— Jamie Stang, Wright County Master Gardener and Master Food Preservation Specialist, Crow River Food Council Member
Starting seeds indoors can be a great “pick me up” during the short, cold days of February and March. Growing your own seedlings is a great way to try out new or unusual varieties of vegetables that you may see in seed catalogs but are not available at your local nursery. It can be more economical than purchasing seedlings, especially if you have a large garden or if you share seedlings with family and friends.
Growing plants from seeds is easier than most people think. The trick to successful seed starting is planning ahead so that your seeds have adequate time and optimal conditions for growth. Most seeds need 4-8 weeks of indoor growing time before they are ready to plant out, so March is the ideal seed starting time for Minnesota gardeners.
Seeds should be starting in a space that has good air circulation but doesn’t have large temperature fluctuations or cold drafts. While many people are tempted to start plants on a sunny windowsill, the radiant cold and heat fluctuations are not good conditions for seedling growth, and many windows provide inadequate light. A basement or interior corner of the house that is lit with artificial lights can be an ideal location for seed starting.
Both florescent and LED bulbs can be used in place of commercial “grow lights”, which tend to be more expensive. The use of either two “cool” spectrum or a “cool and natural” spectrum combination of lights will provide adequate light for seedlings. Plants that emerge should be 2-4 inches from the light, so it’s important that either the lights can be raised and lowered by hanging them from adjustable chains, or that shelves can be adjusted as plants grow taller. Seedlings need at least 8 – 12 hours of darkness each day to mimic outdoor conditions. An automatic timer can be useful in assuring adequate but not too much light exposure.
The use of heat mats is beneficial for starting seeds, especially for seeds such as tomatoes, peppers, eggplant, basil and other plants that prefer warm soil conditions. Electric heat mats are available online and where seed starting supplies are sold. Heating pads sold for human use are not safe around moisture and do not provide the same level of temperature control, so they should not be used.
The best soil to use is a seed starting mixture, which is lighter than typical potting soil and is easier for tiny roots to establish themselves in. A mixture of seeding start mixture and a light texture potting soil can also be used. Because these mixes are light, they dry out quickly. But it’s also important not to overwater, as tiny roots will decay quickly in wet soil. Water lightly every day or two and check the soil about ½ inch below the top to see if moisture is needed. Spraying the seedlings with a misting bottle can be helpful in dry, indoor conditions.
Seeds should be started in small individual containers. Several seeds can be planted in each space, then thinned out as needed. Domed covers that have openings to allow for air circulation can be very useful as they help keep moisture from escaping while also allowing light in. They also help to retain heat. If used, you will want to check to make sure that excessive moisture doesn’t build up and harm seedlings.
Seedlings should be hardened off about 2 weeks before you plan to plant them into your garden beds. Start by putting them outside in a sheltered location for a few hours, then bringing them in overnight. Gradually increase the exposure to direct sun and the time outside until the temperatures are right for planting.
You can find more information and resources for starting seeds at home at the University of Minnesota extension website.