Dividing Perennials – Thinning Perennials

Whenever I’ve sold various perennials to folks over the years, one of the most reoccurring questions I’m asked is, “How often do I have to divide them?”

Maybe it’s the way most garden books are written. But I get the feeling that most people think there is a certain amount of time allowed each perennial and then you must divide it.

Fortunately, I never read any of that when I first started gardening.  (I started planting flowers at the same time I started planting vegetables.) By the time I starting reading all that stuff, I didn’t pay much attention to any of it, because the plants had already told me what to do.

That’s correct. Your plants will tell you when they need dividing or thinning as you go about tending your borders and flower gardens.

  • If they’ve taken over more space than what you allotted to them — thin them.
  • If clumps die out in the center, dividing or thinning will bring them pack to peak performance.
  • If they’ve stopped blooming, divide or thin them to get the bloom back.
  • If you want more plants, divide them. (Some you’ll propagate by cuttings.)

And the more you garden, the more the timing (of when to do it) will become second nature to you.

Cool Spring – A Great Time for Dividing

By the Farmer’s Almanac forecast it looks as if cool spring weather will continue into May.
Spring is a good transplanting time anyway, but with this cool weather to slow things down it’s even better, since one of the best times to transplant and/or divide many perennials is when plants are just breaking dormancy.  And they’ll have time to set their roots before the heat of summer sets in.

Also, dividing is almost always easier in early spring (and in late fall) because the ground is usually moist. That makes lifting most perennials a breeze.

Even many late spring bloomers and summer bloomers (which are traditionally divided in the fall in warmer areas like Virginia) can do well and bloom without missing a beat if divided when growth has just begun in the spring.

Some of the Plants I Like to Divide in The Early Spring

Asters, coreopsis, day lilies, rudbeckias, phlox, yarrow, ornamental grasses, ajugas, boltonia, chrysanthemums, shasta daisies, hostas, monarda, various vining ground covers, my old fashion primrose, solidago, lambs ear, and verbena (v. canadensis).

You can dig up whole clumps and then separate them into smaller clumps or individual plants. Some plants have roots that pull apart fairly easily.

Big clumps of plants like daylilies, asters, hostas, and ornamental grasses can be hard to pull apart by hand even after they’re removed from the ground. Sometimes you might need an axe to cut them into smaller pieces. Don’t worry about slicing through some of the individual plants.  You’ll still have plenty intact that will grow.

Sometimes you can use a shovel to slice down and remove sections of the plant without lifting the entire clump.

Important TIP: Resist the Urge to Plant BIG

Most gardeners seem to want the biggest plant they can get but the fact of the matter is you’ll get a better plant from a smaller start. For more about that see my post: Plant Perennials – Is Bigger Better?

Final Thoughts

If you’re new to all this and think you’re gonna mess up stuff, put that out of your mind.  Plants are tough and want to grow.  Just go for it!  And you’ll find that out first hand.

Suggested Reading:

Cuttings – Free and Easy Way to New Plants

Plant Perennials – Is Bigger Better?

Flower Gardens – Flower Borders – Do You Need to Fertilize?


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