Many gardening books emphasize the importance of dividing your perennials according to a specific schedule. For each variety described, they inevitably recommend dividing every three, four, or five years. There are no exceptions.
Divide as Needed
I’ve always wondered why people are so obsessed with dividing plants. After all, in nature, no one divides plants, and they still manage to survive. So why should I do it just when they’re starting to look their best? Because it takes most perennials three or four years to reach their peak flowering stage.
Personally, I don’t divide my perennials on a predetermined schedule; I divide them as needed. If they spread so much that they encroach on their neighbors, I divide them. If their flowering decreases and I suspect it’s because they’ve become too dense, I divide them. If they become hollow in the center, I divide them. If I need more plants for a new bed, I divide them. But as long as they are beautiful, productive, flowering, and not bothering their neighbors, I let them grow as they please. As a result, I very rarely divide the vast majority of my perennials, and most of them are never divided.
For me, dividing is really a case-by-case decision. Some astilbes and daylilies start to flower less after four or five years, and then, yes, it’s time to divide them. But others are still magnificent after 20 years without any care whatsoever! So I leave them alone!
Slow-Growing Perennials
Dividing only when necessary makes even more sense when the plant is slow-growing. When I come across a book that suggests dividing my hostas and peonies every five years (take a close look: most of them insist!), I can’t believe it. These plants grow at the speed of a snail with anemia: it takes at least ten years for them to reach their peak… and even after ten years, the less you divide them, the more beautiful they are. You see gorgeous hostas and peonies that are 50 years old and older: they are much prettier than the scrawny specimens divided every five years.
(I suspect that authors who encourage such excessive maintenance have a slightly Calvinist streak in their nature, believing that only through hard work can one find heaven. I, on the other hand, experience heaven on earth thanks to my flower-filled beds that require so little attention!)
Exceptions
Of course, there are exceptions to every rule. There are some short-lived perennials, such as gaillardia, flax (Linum perenne, for example) and several coreopsis, which should logically be divided every two or three years, otherwise they will disappear without warning. But it is much easier to take cuttings than to divide the plant. Cut a leafy stem, remove any buds or flowers, and root it in moist potting soil: it’s so easy and doesn’t reduce the flowering of the mother plant as division does. There are other short-lived perennials that are best left to reseed, as they hate being divided and do not take well to propagation: lupins, columbines, lychnis, etc.
Suggestion from a laidback gardener: make your life easier and only divide perennials if you have a good reason to do so!
This text was first published on this blog on May 11, 2015. It has been revised and its layout has been adapted.
Exactly! I do happen to divide many perennials very regularly, but only because I propagate them for large areas.
with ref to crushed egg shells to improve Lavendar growth & better flowers Ive a quicker solution .I use finely crushed oystershell grit ,after applying for a month About a handfull per plant the responce is amazing,its sold for birds & chickens ,hope members find this helpful ,Patrick
This article is helpful. I find I have to cut back (and share), as opposed to divide, our daisies and hosta every year, as they spread so much. I wondered why some of my gaillardia disappeared from time to time. I shall keep a closer eye on them with a view to catching them to propagate before they make a no-show.
Ha, as I re-read, I guess I am dividing, but often it is just removing outside plants not formally cutting in half or thirds, etc.