How to sprout seedlings to life indoors

Last Updated: 
March 3, 2010

Planting and watching garden seeds spring to life on a greenhouse bench is one of the most rewarding events in a gardener's year. But what do you do if you don't have a greenhouse?

It's easy to start seeds on a sunny window sill or in a dark, dingy basement under a row of lights, according to Joyce Schillen, Oregon State University Master Gardener.

"Some plants need longer growing seasons than we have around Oregon," explained Schillen. "Starting them indoors gives them a jump on the season. Also, some rather magnificent plants are available only in seed form."

Schillen offers some pointers for starting seeds early in the spring for later planting outdoors in the garden:

  • Don't start seeds too early. "Seed packets usually tell you how many weeks to start seeds before transplanting," she said. "They usually say something like 'six to eight weeks prior to setting out after danger of frost is past' or something similar. Count backwards from the recommended time to determine when to start seeds indoors."
  • Don't start seeds in regular garden soil; use soil-less starting mix or sterile potting mix. "Starting seeds indoors with soil from the garden is the surest way to introduce fungi that cause 'damping off' diseases," warned Schillen. "You know you have this problem when tiny seedlings keel over in patches, or when a fine, cottony wool grows over the soil surface, eventually killing the little plantlets."
  • If a "damping off" fungal infection occurs, spray the seedlings and soil surface with chamomile tea. To make, pour one cup boiling water over one-fourth cup dried chamomile blossoms (available where bulk herbs are sold). Let sit until cool, and strain into a spray bottle. "Chamomile has antifungal properties that create virtual miracles in the greenhouse," said Schillen.
  • Keep soil uniformly moist but not soggy.
  • Maintain the air temperature at 65 to 80 degrees for best results. Provide bottom heat with heat tape, a heating pad protected from moisture, or even a heated waterbed to speed up germination.
  • Provide plenty of light after seeds germinate. When using a sunny window, turn plants daily to prevent a permanent tilt as plants stretch towards the light.
  • If you're using indoor lights, place them very close to seedlings - no more than six to eight inches above the plant tops. "By suspending shop lights on chains, you can raise them up as plants grow," said Schillen. "Cool fluorescent fixtures are sufficient, although full-spectrum lighting may be used if available. Keep the lights on 16 hours a day."
  • Begin fertilizing, at half strength, when the seed leaves begin to turn yellow. "Don't waste your money with fertilizers from the start," she said. "Seeds contain all the nutrients they need to begin growing."
  • Thin seedlings so they have plenty of room for their roots to grow. "It's hard to do, but it's absolutely essential," stressed Schillen.
  • Do not keep plants in pots too long. Some plants, especially fast-growing ones, resent being stymied during intense growing periods. They will not grow as well after sitting too long in pots.
  • Harden off seedlings before planting them outdoors. Slowly introduce them to sunlight, wind, and cooler temperatures over a period of a week or so before planting outside.
Author: Carol Savonen
Source: Joyce Schillen