Hollyhocks and rust are always together. In fact, the only way to keep hollyhocks from getting rust is to spray them with a fungicide every week to ten days after they emerge in the spring until hot weather arrives in summer. Rust won't kill your plants, but only make them look unsightly. Keep in mind that hollyhocks are only biennials--they sprout and grow one year and then bloom the next, set seed and die. They often look like they are perennial in nature because they grow back in the same area, but you are looking at new plants developing each year from seeds. Also, always remove all fallen leaves and old stalks because rust can live over in the soil around your plants.