Divide Me Please

Aster

Aster

If a plant screams divide me it is because it is becoming less productive and blooming less.

If it is getting crowded out by new starts, or has a hole in the middle of the mother plant it wants to be split in two or more. Even soil gets depleted around perennials and that is a warning sign. You get those annoying weeds that you can’t remove without lifting and dividing the perennial, so dividing is inevitable. Or we just get greedy and want more of our favorite plants.

Dianthus

Dianthus

If you divide in the spring, it allows enough time for roots to settle in before hot summer weather. Spring division is best in early spring just when the growing tips of the plant have emerged. Perennials often bloom a little later than usual if spring divided.

yarrow

Yarrow

There are lists that help you know how often to divide perennials and when is the best time. You might notice that a rule of thumb is if the perennial blooms after mid June it gets divided in early spring or simpler to remember, the season opposite of when it flowers. In the coldest regions, many do all the dividing in early spring so that plants fully recover before winter sets in and the ground freezes.

In our area…

Black-eyedSusans

Rudbeckia

Here is some guidance for early spring when the soil is workable (usually in late April or May in our area) every 1-3 years.

  • Aster
  • Achillea
  • Centaurea
  • Coreopsis
  • Delphinium
  • Dendranthema x grandiflora
  • Dianthus
  • Dicentra
  • Heuchera
  • Leucanthemum
  • Monarda
  • Oenothera fruticosa
  • Penstemon
  • Phlox paniculata
  • Physotegia
  • Tanacetum
  • Tiarella
  • Tradescantia
CoreopsisBed

Coreopsis

Early Spring every 3-5 years

  • Astilbe
  • Armeria
  • Campanula
  • Gaillardia
  • Hemerocallis
  • Liatris
  • Lysamachia punctata
  • Polemonium
  • Malvia
  • Nepeta
  • Rudbeckia
  • Veronica
Veronica

Veronica

Early Spring every 5-8 years

  • Alchemilla
  • Anenome
  • Aruncus
  • Filipendula
  • Geranium
  • Heliopsis
  • Hosta
  • Iris sibirica
  • Pulmonaria
  • Thalictrum
Pulmonaria

Pulmonaria

And there are plants that are especially unhappy about being divided and best left be like Baptisia, Dicentra, Aconitum, Lupine, poppy, and Peony. Peony is best moved or divided in late September in our area. Those with long tap roots do not tolerate division well. All can be divided, but just not as reliably.

Coming up, So You Want to Change Bloom Time on Your Perennials?, and Lush gardens of June Leave Gaps in the Garden.

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About Garden Walk Garden Talk

I love to photograph, paint, draw, design, garden, travel the world, and pass on a few tips and ideas that I learned through experience as a Master Gardener and architect. I am highly trained in my field and enjoy my work each and every day. I garden in Niagara Falls, NY in zone 6-B. Find me at: http://gardenwalkgardentalk.com
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28 Responses to Divide Me Please

  1. Great list Donna…I missed my opportunity this early spring due to weather….

    • I really divide much of the year depending on what I am dividing, but as a designer, I just tell folks to stick with basic rules. Early spring works out great here though. Our group is dividing in March for our plant sale, but I pot them up in fall to overwinter.

  2. Loretta says:

    Great list, it’s definitely different in every region. Moving actual plants should be done in the Fall though right? I’m hoping to move some azalea plants, but I think I’ll wait till the cooler weather. The perennials definitely do well when they are divided, but with an urban garden, how does one take control of space? My husband is always after me that there is just too much out there, it infuriates me, I’m the gardener, he’s NOT! 🙂

    • Many shrubs and trees are better off in fall (like your azalea) but in our area, spring is a wonderful time for the perennials, yet fall is fine too. In spring, they get better rooted and can concentrate on flowering for the next year. I have moved some flowering plants in Spring that will still flower, but some the transplant shock is too great. The tree farm moves many trees in spring too, but it depends on the species. Give your divides to plant sales if you run out of room! I do.

  3. lucindalines says:

    Such good advice.

  4. M E Cheshier says:

    Great shot!

  5. M E Cheshier says:

    Reblogged this on Travels with Mary and commented:
    Great shot!

  6. You have a stunning bunch of coreopsis Donna! How long have you been growing them in that spot? Mine have never filled out like that. Plus the rabbits like to prune mine.

    • This was a previous design in my garden, not what is there now. All the coreopsis in that hedge went to neighbors. They were only there a few years in my garden. The spot is very dry. Too bad rabbits are in your garden. Here, I get one, but I have so much planted, I can share.

  7. These are wonderful reminders.

  8. A.M.B. says:

    Thank you! I’m not in your area, but this list is still helpful. I am going to be dividing my mother’s irises (she has about 1/2 acre just of irises and everything needs to be divided). I’ll be planting a good portion of them at my house. I wish peonies tolerated dividing/transplanting better, but I’m also going to be taking a row of them from my mother. She put them in a shady spot, and they almost never bloom now. I have a better spot for them.

    • A.M.B. says:

      I meant to say 1/4 acre of irises!

    • I have moved iris almost anytime, even at times not recommended. They are sturdy plants. I have moved my peonies twice already too. With peonies, they may not flower the next few years though. They really are not happy about moving. Great you are getting plants from the family. Always nice when they come from people we love.

  9. Reblogged this on Rhymes with Linnaeus and commented:
    Had to share this timely post on dividing plants by fellow blogger Donna of Garden Walk Garden Talk. She lists plants that should be divided and when, as well as plants that aren’t happy about being divided. Be sure to peruse her blog. Her posts are always thoughtful, informative and filled with great photography.

  10. Brian Comeau says:

    Are you a flower girl only or do you fix trees too? Any suggestions on trimming cedar? I have a row that have all grown at different lengths. Some tops are brown. Other issues potentially? Thanks!

    • There are good videos online you might watch, Brian. They are pretty forgiving if you mean cedar like Eastern or Western red cedar. Junipers are really trimmed hard often in gardens and I have a large tree cedar in my garden. They do get browned in winter from lack of moisture and wind, but if not diseased, will grow back nicely if not too tightly trimmed past what is green growth.

  11. debsgarden says:

    I have a few perennials, and it is always rewarding when I can divide them for more plants. Well worth the work!

  12. Excellent advice, Donna. Missed dividing my day lilies this year, though. Fortunately, the garden is pretty forgiving when I mess up. P. x

  13. I am very lazy about division, but fortunately so many of my plants, like Monardas, are incredibly easy to divide. Still, my favorites are the ones who don’t want to be divided at all, like Baptisia and Asclepias.

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