Perennial plant care

Spent flowers on perennial plants should be removed, or deadheaded, to encourage flower production



Perennial flower


Perennial plant maintenance

Routine feeding and watering will generally be enough to satisfy the nutritional needs of perennial plants through their growing season. Spent flowers on perennial plants should be removed, or deadheaded, to encourage flower production. Perennials may be pruned back and mulched for extra protection in the fall. This mulch should be removed in the spring. If you do not wish to mulch, leave foliage on plants, as leaves will collect snow for insulation and moisture during the winter. Dead foliage should be pruned away in the spring.



Dividing Perennial plants

If the flower quality and quantity drops in your mature perennials, this may be a sign of overcrowding and they may need dividing. Some may simply have outgrown the place they are in or other plants, as they grow, may be creating too much shade for sun loving perennials. Many perennials form clumps of stems. These stems are actually individual plants with their own root systems. Some perennials cannot be divided if they grow from one central stalk. Early blooming perennials should be divided in early fall. When all the leaves have fallen, gently dig up the plant and separate the roots of the individual clumps to be removed. Replant the removed plants in an appropriate place in the garden. Later flowering perennials should be divided in the same way in the spring, as soon as they are showing growth.

One of the greatest things about plants is their innate ability to recover from damage and that's why it's perfectly ok to divide your perennials. In fact, most perennials benefit from being divided. Doing so can keep them healthy, vibrant, and contained in their place at the same time providing you with good quality plants for other places in your garden. Late summer is the perfect time to do it as the temperatures are a bit cooler. Try to avoid dividing perennials during the heat of the day; early morning or evening is ideal.

There are many reasons to divide your perennials; more plants are just one of the reasons. Some perennials grow very quickly forming large clumps. These clumps can begin to die through the centers every few years or so. This leaves bare spots in the middle and the plant itself looking lackluster and tired. As your perennials grow over the seasons, they also tend to grow into each other creating competition that just didn't exist when you planted them. This tends to lead to smaller plants and flowers. This goes especially for vigorous growing plants like the Obedient plant which can overwhelm their neighbours in just a couple of seasons. Dividing your perennials circumvents these issues and leaves you with perfectly good plants to use elsewhere in your garden or share with friends and family.

Dividing your perennials is a rather simple process and it ensures your perennials will grow better in the years to come. First, determine which perennials you are going to divide. Plants that are not fully flourishing, are bare in the center, produce fewer flowers, or are crowding borders or other plants are good candidates. Water these plants thoroughly a day or two in advance of the dividing process as it will help by softening the soil so when you divide its easier on you and the plant itself. Here are all of the ins and outs of dividing your perennials so they last for years to come.

Use a garden fork or shovel to dig down on the outside of the root-ball and lever the plant loose from the soil. Once the plant has been loosened, try to center the root ball on the tool and gently lift the plant from the soil. You especially want to take care that you lift as much as of the root as possible without tearing up the root system. Try to leave it in a ball. Once the plant has been uprooted gingerly, shake the excess dirt from the roots and wash them clean with water. This will make it easier for you to divide the clump.

You will see the plant has individual crowns that form the clump. Divide the plants at the crowns by cutting or hand prying them apart. Each crown will need to have roots and leaves in order to survive the process. The amount that you divide the plant is up to you and the space requirements you have, but try not to divide it into too many small pieces. Promptly replant the divisions before there is any chance that the roots may dry out. You may want to have some areas ready to plant ahead of time. Plant the divisions at the same depth as they were when you dug up the perennial. At this point, you could also fertilize with bone meal, or give it the best chance possible with a mycorrhizae beneficial fungus like Myke, then water in well. If it's super dry, then you should also cover the freshly planted root area with mulch to retain moisture until your plants establish themselves. If you are saving plants for friends, move the plants to a shady area and keep the roots moist with a damp cloth or paper towel; keep the roots moist until you make the hand-off.

Perennials like Bearded Iris grow from rhizomes which are much like bulbs. You can tell a rhizome by a fleshy stem that grows along the ground. Now is the very best time to divide rhizomes as these plants are resting during this period of late summer. Carefully dig out the rhizomes with a shovel or trowel and then wash off the excess soil to expose the shoots. Each viable rhizome will have roots growing out the bottom and a set of fan leaves at the base of the shoot. Cutting the foliage back by 2/3 will help prevent moisture loss and focus more of the plant's energy on root development. If your rhizomes have grown together very closely or if your plants have become very mature, you can also divide the rhizome. Your divided rhizomes should have both roots and fan leaves. You can split them by breaking or cutting them. Replant them in a sunny spot with excellent drainage and as before use bone meal at the bottom of the hole, or use Myke directly on the roots, and water in well. You may also want to treat your rhizomes with a fungicide to stop mould or other diseases.



While most perennials benefit from being divided every few years, there are a few that don't.



Avoid dividing these varieties:

  • Balloon flowers (Platycodon)
  • Baptisia
  • Bleeding heart (Dicentra)
  • Butterfly weed (Asclepias)
  • Christmas rose (Helleborus)
  • Cushion spurge (Euphorbia polychrome)
  • Gas plant (Dictamnus)
  • Lavender (Lavandula)
  • Oriental poppy (Papaver orientale)


If you are in doubt, these perennial varieties should be divided every 3-4 years:

  • Astilbe
  • Bee balm (Monarda)
  • Black-eyed Susan (Rudbeckia)
  • Daylily (Hemerocallis)
  • Hosta
  • Peony (Paeonia)
  • Phlox
  • Purple coneflower (Echinacea)
  • Siberian iris (Iris sibirica)


If you're not sure if you should divide your perennials, just stop in at greengate. We will be able to help you identify whether or not a plant can be divided. So get out there and make some new beds for your beloved perennials and they will live on happily ever after. Happy gardening!

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