What if we told you that to invigorate that ratty astilbe (Astilbe spp.), you’ll need to dig it up and hack away at the rootball? Sounds scary, doesn’t it? But, that’s exactly what we do when we divide plants and the purpose is both to breathe new life into the plant and to propagate it. Although it may be a bit frightening the first time, it is easy to divide astilbe
Astilbe is a perennial plant, popular for its ability to not only grow in the shade, but produce a prolific bouquet of gorgeous blooms. If you are a U.S. Department of Agriculture plant hardiness zones 3 through 9 gardener with a moist, shady spot in the garden, you will love astilbe.
If you already grow them, and yours isn’t performing as it should or it’s looking a bit faded, it’s time to divide it.
What you’ll need to divide astilbe
Gather up the necessary equipment to divide the astilbe and let’s get started.
- Pruning shears
- Pruning saw
- Household bleach
Dividing any plant requires careful preparation. First, decide where you’ll plant the new astilbes and water that area deeply (moisten at least the top 5 inches of soil) the day before you will be dividing the plant. Water the mother plant as well. Clean and disinfect your equipment (shovel, pruners and saw) in a solution of three parts of water and one-part household bleach. Give them a 5-minute soak and then rinse with water.
Let’s dig it up
Dig a planting hole in the area where you’ve decided to plant the division. Make it as deep as the plant is currently growing and twice the diameter of the plant.
Now, it’s time to dig up the astilbe. Insert the shovel’s head as deep as possible at the astilbe’s dripline. Remove the shovel and repeat the process next to the first insertion and keep repeating until you’ve encircled the plant. Then, gently pry the plant from the ground with the shovel. Shake the soil (gently, please) from the roots.
Use the pruning shears to cut the astilbe’s stems to 3 inches of the rootball, then, use the saw or a sharp knife to cut down the middle of the rootball. Use your hands to pull it apart. By the way, if you need pruners, one of our favorites is frequently on sale at Amazon. You’ll find it here.
Plant one of the clumps into the prepared hole and the other in the original hole.
Replant one of the clumps back into the original hole and wrap the other in damp burlap to keep it moist and cool while you prepare the new planting hole. Apply a layer of mulch around each astilbe, keeping it at least 3 inches from the base of the plant. The mulch will help keep the soil moist.
Water both plants slowly and keep the soil moist (not saturated) while they become established. With these plants, mulching is important, especially if they are planted where they will get some direct sun. Bark chips or any other good moisture-retaining top mulch will be very helpful in maintaining the constantly-moist ground they prefer.
You can divide astilbe every year but don’t wait any longer than three years.
If you’re interested in growing astilbe, Holland Bulb Farm offers a Mixed Astilbe Value Bag, with eight plant starts in an assortment of colors.