Starting flower and vegetable transplants at home can be fun. Growing quality transplants requires good seed, a sterile, well-drained growing medium, proper temperature and moisture conditions, adequate light, and other factors. Since the home is not always the best environment for growing transplants, problems occasionally develop.
While there are obstacles to growing transplants indoors, home gardeners can produce good quality transplants if they follow good cultural practices.
Poor or Erratic Germination
Poor or erratic germination of seeds may be caused by improper planting (for example, planting too deeply), uneven moisture, and cool temperatures.
Fine seeds and those seeds which require light for germination should be sown on the surface of the germination medium and then lightly pressed into the medium. Cover medium-sized and large seeds with additional potting mix to a depth of 1 to 2 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 can also 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°F. Placing containers in a warm location in the house, such as on top of a radiator or near a heat register, occasionally provides suitable germination temperatures. In most situations, electric seed germination mats can be used to insure warm media temperatures.
Tall, Spindly Growth
Tall, spindly growth is a common problem when growing transplants indoors. Poor (insufficient) light, excessive watering, high temperatures, excessive fertilization, and crowded 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 supplemental lights (a sunny window usually doesn't provide sufficient light). Home gardeners can use a simple standard, LED, 4-foot, plug-in shop fixture with full-spectrum (also called "daylight") light, placed 18 inches from the foliage providing at least 3,000 lumens with lights on for 14 hours a day.
Thoroughly water the seedlings when the soil surface becomes dry to the touch. Fertilize every two weeks with a dilute fertilizer solution. Seedlings growing in flats should be transplanted into individual pots or cell packs when the first "true" leaves appear.
Sudden Collapse and Death of Seedlings
The collapse and death of seedlings is usually due to damping-off. 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, a sterile, well-drained potting mix, and by following good cultural practices. Wash previously used containers in soapy water, then disinfect by dipping them in a solution containing 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 soil to dry somewhat between waterings.
Yellow-Green Seedlings
A nutrient deficiency is likely responsible for the sickly yellow-green color. Nitrogen and phosphorus deficiencies sometimes occur when flower and vegetable seedlings are started indoors. Symptoms of a nitrogen deficiency include yellow-green foliage and stunted plant growth. Phosphorus-deficient plants have purplish leaves. Applying a dilute fertilizer solution once every two weeks should help supply adequate nutrients to the seedlings.
More Information
- Guide to Starting Seed Indoors
- How to Successfully Start Seed Indoors
- Growing Indoor Plants Under Supplemental Lights
- How to Clean and Disinfect Plant Containers
- How to Store Seeds and Test Germination Rates
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