The Master Gardener Articles

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Can you give me information
about starting vegetable and flower seeds indoors?

Some gardeners like to sow their own seed and grow transplants for their vegetable and/or flower gardens. Doing so allows access to a greater variety of plants and cultivars than those found in garden centers in spring. Gardeners should have a schedule in place, know the seed they are growing, and provide good conditions for germination and "growing on" of seedlings.

Clean, sterilized containers, a quality, sterile soilless mix, adequate light, a water source, optimal temperatures, and space are needed in order to be successful. For some seeds, a heating mat will be needed. The gardener also needs to establish a schedule for sowing seed, transplanting, fertilizing, and hardening. Light can be the most limiting factor in raising seedlings in homes, so most gardeners use shop lights (fluorescent tubes) suspended a few inches above the seedlings as a light source. Sterile conditions in the soilless mix and containers are essential; a fungal disease, known as "damping off" can attack and kill young seedlings if dirty containers or native soil is used.

Once the supplies and equipment are in place, the gardener needs to know a bit about the seed to be sown. Some seeds have hard seed coats that need to be "scarified" before they will germinate. This might involve nicking the seed coat with a knife, shaking seeds in a container with some stones, or using sandpaper to roughen the seed coat. Soaking seed is another technique to soften the seed coat. Other seed might require a cold treatment to break the embryo's dormancy inside the seed; this is called "stratification." Usually seed is sown in the soilless mix and then the tray or container placed in a refrigerator or other cool location for a prescribed period of time.

Some seeds germinate in dark conditions, so these are sown beneath the surface of the soilless mix. Others require light in order to germinate, and these are sown on the mix surface. Again, the seed packet will usually indicate the light requirement of the seed.

It's important to know when to start seeds inside so that your plants are "finished" and ready to plant at the right time outside. In central Ohio, even though the frost free date is considered to be April 30, the "safe planting date" for tender plants is about May 15-20. This allows time for clay soils to warm so transplants don't sit in cold soil and root systems rot. Of course, some plants are tolerant of cooler temperatures and can be planted earlier - again the seed packet usually indicate this. Don't be overly eager when growing transplants - there is nothing more frustrating than having finished transplants too early! Then the gardener has to hold them until the safe planting time.

A few dates on starting seed for the vegetable garden; broccoli and early cabbage are usually started inside about February 20. Eggplant can be started about March 20. Tomatoes and peppers can be started about April 1. Many annual flowering plants are started in the March/April period; check seed packets for information.

Remember to harden tender plants before installing them in the garden later in May. It takes about a week or ten days to acclimate plants to outdoor conditions. Gradually expose plants to more sunlight, cooler temperatures, and less moisture over this period. Failure to harden plants can lead to sunburn, wilting, root stress, and possibly death.

The Master Gardener Offers horticulture advice and tips, focusing on current issues by volunteers who are with The Ohio State University Extension, Union County Master Gardener Program. For answers to gardening questions, call 937.644.8117 or e-mail gmcvey@ag.osu.edu. Hourse are 8 a.m. to 4:30 p.m. Monday through Friday