How to plant perennials

October 9, 2015

Whether your garden is a cramped backyard or a generous plot of land around a country house, there are always places to use perennials for the varied colour and character of their flowers and foliage. These simple guidelines will help you properly plant perennials so they flourish.

How to plant perennials

1. Types of perennials

The terms "perennial" and "herbaceous perennial" are often used interchangeably to mean a plant that comes up year after year and in most cases dies down to dormant roots each winter, leaving only lifeless stems.

  • The lupine, delphinium, phlox, and monarda are popular examples.
  • A few, such as the yucca and dianthus, are termed and treated as herbaceous plants even though their leaves remain green all year. Tolerance to cold depends on the species or cultivar.
  • Some perennials, such as hollyhock and delphinium, are short-lived, dying out only four or five years after planting.
  • But others, such as asters, tickseed, and anthemis, will live for many years, and will respond with renewed vigour each time you dig and divide them.
  • A few perennials, such as peony and meadow rue, will continue to thrive for decades with no special care needed.

2. Preparing the perennial border for planting

  1. Spade or rototill the bed two or three weeks prior to planting to give the soil time to settle.
  2. Remove all perennial weeds.
  3. Incorporate a bucketful of peat moss or compost per square metre (three feet square), or spread about three to eight centimetres (one to three inches) of it over the area first. Also, sprinkle a complete fertilizer (a mix of equal parts blood meal, bone meal, and kelp meal) over the area prior to spading.
  4. Apply a small handful per square metre (three feet square).Just before planting, rake the area to break up any large clumps of soil and to level the surface.

3. Setting out new perennials

Perennials can be planted almost any time the soil can be worked. Spring is the most popular season, but fall is also excellent. In cold regions spring planting is probably safer; fall planting must be done early so that plants become established before winter.

  • Apply mulch after the ground has frozen, to prevent alternate freezing and thawing, which heaves plants up out of the soil and exposes roots.
  • Container-grown plants establish themselves readily even when in bloom and can be planted in summer if they are kept well watered.
  • Dormant perennials, either bare rooted or in small pots, may arrive by mail several days before it is convenient to plant them.
  • Open the package, water if necessary, and keep in a cool place indoors or in a shaded place outdoors away from drying winds. The sooner they are planted, the better are their chances of survival.
  • Water well after planting.
  • Take care to set the plants at the proper depth. In most cases this means that the point at which roots and stems meet should be at the established soil level. If planted too shallowly, the roots will be exposed; if too deeply, the crowns can rot.
  • Space the plants to allow for the eventual spread of the foliage. The best effects are obtained when three or more of one kind of plant are set together.
  • For plants with small root systems, use a trowel to make holes; for large root systems, use a spade.
  • Make holes large enough to accommodate the spread-out roots.
  • Set the plant upright in the centre, and fill the hole with soil.
  • Firm the soil around each plant and water.

Following these tips will help ensure your perennials are planted properly.

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