Starting Vegetables from Seed

If you want to get a jump start on your vegetable garden this year, why not try starting a few plants indoors from seed. There are many advantages to growing your own transplants including selection (a wider variety of plants and cultivars are available from seed than transplants), costs (seed is less expensive than transplants), and quicker results (vigorous plants are likely to flower sooner and produce an earlier harvest). However, growing a seed to transplant size successfully does require time and the proper technique. This article will discuss the steps to starting vegetables from seed.

Before you sow any seeds you first need to determine the date when your new transplants can be safely moved to the garden. This varies for every plant. Some cool season crops, such as broccoli, can be transplanted in March while warm season plants like tomatoes, which cannot tolerate cold-temperatures, should not be planted until after the frost-free date. Once a safe planting date is determined, refer to the seed packet for the number of weeks it will take the seed to grow to a transplant size and subtract that from your safe planting date to determine when to sow your seeds.

Growing your own transplants does not have to be expensive or elaborate. The basic materials needed are seeds, containers and soil mix. Selecting a proper container will help seed development. Seeds may be sown in wood or plastic flats to save space though they will have to be divided and planted into cell packs or individual containers later. Seeds can also be sown directly into divided containers such as cell packs, peat pots, or compressed peat pellets. The later two have the advantage of being able to be planted into the garden when plants reach the appropriate size. Plants with large seeds (i.e., cucumber, watermelon) are good candidates for individual pots or containers.

Regardless of the container, unless it is new, it must be cleaned with soapy water and sterilized with a solution of 1:10 of chlorine bleach to water to reduce disease pressure. Perhaps even more important than containers is your choice of soil or soiless mixes. Soiless mixes include vermiculite, milled sphagnum moss, and synthetic mixtures which combine vermiculite and sphagnum with perlite. These mediums have the advantage of being disease free but they contain no fertility which means they require frequent fertilization with a liquid solution after seedlings emerge. Good garden soil can be added to vermiculite, sand, or perlite to make a soil medium but garden soil requires sterilization.

Your container should be filled to within 3/4 inch from the top with your pre-moistened soil medium. If you are using a flat, you can make shallow rows to plant different seeds in the same flat. If only one type of seed is being used they can be broadcast over the surface. The seeds can be covered with dry vermiculite or sphagnum moss. Refer to the label on each seed packet to determine depth of seed planting.

Slip your flat or individual containers into clear plastic bags to help retain moisture until the seeds germinate and place your container in a warm location but out of direct sunlight. Move the container to bright light when the majority of seeds have emerged. Not all vegetables are suitable for growing indoors as transplants. Those that are easily transplanted include broccoli, cabbage, brussel sprouts, lettuce, okra, and tomato. Cauliflower, celery, eggplant, onion, and pepper are a little slower to develop and require extra care but can be grown.

Light, moisture, fertilizer, and temperature are the factors that are most important in raising a seedling to proper transplant size. Though you may have good light from a south facing window it is generally better to grow seedlings under cool 40-watt fluorescent light tubes. Light fixtures should be attached to chains that can be adjusted to maintain a 4 inch space above the top of seedlings. Don’t leave the lights on continuously as plants need no more than 12 to 16 hours of sunlight daily.

Soil medium should be kept moist but never soggy and be allowed to dry between watering. Don’t allow the seedlings to wilt. Soluble houseplant fertilizer is a good choice for seedlings. Fertilize at a quarter to half strength every other watering for the first few days after the first true leaves appear. Then switch to fertilizing at two-week intervals.

Finally, temperature can play a big factor in size of plants and development time. Most vegetables prefer night temperatures between 60 to 65 degrees. Day temperatures may be 10 degrees higher. Cool season vegetable may need cooler temperatures (55 degrees at night and 65 degrees at day). A commercially available grow mat can be used to maintain an even temperature.

When seedlings grown in flats have developed at least one set of true leaves and are large enough to be handled, they will need to be transplanted to individual pots or cell packs. Here they will continue to grow from 5 to 7 weeks until they are ready to be moved outdoors.

Beginning February 4, 2021, from 12:00 to 1:00pm, I’ll be hosting a weekly Zoom meeting called “Garden Q&A Live”. Feel free to pop in and ask gardening questions or discuss what’s going in your garden during the week. For details visit: www.ChristianCountyHorticulture.com

— Kelly Jackson, Christian County Extension Agent

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