We've had a terrible bout of Impatiens downy mildew in the North Atlantic and Northeast areas. I'm hoping it doesn't reach you. No one here grows Impatiens now, until a resistant variety is found it will be "verboten". It was a great loss to us who use shade annuals for color. I've always used bottom heat for imptiens and begonias. I have not started either since I've left commercial GH. Most of my seeds now come from seed swaps, or our own collection. I do still order heirloom seeds once and again or pick them up at the Philly Flower Show. I still think creating you own microclimate for germination is the most cost effective way to go.
We can still grow impatiens in containers of sterile potting mix, but they may still become infected, the mildew can be wind borne.
