seedlings. Check regularly to prevent seeds and seedlings from drying out.
Temperature: Optimal media temperatures for seeds to germinate will vary for each variety. Once the seeds germinate, room temperatures of 70º–75ºF will help the seedlings grow best. Warm season plants such as tomatoes, eggplants, and peppers appreciate warmer soil conditions and may benefit from the use of a special heat mat when sown indoors.
Light: For best growth, seedlings need at least 16 hours of light per day. Even your sunniest window may not supply enough light to grow strong plants. To provide adequate light, we recommend using a shop light with a mix of cool- and warm-white fluorescent bulbs placed 1–2 inches above the seedlings. You could also purchase special grow lights. To make it easier, plug your lights into a timer that is set to turn on and off automatically.
Circulation: Air circulation around seedlings can help prevent disease problems while strengthening seedlings. A fan on low setting will create the needed airflow.
Fertilizer: A water-soluble fertilizer may be used when seedlings have at least two sets of true leaves. Check the label for the recommended rate to mix for seedlings and transplants.
Hardening-off: This is the final step before planting your seedlings into the garden. It is a one to two week transition period that helps the tender seedlings adjust to outdoor conditions, including exposure to direct sunlight, wind, and changes in temperature. On the first day, put seedlings in a protected location out of direct sun and wind. Leave them outdoors for one to two hours then bring them back indoors. Each day, leave them outdoors longer and gradually move them into more exposed areas. Make sure to frequently check the soil moisture.
Gardening from seed is very rewarding. On the inside of every Botanical Interests seed packet you will find the best growing conditions for the variety. We provide information about special care, organic gardening methods, and tips to improve your garden throughout the seasons. Use our garden journal templates and lists to help you keep track of which seeds you started and when. By following these guidelines and keeping a journal, all that’s left to do is watch your seeds grow into viable and healthy plants!