Grow Your Own Transplants
by Don Janssen, Extension Educator
If you can provide the right combination of conditions for germination and growth, you can grow your own flowering annuals for transplanting outdoors after the danger of frost is past.
Light is usually the limiting factor in growing annuals indoors. Without a greenhouse or a coldframe, plants usually can't get enough light for good growth.
The right conditions for germinating seed are usually easier to come by indoors. Clean and sanitized containers, a sterile soilless mix, water and warm temperatures are the key ingredients.
Containers and medium must be free of disease organisms because the moist, warm conditions that favor seed germination also are ideal for growth of fungi and other disease organisms. The medium must be kept moist but not sopping wet -- if it's allowed to dry out, germinating seeds may be killed. If seedlings get so dry that they wilt, their growth will be retarded for several days. Too much water is also a problem. Roots need air as well as water and they will not survive long in saturated soil.
Most flower seeds germinate best at a temperature of 75 degrees F. Though this is warmer than most people keep their houses, there are usually warmer spots such as on top of a refrigerator or above a heat register or radiator where warmer temperatures are available. Using heat cables under containers is another option.
Sprinkle small seeds (mix them with sand for easier distribution) on the moist medium; place larger seeds. Most seeds should be lightly covered; others should be left uncovered. Be sure to check the information on the seed packet before covering seeds. Then cover the container with a clear plastic bag or plastic food wrap and place in a warm spot until seedlings appear.
The plastic conserves moisture and promotes quick germination. Once seedlings appear, the cover should come off to reduce the likelihood of damping-off, a fungal disease, and to keep seedlings from become spindly.
After seedlings appear, move containers to a slightly cooler spot that receives bright light. Water as needed to prevent wilting, and fertilize every two weeks with a houseplant fertilizer. Thin and/or transplant when seedlings get their first true leaves so plants are 1 inch apart. Transplant after that as needed to give plants room to grow.
Acclimate transplants to the outdoors by setting them outdoors on balmy spring days for gradually longer periods each time. They may dry out quickly, especially on breezy days, so check them often and water as needed. When the danger of frost is past, transplant them into the garden on a cloudy day or in the evening so they have a chance to recover somewhat from transplant shock before they have to cope with the full range of outdoor growing conditions.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office