Seed Starting 101: Starting Your Garden Seeds Indoors - U of I Extension

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Seed Starting 101: Starting Your Garden Seeds Indoors

This article was originally published on April 11, 2013 and expired on May 15, 2013. It is provided here for archival purposes and may contain dated information.

University of Illinois Horticulture Educator, Kelly Allsup, states there are added benefits to starting your garden seed indoors. Garden seed started indoors has a higher germination rate, produces more uniform growth when placed in the garden, is cheaper, offers better selection and can give you a jump start on the growing season.

Starting seed can be very easy if you remember the three requirements of seed germination: water, oxygen and temperature. Water breaks the seed coat allowing for oxygen to enter. Oxygen is needed to allow respiration. Respiration is required to allow the cotyledon (embryonic shoot) to access the stored energy in the endosperm therefore allowing growth. Temperature plays a substantial role in seed germination because seed will not germinate under temperature extremes. Please follow the following steps for successful garden seed germination.

1. Choose a location to germinate and grow your seedlings. This can be in front of a south facing window in your home, in a cold frame or in a greenhouse. Cold frames can be easily made out of lumber and plastic or purchased in garden centers.

2. Choose seeds and read the germination requirements on the back of the package. Some seeds germinate faster than other seeds. This information is crucial when timing your plants to be ready for the garden. For instance, cucumber, melon, squash, radish, beets, herbs and peas germinate faster than broccoli, cabbage, pepper, tomatoes, eggplant and brussel sprouts. The amount of time to germinate also depends on temperature.

3. Gather supplies needed to start your seed. A plug tray, plastic inserts in a flat that you may have left- over from buying plants or peat pots are the best vessels to start seed. Fill trays with a high-quality germination mix composed of peat moss, vermiculite and/or bark rather than average garden soil to ensure good drainage. Use fluorescent lights mounted over the seed trays or heating pads placed under seed trays to reach optimal temperature for seed germination. Use a water spray bottle to water plants while they are young.

4. Pack trays with germination mix tapping tray on hard surface to ensure all spaces are filled.

5. Use finger to create indention in the soil. Place 1-2 seeds in the divot. The general rule of thumb is bury the seed the same depth of the size of the seed; 1:1. This information will also be on the seed package. Either sprinkle a thin layer of germination mix or push seed down with the tip of a pencil.

6. Use water bottle to finely mist the soil media until saturation.

7. Cover with glass or clear plastic tucking under the sides of the plug tray to ensure moisture at all times. Germinating seeds must be kept moist. Remove plastic daily and only spritz the cells that have dried out.

8. Place the plug tray on heat mats or place lights over them to emit extra heat. The optimal heat for germinating seed is 77-86 degrees. Use a thermometer to determine the temperature of your rooting media.

9. Once one seed has germinated, remove plastic or glass to prevent damping off (fungal disease) of young seedlings.

Congratulations you have germinated seeds like a real professional. However there is more to know to make sure this new seedling makes it to the garden in good health. Please follow the following steps for successful garden seedling care.

1. New seedlings need light. The fluorescent light you originally had to heat the seeds will now provide light for photosynthesis. The best indoor light situation is the combination of natural light from a south facing window and the addition of fluorescent lights. Place fluorescent lights 6-8" above the seedlings.

2. Once all seedlings have emerged, remove plug flat from heating mats.

3. Use water sprayer to individually spray dry cells in plug flat to prevent overwatering.

4. Once first leaves are on the seedling, fertilize with weak fertilizer (1-2 tsp. per gallon of water) using a watering can that is designed to make the water trickle out. Fertilize additional times if plants are slow to start or nutrient deficiencies are evident.

5. Be conscientious of timing. Our last frost free date in Zone 5B is April 15. Cool weather vegetables can be planted earlier and covered if frost comes. Most seeds take 7-10 days to germinate and 2-8 weeks to grow in their plug flat before planting in the garden. This amount of time varies with temperature, light and kind of garden seed.

6. Harden off plants by placing outside for a few days before planting. This allows plants to acclimate to the environment.

Congratulations you are ready to plant your vegetable garden and enjoy the fruits of your labor.

Pull date: May 15, 2013