How to Prevent Rust on Your Hollyhocks

Hollyhock

I love hollyhocks, cheerleader pom poms, scaffolding of the garden. But I admit they do make me think of that Absolutely Fabulous episode when Eddie says to Saffy…

“I hate those flowers. Those. Those flowers there. They’re too English. It’s about simplicity and sort of Japanese efficiency. The land where they haven’t even got time to let the trees grow tall, dahling. No theater and no time for petals in my life. I want stems.”

Hollyhocks are biennials—they grow one year, bloom the next, then go to seed and die. They may seem like perennials, but the flowers you see in the spot where they bloomed the previous year are actually its sprouted seeds. They do have long tap roots which make them drought resistant, but make transplanting difficult.

The yellow spots on the leaves above are a fungus called Puccinia malvacearum or RUST. Unfortunately, fungal disease can only be prevented, not cured. Last summer, as soon as I saw leaves with rust, I picked them off and put them in the garbage and made sure they didn’t fly out again. This went against all my instincts, throwing away green, and sending fungus off to a landfill, but I didn’t feel right running across the street and adding them to my neighbor’s brush fire. By the end of July, I had pretty much cut all the stems down to the dirt because the rust was out of control.

There are only so many things you can do to prevent rust:

  • Good air circulation
  • Don’t let water get on the leaves (except rain of course)
  • ALWAYS water your garden in the morning so leaves have a chance to dry so fungal creepers don’t have a medium in which to spread around and fester.
  • Use mulch to suppress weeds and retain moisture
  • Use good loamy soil with a dose of composted fall leaves
  • Spray the new growth with neem oil in the early spring every 10 – 14 days
  • Rust is not so terrible until it gets out of control and actually inhibits the ability for the leaves to photosynthesize, so you can live with a couple yellow dots, right?

 

3 responses to “How to Prevent Rust on Your Hollyhocks”

  1. Casa Mariposa Avatar

    I love hollyhocks but gave up growing them because of the rust. However, they were one of the first flowers I grew when I started gardening and have a special fondness for them. I’ve never heard that wood mulch came from China. I’ve never had a problem with mine.

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    1. Amy Avatar
      Amy

      Hola Casa Mariposa!
      Well, maybe not all wood mulches are chipped pallets from China, but my favorite Garden expert Mike McGrath is always disparaging the use of wood mulch. He says the whole wood mulch industry came into being only because construction companies were banned from putting their unusable, trash lumber into landfills, so they started dying it and treating it with more chemicals and selling it as mulch. In any case, that’s what he says on his site:

      “Wood mulches can also slow the growth of established plants—and yes, just plain starve new ones to death—by ‘tying up’ the available food in your soil, a process known as “Nitrogen immobilization”. Wood is carbon; carbon always looks for nitrogen to bond with so it can break down into new soil—that’s the principle behind composting. Wood mulches take that nitrogen right out of the soil, out-competing your nitrogen-needy plants. And dyed mulches are the absolute WORST offenders; the wood in these old pallets—chipped up and sprayed with dye—is the worst type for use around plants. Our favorite mulch expert, Ohio State Professor Emeritus Dr. Harry Hoitink, warns that dyed mulch is especially deadly when used around young plants or in brand new landscapes.”

      But if the kind you get works, then it probably doesn’t have nasty stuff in it! 🙂

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  2. Jordi Avatar

    Welcome to Blotanical,
    Un Saludo

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