Back to blog

Perennials proper maintenance: cut, divide and fertilize

The huge popularity of perennials stems from their ability to surprise and delight: hidden and somewhat forgotten through the long months of winter, they emerge in the spring with a brilliance that energizes gardens and landscaping everywhere. Most perennials are not very demanding when it comes to maintenance, but some basic care is required.


When the warmer weather arrives, it's time to commit to a good spring cleaning.

  • Pinch plants back (for tighter, compact plants) before new stems appear;
  • Clean out dead leaves and pull weeds;
  • Remove all dead and damaged parts from plants;
  • Incorporate compost;
  • Plant new varieties.

Growing season

Unlike annuals, perennials do not bloom throughout the season. You can simplify your maintenance program by grouping your perennials together according to soil type and fertilizers required.


Deadheading refers to removing flowers once they've faded. This is an important step in maintenance since it helps preserve a plant's vigour by preventing it from directing its growth towards seed production. Bellflowers, Delphinia, Baby's Breath, Dianthus, Gaillardia, Phlox and Yarrow will all produce new flowers if they are deadheaded promptly and regularly. You can prolong flowering periods and, by extension, your enjoyment!

  • Phlox, Bellflowers: cut flowering stalks or individual flowers with snips just above a leaf or secondary twig.
  • Astilbe, Daylily, Hosta: cut as close as possible to the base of the inflorescent stalk.
  • Penny-cress, Moss Pink and ground covers: use scissors to cut flower stems as close as possible to foliage.


Summer is the period of optimum growth for perennials. Although pruning may not be necessary, a few judicious cuts can help to:

  • Control the size of the plant;
  • Reduce the risk of illness;
  • Create shapes and texture in your flower beds;
  • Redirect growth.


Most perennials benefit from being divided every few years. More often than that, you risk impacting blooms and growth negatively. Remember that each time you divide or move perennials, maturity is delayed by one year. The best time to divide a perennial will depend on its flowering period.

  • Spring flowering: divide when blooming has come to an end, generally between late-May and mid-June.
  • Midsummer to autumn flowering: divide in April or May, when plants have started to grow.

How to divide a plant:

  1. Loosen roots and isolate the clump;
  2. Lift the root ball with a spade;
  3. Dig the plant out of the ground and try to maintain the root system as intact a you can;
  4. Divide roots with a knife or the edge of the spade so that each part contains roots and stems;
  5. Separate by hand, shake out any excess soil and remove weeds;
  6. Replant promptly so roots don't dry out, one section at a time;
  7. Water well and cover the soil with mulch.


Established plants do well with time-release nourishment, such as compost and granulated fertilizer.

  • Use fast-acting liquid fertilizer for mid-season remedial fertilizing of fading plants.
  • Stop fertilizing by mid-July.

Give "fussy" plants fresh compost or fertilizer on an annual basis, and fertilize more "independent" plants every few years.

Avoid nitrogen-rich fertilizer. A high-nitrogen mix will promote foliage over flowering, and it will increase your plants'susceptibility to cold, insects and disease.


Perennials with heavy flower heads or long fragile stalks need some sort of support:

  • Install stakes early in the season; then
  • Secure your plants to them as they grow.

Bushy thickets like Peonies can be supported by metal hoops of various diameters at the appropriate height.

Perennials that are particularly tall or produce long floral spikes,such as Lilies or Hollyhock, can be staked individually.

  • Place bamboo poles in the ground behind them;
  • Tie them with a rope at 30 cm. intervals

Another option

You can also stake your medium-tall plants with twigs cut from heavily-branching trees, placed in the ground near the root ball. This is a natural-looking option and especially recommended for geraniums. You don't want the stakes to upstage the plants, however, so they should be three-quarters as long as the fully-grown plant is tall.

Fall: time to plant and protect



Although it is possible to plant perennials all season long, fall planting offers several advantages. Plants will take root before winter sets in, making them more resilient in periods of drought. And, you'll be able to enjoy the early flowering plants the very next spring!

  • Clear where you intend to plant;
  • Dig to a depth of approximately 15 cm;
  • Till the soil;
  • Soak the roots before planting;
  • Perennials will harden off after the first frost, which is the ideal time to install winter protection;
  • Leave stems to protect your plants and trap snow in winter;
  • Place dead leaves around your plants, which will provide natural insulation and nourish the soil.