How to Keep Perennials Healthy

Perennial plants are the gardener's delight as they continue giving year after year - their foliage, blooms, fruit, berries, etc., are taken as a constant. However, their constancy can turn to neglect sometimes as we take them for granted. It is important to keep them in top shape all year round, so that they produce more of what attracts us to them in the first place.


  1. Image titled Keep Perennials Healthy Step 1
    Keep them groomed. Cut away dead and decaying foliage regularly.
    • Early summer: Dead-head flowers and remove any stringy bits at the end of flowering season. Dead-heading should be done weekly or fortnightly during summer unless you are looking for seed stock. Removing flowers promotes the growth of fresh leaves and often more flowers in many species of perennials. This should be done in early summer. Perennials suited for deadheading include alchemilla, Aquilegias, nepetas, geraniums, pulmonarias and Symphytums. ([1]
    • Winter: Tidy up and cut down the plants. Use garden shears (hand or electric) or secateurs. Make sure the seed heads are finished first and tidy the plants up so that they appear neat.
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    Check their growth. From time to time, it is important to keep an eye on how they are growing, then be sure that they are conforming to growth standards set for them. If they seem to be lagging behind for a long time, you may need to take remedial action to improve their lot, such as fertilizing or shifting their location in the garden.
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    Divide them. If your perennials are up to being divided (and many of them are), this is an important means for thinning them out and moving extra growth around the garden. For most plants, this can be done wherever you feel it is appropriate, although some of the plants need this to be done regularly, as explained below. To divide perennials, simply:
    • Insert two gardening forks together into the centre of the plant, back to back and gently ease them apart.
    • Trim away any rotting, diseased or old growth from the inner part of the plant. Also remove woody parts. Select the best pieces of the plant for replanting (usually around the edges).
    • Replant the two halves - one back where it came from, and the other somewhere else in the garden.
    • Note that some perennials need regular dividing or they become scraggly and cease to thrive. Watch for heucheras, asters, monardas, sedums and stachys, which do need annual or biannual division. ([2]
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    Always use the right soil type for the perennial. This will help ensure trouble-free existence for years to come. It also means ensuring that soil top-ups or fertilizing are very important to remember and do - add this task to your gardening calendar. If a previously moist but well-drained soil suddenly becomes soggy, you may need to either fix the soil, or shift the affected perennials, or you will notice that the plants no longer cope as well and may suffer from root rot or other waterlogging damage.
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    Add compost every spring. Keep the garden space well mulched and add compost to perennials every spring to give them nutrients to draw from. It is also important to feed perennials with nutrients throughout summer.
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    Keep the insects at bay. Use eco-friendly garden sprays (see "Relateds" below for examples) on a regular basis to remove such insects as aphids, thrips, whitefly, beetles etc.


  • It is a good idea to put early bloomers behind late bloomers to hide the earlier messy growth with the later neater growth.
  • Note that in some climates that have snow for a longer part of the year, perennials are often treated as annuals. This doesn't have to be the case if you have room to bring the plants inside to over-winter but the logistics and practicalities involved often mean that gardeners simply replace these plants every year despite their potential to be perennial.
  • If you are growing perennials in pots, they will need repotting from time to time, to replenish the soil and to give them larger potting space in which to grow. This is best done in spring or autumn, when the weather is less fierce in temperature extremes.
  • Make a compost tea to help keep your perennials healthy.
  • For perennials that get waterlogged or soil-tired, take cuttings or remove seeds to plant them elsewhere in the garden. Otherwise, you will find they aren't quite so perennial!
  • Delphiniums that are cut off at the base may repeat flower. Try cutting above the bud for for Achillea, heleniums, penstemons, and salvias to get repeat flowering. ([3]
  • Don't worry about some perennials that appear to "die" over summer, such as oriental poppies, acanthus and zantedeschias - they are just going dormant to ride out the hotter weather. ([4]
  • Always keep snips, trimmers etc., sterilized in between use on different plants, to help avoid the transfer of any diseases that one plant might be harbouring.


  • Remove ant nests near garden beds, as they will tend aphids in the garden.
  • Try not to spray the ladybirds!

Things You'll Need

  • Gardening fork
  • Perennials
  • Good soil and location
  • Trimming implement for removing woody and diseased pieces

Sources and Citations

  1. New Zealand Gardener, Perennial Performers, October 2006, p 78, ISSN 0028-8136)
  2. New Zealand Gardener, Perennial Performers, October 2006, p 78, ISSN 0028-8136)
  3. New Zealand Gardener, Perennial Performers, October 2006, p 78, ISSN 0028-8136)
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Categories: Growing Flowers