It’s funny. What Rundy saw as futility, I see as preventing futility. There’s an old garden maxim, “One year’s seeding yields seven years’ weeding.” Well, the worst “weed” in this particular bed was one of the original flowers I planted here myself: Malva alcea ‘Fastigiata’, also known as hollyhock mallow. Wonderful pink flowers, and lots of them–and every blossom produces copious amounts of seed, all of which germinates, sooner or later. You might at first glance mistake the foliage pictured at left as a clump of coral bells. But these are mallow seedlings carpeting every available inch of soil. I was removing them from a good six feet of flower bed. In some places I could use a tool to cut them off just below the soil surface, but when they were growing close to the garden plants, I had to pull them out one by one. Where the ground had been recently cultivated I could grab them out by the handful with a sideways motion, but in areas that hadn’t been dug up and replanted in years I had to grip each tenacious seedling by its taproot and pull. It was an exercise in futility only if you forget that most of those seedlings would grow up, flower, and create an even worse problem if I didn’t pull them now.
Garden advice-givers will tell you it’s important to match the plant to the site, but it’s equally important to match the plant to the personality and lifestyle of the gardener. Most people think of hollyhock mallow as a low maintenance plant, because once you’ve planted it, you can pretty much forget about it, and it will happily grow and bloom. But, if you are (a) unaware of the need to cut it back before it sets seed (thanks for the tip, Zoey), or are (b) unwilling to cut down flower stalks that are still flowering abundantly, this plant becomes high maintenance by virtue of its many seedlings. In the beginning I met condition (a), but even after becoming aware of the problem condition (b) applied to me. I eventually realized I had to get this plant out of my garden, and leave it to the hedgerows where it bloomed just as well.
Mulch would cut down on the problem, but not eliminate it. Mallows have no difficulty seeding in mulch, though it is easier to pull them out. And they are vigorous enough to grow through it, though not in the same quantities as with unmulched soil. But if the gardener has no mulch on hand, or no time to apply the mulch that is available, it doesn’t solve the problem.
If you look carefully in the first photo, you will see that I still have other mallows growing in my garden. They are offspring of common mallow (Malva sylvestris), which seeds less prolifically in my garden. In the seedling stage, the leaves of the “good” and “bad” mallows are almost identical, but when the “bad” hollyhock mallow gets to a certain age, the leaves become much more deeply dissected. In the top right of the second photo you can see one of these deeply dissected leaves. The common mallows never get those deeply dissected leaves. It’s the only way to tell them apart (without a magnifying glass) before they bloom.
So don’t be afraid to look at your plants with a critical eye. Sure, they may be great plants–for somebody else. You may even like the looks of them, but if they wind up causing lots of trouble, you have to decide if they’re worth it, or if perhaps you can get the effect you want with a plant that’s easier to live with.
More on mallows here.