Take an ax to it:
Over the summer, I’m so busy fussing with my garden that a lot escapes me. But by the end of August, when I have quit stressing about all the chores, I take some time just to hang out in it. Perfectionist that I am, it doesn't take me long to start seeing stuff that bothers me...like overgrown plants eating up all the space in the garden.
How did I not notice that those siberian iris in the center of the beds had gotten so hefty? They're taking up all the room - didn’t I divide them last fall? I keep feeding that crambe cordifolia,it has never bloomed and probably won’t - I'm done with it. And yikes! That tall rudbeckia over there in the corner of the bed is crawling all over everything else and crowding out that new batch of perovskia I just put in. Clearly, some things just have to go, others need dividing and moving.
I know doing all of this will make my garden look better and give me room to plant new things, but part of me dreads the idea of doing all that digging and dividing. I’m not looking forward to doing battle with that substantial clump of Siberian iris – just looking at makes my foot and back hurt.
Yeah, just try putting your shovel into one of those babies and you’ll see what I mean. They have massive roots that are thick and very tough to cut into with a shovel. Time to get my trusty little ax out and start whacking away. Don’t gasp - I know it sounds like abuse, but plants with tough dense root stems like siberian iris, hosta, astilbe and hemerocallis can take it. You can use my ax method to divide those enormous clumps of ornamental grasses too, but wait until spring because they don’t like being dug up in the fall.
This is how you do it:
Step 1: Cut down all of the foliage.
Step 2: Take your ax and cut into the plant. You can slice it down the middle, or quarter it. If its really big like this one, whittle it back from the outer edges.
Step 3: Take a slice out of the outer edge of the plant and dig around that part of the plant. Use your shovel to lift the plant out of the ground. It usually comes right up in the size you cut.
Step 4: Take the clump out and remove as much of the soil as you can and put it back around the roots of the mother plant. Keep taking clumps out until the plant is the size you want it to be.
Step 5: Make sure no roots are exposed on the mother plant and tamp the soil back in around it.
Voila you're all done (hopefully,not done in)!
Now you have a bunch of new plants to put in another area of your garden or give away to a friend.