Released March 6, 2008
Starting seeds indoors can give you a head start on Maine’s short gardening season. It also allows you to choose from the much broader array of varieties offered by seed catalogs; commercial plant growers are limited in the number of different varieties they can produce for sale. (Be aware that some plants, including beans, beets, carrots, corn, peas, spinach, turnips, and zucchini, do better when direct-seeded in the garden.)
Supplies
Seed: Use fresh seed from a reliable source. Only use seeds saved from a previous year if they have been stored in a cool, dry place.
Containers: Seeds may be planted in any clean, 2- to 3 1/2-inch deep container with adequate drainage holes. Containers that have been previously used for planting should be thoroughly cleaned and disinfected with a 10-percent chlorine bleach solution, to help prevent disease.
Growing medium: Seeds should be germinated in a fine-textured soil-less mix with no fertilizer. Potted garden soil is not recommended for germination—it may contain weed seeds or diseases, and it tends to compact, dry out, and crust over too quickly for fragile seedlings.
Once seedlings have emerged and developed one or two sets of true leaves, you can transplant them into a slightly larger container with a coarser seedling-growing mix.
Planting Seeds
Time your plantings based on how long the seedlings will take to become mature enough to be transplanted into the garden. Check the information on the seed packages, and then count back from the estimated last spring frost date for your area. Last frost dates for most of Maine are in late May or early June—check with a local nursery. Since seeds vary widely in how well they germinate, plan to sow extra.
Fill containers with moist growing medium and press seeds onto the surface, following package directions for depth. Label the container, and cover it with clear plastic.
Most seeds need warmth to germinate, usually a soil temperature of 65°F–70°F. Find a warm spot in the house, like on top of a refrigerator or near a wood stove, or use heating cables or mats.
Growing Seedlings
When sprouts appear, remove the plastic cover and move the seedlings into bright light. They need 14 to 16 hours per day of natural or fluorescent light to keep from becoming leggy. The growing temperature should be about 55°F–65°F, so avoid drafty windowsills. Many people use grow-light frames that suspend fluorescent lights over the plant trays.
Once the second set of leaves appears, water with a half-strength solution of fertilizer; you can use a water-soluble all-purpose plant food. Gradually increase the strength of the solution over time. Water from the bottom or use a very fine sprinkler to avoid damaging the tender seedlings. Overwatering contributes to fungal diseases, so wait until seedling trays are almost dry before watering again.
Seedlings should be thinned to at least 1 inch apart or transplanted into individual pots. When transplanting seedlings, handle them by the leaves only. Stems are very delicate, and while a seedling can stand to lose part or all of a leaf, it will not survive with a bruised or broken stem.
Transplanting to the Garden
The young plants will need one to two weeks of hardening off before they go into the garden, to get used to outdoor conditions. Start by setting them outside for a few hours at a time in a protected, semi-shady location. Outdoor temperatures should be at least 45°F. Gradually increase the time outdoors and the exposure to direct sunlight. Transplant your seedlings to the garden in the cool morning hours or on a cloudy day, and water them thoroughly.
This column was excerpted and adapted from “Starting Seeds at Home,” a new bulletin from University of Maine Cooperative Extension. Visit UMaine Extension at http://www.extension.umaine.edu/ and click on “Publications” for information on additional topics.
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http://extensionnews.blogspot.com/2008/03/extension-excerpts-from-university-of.html
Contact: Jennifer O'Leary, (207) 353-5550, 1-800-287-0274 (in Maine) or joleary@umext.maine.edu
