Gardening Articles: Care :: Seeds & Propagation
Gardeners: Start Your Seeds!
by Bruce Butterfield
The Director of Research here at the National Gardening Association, Bruce Butterfield is widely known for his understanding of gardeners and the gardening world. But few outside this building know of his passion for starting seeds. For 10 weeks every spring, at a cost of $50 for seed, soil and pots, plus $70 for electricity, he starts more than 500 plants. Why? As Bruce notes, "It's pretty magical to have hundreds of seedlings pop up while it's still lousy outside. Besides," he adds, "it makes me a better gardener because I'm in touch with the entire process."
1. Sow the Seeds
I use 2-deep plastic flats with multiple water holes in the bottom and fill them with a dry soilless growing mix, firming it down until it is 1/2 from the top of the flat.
Sow seeds in furrows three times as deep as the seed's diameter. If seeds need light to germinate, cover them very lightly if at all.
Space small seeds 1/8, medium seeds 1/2 and large seeds an inch apart. Space rows 1-1/2 to 2 inches apart to allow seedlings room to grow their first true leaves before transplanting. Label each row with the name of the plant and variety, and the date of sowing.
2. Keep Flats Moist and Warm
I set planted flats in a waterproof tray filled with 1/2- to 3/4-inch of water. Because the watering is done from the bottom of the flat, seeds don't get washed out or disturbed. The trays also provide a water reservoir that can help keep your growing medium moist but not soggy. Tepid (65° to 70°F) water is best. Never allow the soil to dry out completely.
To maintain humidity during germination, I place the flat in a plastic bag, cover it with plastic food wrap or use a plastic humidity cover. I don't seal the flat completely, as mold may form if air can't circulate.
Seed flats need bottom heat of 75° to 85°F. I place my flats on top of the fluorescent light fixtures, but you could also put them on top of a refrigerator or near another heat source, such as a wood stove or radiator. Or use one of the bottom heat mats made for this purpose.
3. Provide Light
Once seeds germinate, they need light. I use fluorescent bulbs that are specifically designed to provide plants with as much of the solar spectrum as possible. Each of my fixtures holds four fluorescent bulbs. I also tape pieces of reflective Mylar ("space blanket") to the fixtures' sides to concentrate light on the plants.
I adjust the height of the fluorescent lights so they are nearly touching the sprouted seedlings, and I use a timer to turn the lights on for 16 hours and off for eight hours each day.
Seedlings need less heat than germinating seeds. Most seedlings will grow best at temperatures of 60° to 70°F during the day and night temperatures that are 10 degrees cooler.