Q.if my hollyhocks have gotten rust will that stay with the plants and soil,
I have a large bed of hollyhocks and this year we had so much rain and I didn’t remove enough plants this spring and they have rust, will this stay over winter in the soil. If I try to save the seeds to start again will they carry the rust over?I have so many beautiful colors and hoped if I remove the plants after I collect seeds will the rust stay with the soil. The nursery told me to use copper sulfate, but so far not working.
Many people recommend copper sulfate, but I have found a much more effective method. Wettable sulfur and dolomitic lime. Adding these together will kill off most tough infections. Keep in mind that hollyhocks are biennial. The first year is vegetative growth, and no flowers. The second year is a flowering spire. These will bear seeds which will start the process over. It is likely that the issue will resolve its self over a few years, but you can speed this up with the treatment mentioned.
This article will give you more information on the plant: https://www.gardeningknowhow.com/ornamental/flowers/hollyhock/tips-on-hollyhocks-growing-hollyhocks-successfully.htm