I think ants aren't widely known as a pest to dahlias. I had ants one year and sure enough they were going after aphids which lined the stems and stalks of a couple plants. Have you checked for green or black aphids?

I don't know what to tell you to do, sorry. But if it is aphids, you can pretty easily take care of them with a brisk squirt of water ( support the plant if you shoot it with the hose, so you don't break the poor thing.) I used a stream from a trigger squirt bottle and that worked too.

My guess is aphids too - the ants like to farm them. Also you didn't mention if they were in a pot, but if so ants seem to take residence in my pots that have dahlias in them...

Trying my first dahlia, it's in a container and I just repotted it - and discovered that the soil is full of ants - you (Kneecop) mentioned this is common, but is it something I should be dealing with? Are the ants harmful at all? I think we had an aphid problem but washed the plant last week and they seem to be gone and the plant seems to be slowly improving. Any advice appreciated.

Thanks.

You need to get rid of the ants as they will chew the stalk in to if they are left alone. I have lost a few plants over the years in this manner from ants.

What works to get rid of ants in a potted dahlia? I can't find them on the plant at all but they're in the soil.

Thanks.

I have dahlia's planted outside in the ground and was wondering why some are doing well and others look sick. I checked and found ants living in and around the stems. I think I may have mulched to close to the dahlia. I moved the mulch away and spread ant killing dust at the base of the dahlia. This seemed to hold them off for a little but I noticed they are building little ant hills around the base of some dahlia. I'll have to try something else.

This is my 2nd year growing dahlias and those relentless ants attack my plants too! I donot have any aphids so I'm not sure why the ants are there. I do know that they are everywhere from the base of the stalk to the leaves on top of the plant. They swarmed one of my newly sprouted dahlia plants a few months ago when it was only 1 inch tall. I've tried several types of insecticides for all sorts of bugs on my dahlias and Sevin seems to be the most potent. The downside is...I heard it kills good bugs too.

I am also new to dahlias this year, and have several large tubers in the ground as well as smaller ones in containers. At the beginning of the summer, I had a horrible ant problem as well. They were eating the leaves leaving gross little white egg looking things on the stems. Anyway, I bought a can of insect powder called Selvin and dusted it over the dahlias. The ants returned several weeks later and I dusted again. Now, about two months later, I haven't had any more problems and the plants are doing very well!!!