Seed starting: Getting a head start in the garden
Gardeners who are anxiously awaiting spring and eager to get their garden planted can get a head start by starting seeds indoors. Many homeowners head to the local nursery to purchase plants that can be transplanted directly into the garden. However, with some extra effort, it is possible to save money and grow your own flowers and produce from seed.
You can scour seed catalogs during the cold winter months, selecting the varieties you want to grow without being limited to those few available in the local garden center. This is an ideal opportunity to experiment with heirloom varieties. You can also select new cultivars that are resistant to common garden pests. The back of the seed packet generally will tell you what year the seeds were packed for, planting depth, the number of days until germination, when to start the seeds indoors, and other valuable information. According to Diane Relf and Elizabeth Ball of the Virginia Cooperative Extension, Virginia Tech, and Virginia State University, only 65 to 80 percent of the seeds are expected to germinate in the first year. This percentage declines in subsequent years.
To grow the seeds, you will need to purchase a seed-starting kit or assemble one yourself. This includes a solid planting tray with adequate drainage and a clear plastic cover. The tray can be set in a sunny window, but for more predictable results, you can place fluorescent lights directly above the tray. Do not use incandescent lights as they project too much heat.
Charles Glass is a Delaware County Master Gardener Volunteer who grows most of his plants from seed. He also sells his produce at the Sunbury Farmer’s Market. He recommends building, or purchasing, a frame to hold several trays with fluorescent shop lights hung on chains above the trays so their height can be adjusted as the plants grow.
For best results, use a seed-starting medium, instead of potting soil. Don’t forget to use plant markers to label the seeds, including the date the seeds were planted. You should also keep a complete record of the variety’s progress throughout the growing season, so you will know what, if any, issues were encountered and whether or not to plant that cultivar again.
Four critical factors affect germination: water (moisture), light (or dark), oxygen and heat.
WATER: prior to planting, Mr. Glass mixes up the seed-starting mixture in a bucket so that it’s damp, not wet or dry. The mixture is transferred to a tray, the seeds planted, and the cover placed on the tray. Ideally, the tray will not need to be watered again until the seeds germinate. This is the most critical time for the planting medium to have the proper amount of moisture. Use your index finger to judge whether the soil is damp or if it needs water. If the environment becomes too wet, remove the cover.
LIGHT (OR DARK): The seeds should be planted as indicated on their package, which is generally at a depth twice the seed’s diameter. Very small seeds are generally pressed into the surface of the medium. The tough seed coat of some seeds, including parsley, must be scarified, or broken, before planting, so that water can penetrate the seed and the germination process can begin.
OXYGEN: The medium in the tray should be lightly tamped, enough to keep the seeds in place, but not enough to eliminate the oxygen the seeds need to germinate and grow. Seeds can be planted in small containers or cell packs and then transferred directly into the garden, eliminating the need to transplant small seedlings.
TEMPERATURE: A seedling heat mat can be placed under the tray to keep it at the correct germination temperature. This mat should only be used until the seeds pop up. The 2010 Ohio Vegetable Production Guide, which is available online at ohioline.edu, contains a germination and growing guide for vegetables and herbs. It lists the optimal germination temperature for each crop.
After the seeds germinate, the plastic cover must be removed. The plants need air circulation and light to grow. Mr. Glass recommends using fluorescent shop lights above the plants for 16 hours a day as a lower-cost alternative to more expensive lights made specifically for seed starting. He also suggests watering the trays from the bottom, so avoid disturbing the seeds.
When the seeds sprout, a pair of cotyledons, or oval-shaped seed leaves, emerges first. They are followed by true leaves, which look similar to the leaves on the mature plant. Then the plants should be transferred from the tray to small containers or cell packs. Mr. Glass minimizes expenses by using recycled plastic containers, instead of peat pots or paper cups. At this point, you should start applying liquid fertilizer weekly. Keep the plants watered and, as the seedlings grow, adjust the lights to stay 3–6 inches above them.
When it is time to transfer the plants to the garden, they should first be acclimated to the outdoors by keeping them in an unheated area of the house for several days. Then, to minimize stress on the plant, put them in the ground on a cloudy day or in the evening, not in the mid-day sun. Some crops, such as tomatoes and peppers, are sensitive to cool weather and should not be planted until the soil is warm. Some other crops, including carrots, radishes, and lettuce, prefer the cool weather. They can be planted as soon as the soil can be worked.
For more information on growing plants in Ohio, visit Ohioline.edu.
Nancy F. Traub is an OSU Extension Master Gardener volunteer.