Start the impatiens seeds in mid to end march. February is way too early in your zone.

Initially, moisten the seed growing medium with water in a plastic bag. Add water a bit at a time and work it into the mixture using your hands on the outside of the bag. Just add enough to moisten it without making it too wet. E.g. it should be wet so it hold together in a clump when squeezed, but no water should drip from it was you squeeze it.

Take the pre-moisten media out of the bag, and fill the cells in the flat. Just put it in, and then tap the tray on the table to "settle" the mixture. Do not press it into the cells with your fingers. Just add mixture and tap to settle. Repeat by adding more mixture if it settles deeply.

When the cells are filled in this way, you can gently - very gently - use your thumb to make a smooth surface on top of each cell. Don't depress the media too much (you don't want to squeeze the air out) but you want a firm surface.

Then use a moist toothpick to transfer the seeds one-by-one from the bag into each cell (one seed per cell). Once the impatiens seeds are transferred, use your thumb again to gently push down the seeds into the mixture. As before, do not press too hard, just enough to squeeze the seeds into the mixture. You do not want to squeeze out the air in the mixture.

Now we get to watering. Remove the cell cavity inserts from the tray, and then fill the tray 40-50% with water. This water should be room temperature or slightly warmer. Do not use cold water, but dont use very hot water either.

Put the celled cavity inserts back into the tray and let the seed starting mixture wick (draw) up water from below. Do not water from the top. Let the mixture draw water up from below.

Once the seed starting mixture start to turn dark brown or black on the surface, you can remove the celled cavities from the tray and put them aside temporarily. Then EMPTY the tray so that no water remain. When the celled cavity inserts have drained, put them back into the tray and cover with the dome.

Now place the domed covered tray (w/ cavity inserts) about 30 cms below fluorescent lights. This distance will ensure that the seed starting mixture warm up slightly (to about 22-25C) without getting too hot. If you place the bulbs closer to the seed starting mixture (e.g. if the fluorescent lights are closer than 30 cms above the domed flat) the temperatures inside the dome may go too high and kill the seeds/seedlings.

Keep the lights on 24/7 for the 7-10 days it takes for the seeds to germinate. You may find that it will take about 5 days for the first seeds to germinate. Once most of the seeds have germinated (e.g. sprouted) crack the lid (dome) open with a pencil for about 1 day. Then remove the lid (dome) all together.

Once the dome has been removed, and the seeds have germinated, adjust the lights so that they are about 1-2" above the top of the green growth. As the seedlings grow, you may have to adjust the fluorescent lights above the tray.

Note: after you have moisten the seed starting mixture originally, sowed seeds, watered from below and let drained, it should not be necerssary to water again until seeds germinate. From this time on you should water every few days. When the seedlings are very small, you may only need to water once per week, but as they grow bigger, it is necersarry to water every 2-3 days.

When you water, follow the same procedure as above:
1) remove the celled cavities from the flats.
2) fill tray 1/2 full with room temperature water
3) put celled cavities into tray to wick up water from below
4) after the top of the surface changes color (start to turn from medium brown to dark brown or black) then remove inserts (cavities) and let them drain
5) empty tray so no water is standing.
6) put cavity inserts back into tray and put below lights.

Do not let the tray stand with water for a long time. Just enough so the top of the media surface start to turn black and glisten. You should not leave water in the tray overnight.

A few key points:
- always water from below. Do not let water stand in tray
- germinate (sprout) impatiens seeds at 22-25F temperature
- squeeze the seeds into the growing media as explained and cover with clear plastic dome. Do not cover seeds with more media. They require slight to germinate
- keep lights on 24/7 until seeds have germinated. Then you can change to a 14-16 hours per day lighting period.

Ken, I have a question for you. Impatiens have re-seeded in many areas of our property. One area I want to increase the re-seeding look. I had hanging baskets and the little darlings seeded in the pea gravel below (on the edge of a private gravel road). This area will never be a proper planting bed. I recently bought bulk impatien seed. I was thinking of scattering seed in the pea gravel to increase the seeding. Any thoughts to the success of this idea. In Zone 7, what month would you attempt this. TIA, Suz

Do this on/around last frost date. I am not sure how long a growing period you get out of it in your zone (in our zone 6b, they would germinate in june and not flower until august).

Thanks for the quick answer. Nothing ventured, nothing gained. 10,000 seeds - have to give it a try. I'll let you know. Suz