Purdue Extension Service

Vanderburgh County, Indiana

Starting Garden Seeds Indoors

By Larry Caplan, Extension Horticulture Educator, Vanderburgh Co., IN

For the Evansville Courier and Press, January 20, 2008

When it comes to growing vegetables and flowers, many gardeners choose transplants over direct seeding. Vigorous plants started indoors and then transplanted will flower sooner and produce an earlier harvest than those started directly outdoors. Some seed are too tiny to survive being directly sown in the garden. Some home gardeners start their own transplants to save money, and to grow cultivars which may not be available from local garden centers.

Starting your own transplants can be time consuming, though, and is fraught with challenges. Purdue has a terrific publication on starting seeds indoors (call my office and ask for publication HO-14), but here are some important tips I want to draw your attention to.

First, start off with good quality seeds. Buy labeled hybrids from reputable garden centers and mail-order catalogs. Unless you have an old heirloom variety, never save seeds from your garden for replanting...they won't breed true to variety.

Sanitation is absolutely critical. Seedlings are very susceptible to several fungi that cause "damping off" disease. You can lose an entire flat of seedlings overnight because of this. Start your seeds with sterilized potting mix (never use garden soil). Be sure that all flats, pots, and containers have been thoroughly washed and sanitized with a bleach solution before using them.

Timing is important. You want to start your seedlings indoors early enough so that they'll be big enough to transplant in the spring, yet not so early that the plants are overgrown. Depending on the species, you will want to start your seeds indoors anywhere from 4 to 10 weeks before our average last frost in the spring (between April 6 and 15 throughout southwestern Indiana). Several other Purdue bulletins will provide dates for actually bringing these transplants out into the garden.

One environmental factor that is often overlooked is light. Germinating seedlings and young transplants require very bright light. As I learned from my own sad experience, you cannot grow quality seedlings on your windowsill. Even a south-facing window does not usually let in enough light; the young plants will be very weak and spindly as they stretch to reach the sun.

To get around this, you need to supply enough light. Some folks have hobby greenhouses in their yards, which provide enough light (be sure to keep them heated, though). Most other gardeners will use fluorescent lights that can be raised and lowered to provide the right amount of light. A fixture containing two fluorescent tubes is adequate. Use a combination of 1 cool white tube and 1 warm white tube, or splurge and buy "grow bulbs". Place the seedlings 3-4 inches from the tubes, and check them daily to avoid burning the leaves if they touch the bulbs. Keep the lights on for 14 to 16 hours each day, using a timer if needed.

For more information on growing transplants or other gardening topics, contact the Purdue Extension Service at (812) 435-5287.