aphids would be my guess...they love nasturtiums!
I use Safer's soap or even just a blast of water on them. You have to keep checking for aphids throughout the summer.

I had that problem last year. Fortunately,the large number of aphids might attract lady bugs whose larvae eat those aphids and any other ones in your garden.

I haven't had a chance to try Safer's Soap yet, (hopefully I can get some tomorrow) but in the meantime, the pyola and the spray of water doesn't seem to be working. The plants are turning yellow and looking pretty bad. Can I cut them back without harming them to encourage new, bug-free growth? And if so, how far back? Ths is discouraging as they were so gorgeous up to this point.

Thanks!
:)
Dee

Oops, I forgot to say thanks for helping me out, Franeli and Jimcnj. Please excuse my bad manners, lol!

:)
Dee

Sounds like the entire plant is infested, not just some of it(?)
All the leaves yellowing?
I've been picking off yellowing + grasshoper chewed leaves
(yes, I have squadzillion grass-my-as$hopers here in the re-clamined gravel yard) and the plants just keep puting out new growth + blooms.
Dry, hot weather is very stressful for nasturtiums. You have that in Conn. this summer?

Hi Franeli. Yes, the entire plant is pretty much infested. I have 3 plants in a large pot, and one seems to be doing okay - only a few bugs and still green and good looking. One is so-so, but the third is just absolutely covered in these bugs and the leaves are yellowing. There is no evidence that I can see of actual chewing or bitten-off areas. In general, the weather has been very warm and very humid, although today it is pouring and has been all day. Maybe this rain will wash away the bugs, lol!

Thanks!
:)
Dee

I had the same problem last year. Second year gardening at all. I got so grossed out pulled them, put them in a bag and tossed them right out. Not knowing that upon inspection I would find some sort of aphid/thrip/earwig/slug..... that I inspected I didn't grow them this year for that reason. Yuck and good luck.

i found the same bugs, sprayed with no success, some suggested purchasing lady bugs, should I?

No. Ladybugs won't be charmed into staying where you want them to upon release. Continued spraying with plain water or insecticidal soaps will keep them in control. Allow the normal population of beneficals seek out and find the aphids in your garden.

My experience is that once they are covered with the things, noting gets rid of them!!! I don't find nasturtiums to be long lasting annuals in the hot humid summer here in Ontario. I don't start them early because of this. I buy a few to put in the post early, then plant a few seeds every 3 weeks or so that way I will always have new plants on the go to take over from the old ones. They are expendable to me. I actually grow nasturtiums to keep the aphids AWAY from the things I really care more about like my roses. When they start to look infested, I tear them out. Sorry, I wish I could be of some help. Keep spraying if you really are attached to the plants otherwise, rip them out and grow new ones.

I love nasturtiums so not growing them is out of the question. Last year I tried an experiment and just kind of ignored the aphids. I did hose some of them once and awhile but no spray. They were fine. Maybe not as floriferous early on but they are always much better here in the fall anyway. Another thing is I also started just direct sowing them which might explain everything.

I do not see any bugs on my nasturtiums, though there are lots of little holes in the leaves. So, something must have eating them.
Also I have a question about some leaves yellowing. Are there any nutrients that are missing, lack of water, or it is normal? I do remove the yellow leaves to keep a better flower box appearence.
Thanks!
Natalie

I seem to be able to grow just about everything successfully except nasturtiums. I have aphids and yellow leaves, three plants in an 8 inch clay pot. Some say they don't need to be fed others say they do. They aphids seem to be sucking the life out of the plants.

Home remedy for aphids: You can kill aphids by spraying, especially under the leaves with a solution of 2 tsp mild dish or laundry soap to a bottle of luke warm water. The soap washes off the aphid's protective waxy coating and causes dehydration. I found this remedy elsewhere on the web and will try it today.