Summer is not an ideal month for dividing coneflowers because they are in bloom. This means they are putting a lot of energy into flower production and less on roots, making them more vulnerable. If you absolutely have to divide in the summer, do it on a cloudy day and cut back flower heads to promote root development. [4] X Research source After division, keep your plants watered and screen them from the sun for 2 to 3 weeks using mesh netting or another kind of screen.
If you’re dividing your coneflowers from a pot into your garden, make sure the new holes are around twice the pot’s diameter. [6] X Research source
Compress a handful of soil into a ball and gently poke it. If it doesn’t fall apart, it’s too wet. [11] X Trustworthy Source Michigan State University Extension Extension program of Michigan State University focused on community outreach, education, and engagement Go to source Adding another 20 to 25 percent of moisture retaining material like perlite, vermiculite, or peat helps if your soil is dry. [12] X Research source If it’s too wet, mix in 20 to 25 percent horticulture sand, which will improve drainage. Mix in some bone meal to encourage new root growth.
Dig deep into the soil to loosen the roots and isolate the clump. [14] X Research source
Water the soil 2 to 3 days before uprooting to make the process much easier.
Be sure to keep the root system as intact as you can.
If you find any soggy, slimy, or discolored roots, remove them from the rootball with your garden pruners.
Take care not to disrupt the roots unnecessarily.
Sharp spades are much more effective for cutting roots than flat spades. [20] X Research source Don’t divide for the sake of dividing. Gaining 3 or 4 healthy plants is better than 5 or 6 dead ones. Optimal size is around a quarter the size of the original rootball, although you can make them smaller if you don’t have enough space in your garden. [21] X Research source
If you like, you can trim the top of the flower off to promote root growth. In many cases, the top will end up dying following division.
Use deep, plastic or resin pots/containers that contain drainage holes. Make sure they are 2 to 3 gallons (7. 6 to 11. 4 L). [25] X Research source Line the bottom with 2 to 3 inches (5. 1 to 7. 6 cm) of crushed gravel for adequate drainage. [26] X Research source
To maximize your plant’s survival, dig deeper by 6 to 12 inches (15 to 30 cm) and fill it back up with soil. Double digging loosens the soil below the rootball, promoting straight root growth. [28] X Research source Keep the rootball level with the soil surface. [29] X Research source
