Impatiens are excellent plants for shady areas in the home landscape. Impatiens are ideal for flower beds, planters, and hanging baskets. Their versatility and adaptability to shade have made impatiens one of the most popular annual bedding plants in the United States. Impatiens are relatively easy to grow from seeds.
Timing
Impatiens are slow growing. Home gardeners should sow seeds in early to mid-February to produce stocky transplants by spring.
Containers and Media
A commercially prepared medium, such as Jiffy Mix, is a good germination medium. Containers used for starting seeds should be clean and have drainage holes in the bottom. Previously used containers should be washed in soapy water and then disinfected with a solution containing one part chlorine bleach and nine parts water. The chlorine bleach solution should destroy any fungi on the container surface that could attack and destroy the tender seedlings.
Lightly moisten the germination medium, fill the container to 1/2 to 1 inch of the top, and firm lightly. Next, moisten the medium thoroughly by partially submerging the container in water. When the surface becomes wet, remove the container, allow it to drain for a few hours, and then sow the seeds.
Sowing the Seeds
The seeds of impatiens are small (There are approximately 40,000 to 60,000 seeds per ounce.), so sowing seeds can be difficult. A wooden toothpick can help simplify the sowing procedure. First, empty the seeds into a small bowl. Then moisten the end of a toothpick and touch a single seed with the moistened end. The seed will stick to the moistened toothpick. Place the seed in the proper location and press it into the germination medium. Cover the seeds lightly with vermiculite or germination medium.
Germination and Care
After sowing, thoroughly moisten the medium again by partially submerging the bottom of the container in water. When the surface becomes wet, remove the container from the water and allow it to drain. Uniform medium temperatures and moisture levels are required for optimum seed germination. Place the container in a warm location in bright light. The temperature of the germination medium should be 70 to 75°F. To maintain uniform moisture levels, place a plastic dome or other transparent sheet or panel over the container. Do not set the covered container in direct sunlight. The high temperatures which may develop in direct sunlight may inhibit or prevent germination. Impatiens seeds should germinate in 14 to 21 days.
Remove the glass or plastic covering as soon as germination occurs. Transplant the seedlings into plastic cell packs, peat pots, or other containers within 7 to 10 days of germination. Then place the seedlings in a sunny, south window or under supplemental lights. An expensive plant stand isn't necessary. A standard high-output full-spectrum fluorescent or LED shop fixture works fine. The lights should be no more than 4 to 6 inches above the growing plants and should be left on for 12 to 16 hours each day. To produce stocky plants, grow the seedlings at a temperature of 60 to 65°F, keep them on the dry side, and fertilize weekly with a one-fourth strength houseplant fertilizer solution.
Harden the plants outdoors for 7 to 10 days before planting them into the garden. Place the plants in a shady, protected area for 2 to 3 days, then gradually expose them to a few hours of sun. Plant them into the garden after the danger of frost is past.