Starting seeds indoors is a simple and inexpensive way to enjoy many vegetable varieties not commonly found in garden centers. Also, with the shorter growing season in Colorado Springs, starting seeds indoors allows gardeners to “jump-start” long-season crops.
Here are 10 steps to starting seeds indoors:
Select your containers. It's best to use small, individual, divided containers to reduce root damage during transplanting. Plant two to three seeds per cell – when seedlings emerge, thin to one per cell. To avoid disturbing roots, thin unwanted plants with tweezers once true leaves have formed.
Using warm water, moisten a large bucketful of a soil-less seed starter mixture – germination mix – or use equal parts peat moss, vermiculite and perlite. Fill your clean containers with the mixture to just below the rim. Do not use potting soil or compost. Use only sterile mixes to avoid damping off – a common soil born fungal infection and weed seeds.
Plant your selected seeds according to the seed packet instructions.
Cover containers with plastic, and prick holes with a toothpick for ventilation.
Water newly started seeds carefully with a mist sprayer with cool to lukewarm water – 68 to 77 degrees Fahrenheit. A mist sprayer will dispense the water effectively without causing too much soil disruption. Do not allow seeds to dry out, and keep them moist, not soggy.
Seeds sprout best at temperatures of 65 to 75 degrees Fahrenheit. Use plant heating mats available at your garden center or online to maintain the temperature.
When seedlings emerge, remove the plastic and heat mat and move the containers into bright light. A windowsill is often not a good location for starting seeds due to temperature and light fluctuations. Inadequate light is the major cause of elongated, skinny stems, so it's much better to grow seedlings under full-spectrum fluorescent lights on a self-timer to ensure 12 to 16 hours of light daily. Don't leave the lights on continuously, as many plants need some dark period each night to develop properly. Keep lights no more than four inches above the tops of your seedlings; as close as two inches is ideal. Continue to make sure the plants are kept moist.
After seedlings grow and develop true leaves, fertilize with a quarter strength water-soluble fertilizer to stimulate healthy, even growth.
As soon as the seedlings are large enough to handle, carefully transplant seedlings into a sterile soil-less mixture in their own small pots and keep them out of direct sun for a few days. As they grow, you may have to repot two to three times.
Approximately two weeks before planting outdoors, begin hardening off the fragile seedlings to increase their chance of survival by placing them outdoors, where they will receive direct, gradual sunlight. Start with less than an hour and work up from there. The goal is to eventually have the transplants out overnight. You may want to set a timer so you don’t forget them. Increase exposure to bright sun and spring wind for a few hours each day for a week.
Certain vegetables do better when direct seeded in to the garden soil. Plant beets, carrots, corn, parsnips, peas, radishes, Swiss chard and turnips directly in the garden.
Starting vegetables from seed is a rewarding experience. It can nourish your body and soul.
For answers to urban horticultural questions, contact Ask.Extension.org. You can also follow the El Paso County Master Gardeners on Facebook.com/ColoradoMasterGardeners.EPC/.