Leave flower for last when designing with perennials

Four-step design
Perennial realities
Non-plant focal points

 

Designing with perennials begins with plant form and texture, then considers leaf color and finally, takes into account which plants will be blooming, when.

This is sensible for perennials since each is in flower for only 2 to 4 weeks. We can extend bloom time for some by removing spent flowers -- deadheading -- but it's smarter to rely on the plant's non-flowering qualities to carry the load.

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Classic combination: Form first, then bloom

Here's how-to, using four plants which combine well because between them they have a variety of features that provide favorable contrasts:

  • One is large, coarse textured and mounded (peony);
  • Another is a fine mound of medium height (sea lavender);
  • The third is columnar, coarse and gray (mullein);
  • The fourth has a spreading shape, rises above all the others, is medium in texture, and has gray-green foliage (butterfly bush).

All are long-blooming, do so at varied times of year or offer multiple seasons of interest. So even when none of the four is blooming, there's visual interest in the garden through contrast in shapes, textures and foliage colors.

In love with flowers? To this solid combination we might add one or two plants that are glorious in bloom but a bit shabby afterward -- daffodils or columbine (Aquilegia) come to mind. When the initial group exhibits good form, texture and foliage color it can make up for other plants' slack time.

 

To begin: Our large coarse mound, a peony (Paeonia hybrid)

Few plants take charge in a garden like peonies do.

The bloom season may be short, but if the peony can resist its species' leaf diseases its neat mounded form and substantial foliage can act as companion, backdrop to other plants all summer.

The bloom season may be short, but if the peony can resist its species' leaf diseases its neat mounded form and substantial foliage can act as companion, backdrop to other plants all summer.

If it's a variety that can develop nice fall color that makes for a grand finale.

If it's a variety that can develop nice fall color that makes for a grand finale.

Many of the hybrids between tree peony and herbaceous peony fit the bill. These intersectional hybrids (such as the 'Itoh' types) have great bloom, healthy clean foliage, and at least a fair record of significant fall color. In more traditional peonies, we keep a look-out for the rare varieties that provide all three features. One is a late blooming single white flowered 'Krinkled White;' it can be a showy yellow in autumn. Another is an early double pink, 'Estafette,' which can develop burgundy tones in fall.

"Coarse" and "fine" describe the pattern that light creates on the plant surface. Plants with substantial leaves or crisply variegated edges tend to be visually segmented into large blocks because of the leaf edges and the leaves' bold shadows. Plants with smaller leaves or ferny small parts have less pattern, and so look more solid. Below, from most coarse on the left to finest on the right. (Read it: Lenten rose/ Helleborus offers a further lesson in texture.)

Acanthus (bear's breeches)

Acanthus (bear's breeches)

hardy Hibiscus

hardy Hibiscus

ornamental Salvia nemerosa

ornamental Salvia nemerosa

willow leaf Amsonia

willow leaf Amsonia

Next, a fine mound: Sea lavender (Limonium latifolium)

Its foliage is large, but entirely basal so it's completely hidden from bloom time until fall by flowering stems which create a dense, fine dome. This is a relative of statice, described in bloom as "a lilac-pink baby's breath." We often pair it with a coarse foliage plant such as peony, or something of a different shape such as columnar gayfeather (Liatris spicata).

The leaves (arrow) are basal -- at ground level only.

The leaves (arrow) are basal -- at ground level only.

In bloom, and until the spent flowering stalks are cut away, the foliage is hidden.

In bloom, and until the spent flowering stalks are cut away, the foliage is hidden.

Sea lavender is such a dependably mounded form that we're confident of it in any combination with a columnar plant such as Liatris.

Sea lavender is such a dependably mounded form that we're confident of it in any combination with a columnar plant such as Liatris.

If several plants offer equally good form and texture, we can look at how they fulfill additional objectives and choose the plant that offers the most. For instance, sea lavender is not only fine and neatly mounded from bloom time until fall, it is low care because it's neat into fall as its lilac-colored bracts remain intact even in seed

If several plants offer equally good form and texture, we can look at how they fulfill additional objectives and choose the plant that offers the most. For instance, sea lavender is not only fine and neatly mounded from bloom time until fall, it is low care because it's neat into fall as its lilac-colored bracts remain intact even in seed

It is also attractive to beneficial insects. Its abundant nectar satisfies the likes of cricket catcher wasps.

It is also attractive to beneficial insects. Its abundant nectar satisfies the likes of cricket catcher wasps.

Third, ornamental mullein (Verbascum hybrids) for gray green verticality

Ornamental mulleins are underused. They're great for sunny dry places and foliage effect. We add their gray-green large leaves to this group for contrast. The spike form flowers are an additional accent, but only for a few weeks. 

With perennials, it's best to accept the reality of spent blooms. Either look the other way as they go brown, or step in and clip them off in time to promote a second flush of flower.

