I've already talked about the cost savings of perennials compared to annuals.
One of the best things about perennials is that they can be divided into many more plants. Whether you are increasing the number of plants from one of your favorite perennials, or sharing plants with a friend, dividing perennials is an easy way to save a lot of money in the flower border.
Dividing your perennials also boosts the health of your plants. Many perennials eventually become crowded and may stop blooming. Some perennials like peonies almost never need divided. Others, like iris, insist on regular divisions. Dividing your perennials every few years, especially if you throw in some compost when replanting, will encourage your plants to thrive.
The best time to divide perennials are in spring or fall. Dividing plants in the heat of summer is possible but will stress the plant.
I generally choose to divide perennials in the spring when they are first emerging. Dividing smaller plants is easier and we usually receive adequate rainfall. I took all the photos in this post back in the spring one day when several friends came over for a perennial swap.
Fall can be a good time to divide perennials as well. Last night I moved some perennials around my beds. I had been waiting for some rain. We had a brief rainfall over the weekend. It didn't do much more then settle the dust, but we don't seem to be getting any great amounts this year. I didn't want to wait much longer because the plants need time to settle and root before winter. I will just need to be more consistent in watering the moved plants if we don't get more rain.
Fall is a good time to evaluate what did and did not work this year - and do something about it! In the spring I tend to be far too optimistic. I forget about the plant that flopped over on it's neighbor, or bloomed for three brief days, or lost it's leaves to sun-scalded. Now, with a realistic memory of plant performance, is the best time for me to make decisions in my flower bed.
Sometimes I walk around with a piece of paper and jot down the plants I want to move next spring. If I can remember where I've put the paper, I have a record of what to move in the spring.
When I worked at a greenhouse before I married, I always had to hide a smirk when someone came in wanting to buy "all perennials so that I don't have to do any work in the flower bed after this year." I hope it worked for them. I do think perennials are less work than annuals since (in theory) they only need planted once and need watered far less often than annuals. But even when I carefully plan a flower bed before planting, I can always see ways to improve it.
I've been known to carry a bloom around looking for the perfect companion plant to grow beside it. I don't know much about garden design but I'm slowly learning what plant combination appeal to me.
And I would hate to not have an excuse to dig in the dirt, so it is really okay with me that my flower bed is a work in progress!
But, to be practical, here is how to divide a perennial.
When you look down at the ground, on many perennials, you'll notice many stems. In the case of this coreopsis, each of these stems go down to their own roots.
I pulled apart the stems, pushed in my shovel, and separated one section of the plant.
Next I dug on the opposite side.
Now I have a new plant to move elsewhere.
The mother plant will quickly grow to her original size.
Some plants send out side shoots that are very easy to dig out - like this garden phlox.
Some plants have more woody stems and need more careful division.
I dug up this entire aster plant and carefully cut the roots in several sections with a sharp knife.
I now have three plants to replant.
The only plants I wouldn't try to divide are more shrubby perennials like butterfly bush, lavender, or caryopeteris.
Hope this makes sense to you. Happy Digging!