While the weather outside is currently cold and snowy, spring isn’t far away. This is a great time to get a jump-start on spring planting by germinating seeds and starting flower and vegetable plants indoors.These methods do have some pitfalls, however.
Here are some tips from Iowa State University Extension and Outreach horticulturists on the proper way to start seeds and plants indoors. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.
The seeds that I start indoors germinate poorly. Why?
Poor or erratic germination of seeds may be caused by improper planting (for example, planting too deeply), uneven moisture or cool temperatures.
Fine seeds and seeds that require light for germination should be sown on the surface of the germination medium and then lightly pressed into the medium. Cover all other seeds with additional potting mix to a depth of one to two times the seed’s diameter.
Uniform moisture levels are required for optimum seed germination. To maintain uniform moisture levels, place clear plastic food wrap over the containers. Flats also can be covered with clear plastic domes. Remove the plastic food wrap or dome as soon as germination occurs.
Most seeds germinate best when the medium temperature is 70 to 75 degrees Fahrenheit. Placing containers in a warm location in the home, such as on top of a radiator or near a heat register, usually provides suitable germination temperatures. In cool environments, electric heating cables or mats can be used to ensure warm medium temperatures.
The flower and vegetable plants that I start indoors get tall and spindly. Why?
Tall, spindly growth is a common problem when growing transplants indoors. Poor (insufficient) light, excessive watering, high temperatures, excessive fertilization and crowded growing conditions are factors that contribute to spindly growth.
Proper growing conditions should produce short, stocky transplants. Immediately after germination, move the seedlings to an area with a temperature of 60 to 70 F and place them under fluorescent lights (a sunny window usually doesn’t provide sufficient light). A standard fluorescent shop fixture containing two 40-watt tubes (one cool white and one warm white) works fine. Position the fluorescent lights no more than 4 to 6 inches above the seedlings. The lights should be on for 12 to 16 hours per day.
Thoroughly water the seedlings when the soil surface becomes dry to the touch. Seedlings growing in flats should be transplanted into individual pots or cell packs when the second pair of “true” leaves appear. Fertilization should not be necessary if a commercial potting mix containing a slow-release fertilizer was used when transplanting the seedlings. An application of a dilute fertilizer solution once every two weeks should be sufficient for those potting mixes that don’t contain a slow-release fertilizer.
Some of the seedlings that I start indoors collapse and die shortly after germination. Why?
Damping-off is probably responsible for the collapse and death of your seedlings. Damping-off is caused by several different fungi. Environmental conditions associated with damping-off are poorly drained potting soil, overcrowding and excessive watering. Damping-off can be prevented by using clean containers and a sterile, well-drained potting mix, and by following good cultural practices. Wash previously used containers in soapy water, then disinfect the containers by dipping them in a solution of one part chlorine bleach and nine parts water. Sow seeds thinly to avoid overcrowding. Flower and vegetable seeds need an evenly moist potting mix for good germination. After germination, allow the potting mix to dry somewhat between waterings.
Source: extension.iastate.edu