For one thing, nasturtiums don't like heat. They are best planted VERY early here, and will peter out by mid-summer.

I've been trying for years to grow nasturtiums but this is the first year I've had any success. I planted out pre-started seedlings that I bought at a nursery, got them in the ground early, and they grew, and grew, and grew... mostly foliage, and what flowers the produced were hidden under the leaves. I didn't fertilize them at all so I think my soil must be too rich for them. They grew so big, and so fast, that they were threatening to smother my other plants so I yanked them out!

Heat huh! well now I know to get started early for next year, thank you!

I have to say, for the past few years, I have had them in my veggie garden and to be honest, they didn't get going until just about this time of year, every year. This year, I got them at a local herb farm, early in the season since I always felt they are a cool weather plant, and low and behold on the tag it says "grows best between temps of 65-85 degrees". Cool weather? Maybe to someone 85 is cool, but it felt pretty darn hot the other day. So I say they do just fine in the heat too.

Of course that doesn't help the rust problem. I suspect over fertilizing/watering may be the culprit...

Remember that the same people who write generic plant tags with broad temp ranges also write the signs for perennials which say 'blooms all summer!'.

Nasturtiums are cool weather plants. They do well in areas with moderate temps throughout the summer, but won't thrive in this area of hot summers. And they'll do better in some shade here if you must grow them.

I also wanted them to help out in my veggie beds. Maybe I'll try another packet of seeds in the Fall. Thanks, next year I'll treat them like lettuce and see what happens.