Perennials Routine Care & Division

Perennials are plants that live for several years, though some are longer-lived than others.  This can vary a lot, depending on your climate, soil conditions, insects or diseases, and the plant in question.  Herbaceous is a word used to describe plants that do not develop woody stems.  Most garden perennials therefore, fall into the category of herbaceous perennials.  This is to distinguish them from trees and shrubs.

What Perennials Will Do

No matter what your garden situation, there are a number of perennials available that will adapt to the conditions you already have.  There are perennials for sun, shade, clay, sand, wet or dry soil, hot and cold climates, and everything in between.

Perennial flowers appear in every colour of the rainbow.  No matter what colour scheme you can think up, there will be a perennial available to match.

Perennials can provide you with a much broader selection of plant material to choose from when planning your landscape.  They are a good investment, not only providing you with most of the same benefits as annuals but they even come back and get bigger.


All plants are given a hardiness rating to determine the type of plant that is best suited for certain areas.  These ratings are guidelines based solely on the average minimum low temperature.  In reality though, there are many factors to consider; the average high temperature in summer, extremes of heat and cold, rainfall, humidity, soil moisture and exposure.

When considering a plant for its hardiness it is important to remember that microclimates and unusual weather patterns influence the success or failure of any given plant.


Because perennials are permanent, they require a deep foundation with proper drainage.  Well rotted manure, bone meal, compost, peat moss can all be incorporated into the soil.  Ideal perennial beds are mounded up above the rest of the soil level so they drain properly.  This will eliminate the chance of root rot caused by spring thawing or overwatering.


On the prairies, Mother Nature usually does not provide the required amounts of moisture needed to maintain a flowerbed throughout the summer.  Monitor your beds often and apply generous amounts of water when required to encourage deep rooting.  This will make your plants more resistant to drought and cold.  Reduce amounts of moisture in August so plants will harden off, slow down and prepare for winter. 


Regular feeding with 11 12 6 or 20 20 20 fertilizer through the growing season will provide you with steady growth, maximum blooming and a longer plant life.  Avoid fertilizing past the end of July.  This, in conjunction with reduced watering will prepare the plants for the fall and ready them for the cold months ahead.


Apply a layer of mulch on the ground around your plants.  This will help to conserve moisture, prevent erosion, retard weed growth, moderate temperatures and keep the surface from crusting and packing.  Materials to use are shredded bark, peat moss, sawdust or similar products.  It depends primarily on what is available.

Shredded bark is the most popular because of its appeal and neatness.  Mulching may be costly a first, but when you consider the benefits, especially the lack of weeds and reduced watering it makes good sense.

Winter Protection

The survival of perennials improves greatly when they go into winter moist, dormant and protected with a covering of mulch.  After the tops have been killed or heavily damaged by frosts, cut down to 4 to 6 inches from the base.  The tops may be used in conjunction with shredded leaves, bark, and peat moss as a covering for the plant.  The application of evergreen boughs may be used after the Christmas holidays for added protection against warm, sunny winter days.

Dividing Perennials

  • to rejuvenate plants 
  • increase the quantity (propagation)
  • maintains health and vigour
  • improves flower production
  • spring is the best time for most 
  • divide spring flowering plants after they have finished flowering
  • divide when foliage is taller than 5cm(2") but less than 10cm (4")
  • Peonies should be divided and moved in September
  • start by watering plants to be divided
  • cut back top growth of plants prior to dividing to reduce stress
  • early morning or evening is best time, avoid hot, sunny days
  • dig up clump with as much soil as  possible and separate the young offshoots from the large woody center
  • discard central woody stem, replant new plants (divisions) at the same depth immediately and water thoroughly 
Large Perennials: use a spade to split up the clumps—each clump should have at least three stems and lots of roots 
Small Perennials: use a sharp knife to cut clump into pieces ensuring that each piece has at least one growing point and some roots

**** Do some research prior to dividing to make sure plant can be divided—some plants have deep taproots and should be left alone!