 

Finally, height and spread: Butterfly bush(Buddleia davidii selections)

A dwarf such as Buddleia 'Nanho' is the right size (5' rather than its species 6-10') for most perennial combinations. There are even smaller selections, such as the 36-inch 'Lo and Behold' series in blue-violet, lilac, white and purple, and the 'Flutterby Petite' series that includes the best blue we've seen in 'Blue Heaven.' When we add the gray green spreading arms of butterfly bush to a peony-mullein-sea lavender combo, we seal the deal on drama right through summer. There will always be a pleasing contrast between one or more of the plants. As a bonus, the butterfly bush brings bloom and the delightful presence of butterflies and hummingbirds in late summer.

Varieties such as 48-inch, apricot-flowered 'Clementine' can be kept blooming longer than others, if spent flowers are removed. Another long bloomer is a 12-inch dwarf hybrid 'Blue Pixie.'

Varieties such as 48-inch, apricot-flowered 'Clementine' can be kept blooming longer than others, if spent flowers are removed. Another long bloomer is a 12-inch dwarf hybrid 'Blue Pixie.'

Butterfly bush in bloom is colorful for many weeks in late summer and fall. However, a main player in a perennial design should be an addition to the garden even before its bloom time.

Butterfly bush in bloom is colorful for many weeks in late summer and fall. However, a main player in a perennial design should be an addition to the garden even before its bloom time.

Even before bloom, it can be deliberately placed as a contrast in height and foliage color. (More of this translation of living plant to basic-feature caricature in the perennials list Great Perennial Combinations.)

Even before bloom, it can be deliberately placed as a contrast in height and foliage color. (More of this translation of living plant to basic-feature caricature in the perennials list Great Perennial Combinations.)

 

Add it up, see the perennials live up to the plan

It's not bloom that carries this design where lenten rose (Helleborus), blooms in April and butterfly bush (Buddleia) blooms with Clematis viticella in August.

It's not bloom that carries this design where lenten rose (Helleborus), blooms in April and butterfly bush (Buddleia) blooms with Clematis viticella in August.

Consistent good looks come from the contrast in foliage colors and textures and plant forms and heights.

Consistent good looks come from the contrast in foliage colors and textures and plant forms and heights.

Some other plants in this bed: Boxwood 'Winter Gem', variegated Liriope, lungwort (Pulmonaria), false indigo(Baptisia australis), oakleaf Hydrangea (H. quercifolia), big betony (Stachys micrantha).

Accept perennial realities:

Deadhead or cut back if brown isn't your color

Flower is fleeting even on the longest-blooming perennial such as threadleaf coreopsis. Even if a plant's in flower for six weeks, it must occupy its space pre- and post bloom for 3 or 4 times as long each year.

So if we rely on flower or use plants with big blooms that age to big brown, cutting is important. Fortunately, it's simple to do. Look for brown, cut it down!

Examples: Blanket flower (Gaillardia) and big betony (Stachys micrantha).

One last trick: Use non-plant focal points

It's tough to maintain a single focal point in a garden full of constantly changing plants. Yet gardens need that kind of direction to keep the eye happy. We often position a bird bath, bench, arbor or path among the plants as a focal point.

Take a look here as we use a path as a focal point, framing it with non-plant features (tree trunk sculpture and bench).

The meters and emergency generator are not pretty but neither can they be eliminated as we work out a pretty way to take the gardens around this corner.

The meters and emergency generator are not pretty but neither can they be eliminated as we work out a pretty way to take the gardens around this corner.

Look for the line we draw by extending a bed edge and creating a path.

Look for the line we draw by extending a bed edge and creating a path.

That line's meant to swing the eye along a track that will draw attention away from those eyesores.

That line's meant to swing the eye along a track that will draw attention away from those eyesores.

We add vertical interest to the left that will age to match the vertical spruce trunks on the right of the path. Like bookends tending the books between, they keep the eye centered on the path between them. A bench made of the same material helps with the bookend effect until the wood weathers gray, and gives the eye a place to stop on the far side of the path, the uncluttered side.

We add vertical interest to the left that will age to match the vertical spruce trunks on the right of the path. Like bookends tending the books between, they keep the eye centered on the path between them. A bench made of the same material helps with the bookend effect until the wood weathers gray, and gives the eye a place to stop on the far side of the path, the uncluttered side.

Another non-plant focal point of the same material...

Another non-plant focal point of the same material...

...after aging for two years.

...after aging for two years.

King Creek Timber Products in Linden, Michigan harvests these gall-affected spruces and cedars as complete trunks, strips the bark and seasons the wood like fine lumber. Homestead Timbers in Mame, Michigan has whole tree logs, too.

Metal sculpting studios such as Bad Axe Ironworks in Bad Axe, Michigan and Altra Design in Huntington, Indiana make the tree-like trellises you see here.

Metal sculpting studios such as Bad Axe Ironworks in Bad Axe, Michigan and Altra Design in Huntington, Indiana make the tree-like trellises you see here.

Related links

  • Grow 146: Continuous color perennials, lawn aeration
  • Grow 582: Renovate & redesign perennial beds
  • Columbine Aquilegia species