What do gardeners want? The simple answer is to see beautiful blooms every day of the growing season. What we’re more likely to see are a few bursts of colourful blossoms interspersed with increasingly long periods of green leaves. This scenario is the result of planting only what interests us most (or what recently seduced us at the garden centre), instead of following a design plan that brings consistent bloom from spring through summer and into autumn. Now, Garden Making is providing garden design ideas for all season blooms by creating a perennial bed with non-stop flowers from spring right through to fall. We list the plants that will feature each season and provide a diagram for the planting plan.
Length of bloom for perennials
For many years, my garden produced an impressive display of spring bulbs and early-flowering shrubs like forsythia and lilac, followed by flushes of bloom from peonies and roses. A few hydrangeas and daylilies came on in midsummer, but then there was a long slide into green gaps lasting for several weeks, until the fall leaf colours appeared in trees and shrubs. Basically, the garden offered impressive floral displays for a few brief weeks, interspersed with periods of no flowers at all. The bloom sequences were unreliable, and I couldn’t expect to see the garden in bloom for the full growing season. This was disappointing and, at the very least, limited my opportunities for garden parties.
Looking beyond the seductive categories of lilacs, roses, peonies and irises to less familiar families like penstemons, yarrows, monkshood and snakeroots led to expanded periods of bloom in my large perennial bed, and the beginning of a constant bloom strategy. Using a calendar to pinpoint the green weeks with no visible flowers, I filled in the gaps with plants scheduled to bloom in these empty periods. After two growing seasons, there were increasingly extended periods of blossom. Learning about perennials beyond my initial list of favourites, and then planning and planting for timed flower sequences through three seasons brought me closer to the goal of a garden in bloom every day from spring through autumn.
Informed selection in plants for your border and practical maintenance considerations go a long way toward keeping a garden in bloom. The average length of bloom for perennials is three weeks, but some, like summer phlox, stonecrops, catmint and columbines, will bloom for six to eight weeks, providing convenient overlaps from one season to the next. Others, such as several dwarf daylilies, will even be in generous flower from late spring through frost. Although clumps of perennials acquire drought hardiness as they mature, their ability to produce flowers for extended periods is greatly enhanced by fertilizing in spring, watering weekly and deadheading spent blooms.
Number of plants to use
With a time sequence design in hand and a willingness to acquire multiples of new plants (and really, how hard is that?), the next decision is how many plants are required to fill in the weeks when no flowers are on display. This is a matter of perception: you may be satisfied with fewer, while others may need more to feel that the bed is in bloom every week of the growing season. Whether you’re cautiously conservative or extravagantly enthusiastic, it’s possible to make a garden bed that will continuously bloom for three seasons.
The perception of fullness is based less on the number of plants in bloom and more on the colour and texture contrasts among the plants that are in flower at the same time — for example, the variegated silver-and-green leaves of ‘Excalibur’ lungwort contrasted with the purple foliage of Roses weigela. Also, if a particular plant, like the lungwort, is known to make a robust spring display, it would be smart to capitalize its energy and put three together for a big burst of colourful flowers and foliage, and a second group of the same plant at the other end of the bed. The repetition of such a high-performance plant adds eye-catching fullness to the bed, and is the keystone plant to combine with at least two other perennials that bloom at the same time. Three different plant varieties placed strategically would produce a sense of fullness even with fewer specimens — and the bed would be in bloom.
To my eye, three different plants blooming together is the minimum, and you might wish to expand to five or six selections that all bloom at the same time. As discussed, some of those could be high performers, and therefore good candidates for repetition, to be used in a couple of locations. Your justifiable greed for plants will most certainly be rewarded with an increased sequence of bloom and fewer weeks of just green.
Having come this far with making a shopping list and a planting scheme to fill in green periods, it bears mentioning that woody plants are an asset in the perennial bed, providing structure and their own blooming sequence in the master plan. Shrubs will contribute their flowers, and may have purple or variegated foliage. Trees and conifers bred for narrow stature can contribute flowers and ornamental fruit, as well as winter interest. When selecting woody plants for a perennial bed, just be sure their width at maturity won’t crowd out other valuable specimens.
The planting plan and plant list
The garden bed design in this plan is intended to show perennial plants transitioning in and out of bloom through three seasons. The plan is structured with six perennials and a woody specimen for each season (you could use fewer, still with good results). Factoring in additional overlapping bloom from high-performance plants, it’s going to be a year of abundant flowers and more than one garden party.