Impatiens are moderately difficult to grow from seed, but a little TLC will give satisfying results.
Impatiens require a warm soil and light to germinate. A soil temperature (not room temperature) of 75 degrees F is perfect. If a constant soil temperature is not maintained during the germination period the seed may rot.
Impatiens seed is fairly large compared to petunia or begonia seed. Under ideal conditions it will show a white sprout in about 5-7 days. Some seed may take a little longer. The white root sprout is the first to slowly poke out; the green bud (the leaf part of the seedling) slowly follows.
How to Plant
Sow seed in a peat-light mix or sterilized, well-aerated soil mix.
Fill the flats or pots (depending on which you prefer to use) full; level and firm around the edges and corners.
Water thoroughly with hot water (100 degrees F or more). Wait 30-60 minutes or more and repeat this procedure.
Let the starting mix cool to a touchable temperature.
Sow the impatiens seed thinly (about 4-6 seeds per inch), by pressing the seed into the starting mixture -- do not cover the seed with starting mixture.
Cover the flat, tray or pots (whichever you have chosen to use) loosely with plastic wrap to hold in humidity.
Place flat, tray or pots on bottom heat. Bottom heat will maintain the proper temperature. Strive for a soil temperature of 75-78 degrees F (but never go over 85 degrees F). If you cover the flats, trays or pots with glass to keep humidity high, you will run the risk of cooking the seeds. It is best to cover loosely to let in some air.
Set in full light.
A mist system may help in the germination of impatiens seed. Be careful not to overdo and drown the seed. Misting may be suspended on cloudy days. Bright, hot days may require additional misting. Use caution, it is easy to overdo misting. Impatiens seed germinates very successfully without the use of a mist system, if covered loosely.