If 'The Poppy is Also a Flower';* Is the Hosta Also a Weed?
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*Title of a real work by Ian (James Bond) Fleming:
Q. Lynn, in the West Mount Airy section of Philadelphia writes: "I am trying to rid my garden of hosta. Is digging it out the only solution or is there something I can do to kill it without harming other plants or the soil?"
A. I am VERY familiar with hostas and their ability to propagate, Lynn. If left to their own devices, they will form a thicket so dense that several books recommend them as a ground cover, which to me is the ultimate hedging of the language. Yes, they WILL completely cover the ground, but I doubt that anyone would enjoy trying to walk on them.
The good news is that they can be controlled, as I know personally because they are the centerpiece of my front yard, which is heavily shaded and has been hosta-sized since the late 1980s. But before we control this plant, let us first praise it, as it is THE essential element of the Holy Trinity of The Coward's Shade Garden: Hostas, begonias and impatiens (although impatiens are dropping off the shade chart rapidly as a blight continues to spread that wipes out bedding impatiens virtually overnight).
Getting back to hostas, let us review the life cycle of this remarkable plant. A "herbaceous perennial", the individual plants die back to the ground every winter. Actually, like spring bulbs, they die back under ground, and pretty soon you can't see exactly where they will emerge next Spring. But emerge they will, enlarging their 'clump' every season.
They grow rapidly; and soon every plant is sending up a tall central spike that will be covered in sequential flowers mid-summer. The basic form has green leaves and produces purple flowers, while the older variegated species have white variegation and produce blooms that are more a light lavender. In more recent times, hostas have been introduced in a lot of shades: golden leaves, leaves that appear blue, white flowers, flowers that are much more blue than purple.... And hostas easily cross pollinate, so if you grow lots of different colors, a 'sport' may appear in a new shade in your garden. Whoop-de do!
Because of their height and the fact that there isn't all that much else in bloom at that time of the year, hosta flowers are often the focal point of the landscape in summer. And native bees--especially bumblebees--love buzzing into those big flowers for pollen and nectar. (They aren't native plants--they're from Europe by way of Asia--but native pollinators love them.)
Then the trouble starts. Each of those flowers becomes a surprisingly large seed pod, which will burst open at some point and then the birds will come a running. Finches especially seem to like these seeds and return the favor of food by flying off, pooping out some undigested seeds and the most natural fertilizer imaginable; and boom--there's a new baby hosta coming up under your ornamental cherry tree.
This creates a philosophical dilemma--native birds love the seeds and the strikingly tall scapes with their prominent pods provide wonderful 'winter interest' in the garden--but leaving them go to seed can spread these 'easy to grow' plants into the wild (where they will feed more pollinators and birds, stabilize the soil, give toads a perfect place to live...)
I know; I'm bad. I just can't get hyped up about successful and useful plants being called 'invasive'.
Now that I'm in Big Trouble, let's discuss hosta control. Job number one, of course, is to promptly remove the developing seed heads after the flowers fade; then you just have the existing plants in the ground, which I have been controlling for years with a weed whacker.
In a front yard that would otherwise be wall-to-wall hostas, I whack the emerging plants early and often to create walking lanes and to shape clumps. I currently have one rectangular bed where Spring bulbs and hostas peacefully coexist and one giant central bed that's a circle about five feet in diameter that looks amazing in bloom. Everything else named hosta that tries to come up gets whacked.
I also have a stupid fifty-year-old crabapple tree in the middle of my driveway that gets spared the chain saw every season when it beautifully buds out (bright red buds that turn to pink that turn to white) and then carpets the nearby road in apple blossoms so perfectly that somebody should get married there. It is surrounded by a circle of hostas so thick that you don't look up at the tree, which is good, because like all crabapples, it looks like The Dog's Breakfast the other 50 weeks of the year.
Back to control. If you were so inclined, you could certainly dig up each individual plant early in the spring when the leaves first break ground. But you could also just whack 'em. Even though they're shade lovers, they need to photosynthesize, and if you prevent that for a full season, the plants will become puny. The following year, they will begin to disappear. Then you can whack 'em again for a month or so and then cover their spots with a thick mulch...
...except, of course for the clumps you sculpt into really cool designs.