Garden Plants for the Overlooked Fourth Season

Perennials in the Garden for Fall and Winter Interest

Looking for ideas on how to design an attractive garden for the overlooked winter season usually means wading through lists of trees and shrubs for the most attractive fall foliage colour and winter form.  With a little luck, there might even be a few days of colourful berries to peak interest before birds or cold temperatures change the view.  After a few minutes the  lists become quite monotonous with two key plants; winterberry holly and red twig dogwood.  When many gardeners are faced with staring out the window for what could be months at the frozen landscape, it is important to broaden our list of winter interest landscape plants.

Snowy winter scene

Snowy winter scene in upstate New York

There are many more plants that can add interest to the picture than Ilex and Cornus.  Very little attention is paid to the plants at our feet. This group of overlooked plants are the perennials. Perennials can offer very interesting effects during the fall and winter as a result of their attractive seedheads. Some perennials have strong semi-woody stems that will stay upright through the entire winter, while others will give a good display through the fall and early winter before rain, wind and snow cause them to lean with casual artistry.

The showiest feature perennials offer through the snowy winter months is attractive seedheads. Wind blowing the tall stems of Eupatorium maculatum (Joe-Pye Weed) will make them sway like a living curtain. Another reason for leaving perennials standing in the fall is to see the contrast between the dark colours of many plant stems and the light colours of falling leaves and snow. The dark, woody seedpods of Iris sibirica (Siberian Iris) are very interesting when the three sectional capsule is surrounded by yellow birch leaves that have fallen around the clump. Leaving perennial seedheads intact after their flowers have finished blooming also is a benefit to wildlife. Echinacea purpurea (Purple Coneflower) is excellent for attracting finches and sparrows to the garden that are looking for food. An additional ornamental benefit to leaving perennials unpruned once they have finished blooming is that many have attractive seedheads that can be dried for fall or winter bouquets.

The following perennials are recommended because they have attractive properties in the fall and winter.

Acanthus spinosus (Spiny Bear’s Breeches) remains attractive long after the mauve-white flowers have fallen. The seedheads have the same nodding shape of the flowers. They are held high above the foliage and remain quite attractive into the fall. The spiny foliage may even remain semi-evergreen through the winter if they are in a mild enough location (with snow cover).

Many of the Achillea (Yarrow) have attractive upright, sturdy seedheads that look effective during the beginning of the winter. Since the fall is a time that Achillea often reblooms, many flowers are smaller and stems are not as sturdy as earlier in the season. Still some cultivars are excellent for fall and winter interest. Liatris spicata (Spike Gayfeather) also has attractive seedheads. Liatris has a fluffy, brown upright spiky structure that has good holding power into the winter.

Yaupon holly after a February ice storm

Yaupon holly after a February ice storm

The best time for Alchemilla mollis (Lady’s Mantle) seed displays is just after blooming early in the summer. Heavy rains during the late summer and fall will often cause the weak seedheads to lie horizontally. This in itself can be attractive in the winter as the tan star-shaped seeds are held above the leaves. One of the potential disadvantages of leaving the seedheads on these plants is that Lady’s Mantle will self-seed extensively the following year. Coreopsis verticillata (Threadleaf Coreopsis) also has attractive seeds and will also self-seed if they are left on the plant over winter. This is a small price to pay for an attractive winter display.

The pink blooms of Anemone hybrida (Japanese Anemone) seem to be everywhere lately. So many new and improved cultivars are finding their way to the garden centres that they are finding their way to many gardens. Japanese anemones are excellent for late season blooms (almost until the frost!). Some of the early blooms may even progress into seed heads that open to reveal attractive white cottony seeds.

Angelica is an interesting plant. The most commonly grown ornamental species is Angelica gigas. If this plant is allowed to flower and set seeds it will die and act like a biennial. If the plant is allowed to flower and the seeds removed before they mature, the plant acts like a short-lived perennial. If the plant is grown as a biennial, some of the seeds may germinate and start to grow the following year. If it is left to set seed, the resulting form is a very dramatic. It resembles a tall umbrella-like structure that could reach 2 metres in height.

Some perennials will actually live through the winter better if they are not pruned in the fall. Artemisia (Silver Sage) and Filipendula (Queen of the Prairie, Meadowsweet)
are two of these plants. Do not prune these plants in the fall. Leave them through the winter and clean them up in the spring. Some of the taller blooming cultivars may “recline” during the winter but this is a small price to pay for increasing plant survivability.

 Asclepias tuberosa (Butterfly Weed) has orange blooms that progress to small milkweed-shaped seedpods late in the summer and fall. These split open in the fall to release silky topped seeds. If seed-collecting admirers can be encouraged to leave the pods, these plants are quite attractive. This might be a lost cause since so many want this plant for their garden.

Salvia left unpruned in the fall has a better chance of survival through the winter and the seedheads add winter interest.

Salvia left unpruned in the fall has a better chance of survival through the winter and the seedheads add winter interest.

 

Fall and asters go together like tulips and spring. One plant that is an exceptional introduction is Aster frikartii ‘Monch’ (Monch’s Frikart Aster). This is a shorter, earlier aster that has very little trouble with pests and diseases. Leaving the seedheads standing makes sense for several reasons. Chief among these reasons are for winter architectural effect, for feeding the birds and to increase its winter survivability. A white flowering aster-like plant called Boltonia asteroides ‘Snowbank’ (Bolton’s Aster) and the tall, yellow blooms of Patrinia scabiosifolia can also be treated this way.

Many astilbe including Astilbe arendsii have attractive plume-like seed structures that create an excellent vertical accent effect through the winter. These plants also fare better if the foliage and seedhead is not pruned in the fall. Chelone lyonii (Turtlehead) is also a plant that should not be pruned in the fall. Do the clean up for both of these in the spring.

The foliage and flower stems of Ceratostigma plumbaginoides (Leadwort) will provide an attractive display through the fall and winter. The main reason for leaving this plant standing is to mark its location the next spring. Ceratostigma is unusually late to emerge and often waits until it is time to plant annuals before it peeks from the soil. Having some remnants of the plant still present means that that it will not be disturbed while it is dormant.

The tall seedheads of Cimicifuga racemosa (Bugbane), star-shaped seeds of Dictamnus albus (Gasplant) and the horizontal structures of Crocosmia (Montbretia) provide attractive interest if they are left standing during the winter.

Getting Dendranthema (Chrysanthemum) and Lobelia cardinalis (Cardinal Flower) to overwinter is often a tough task under the best of conditions. Leaving the entire plant standing in the fall will help with winter survivability. Even though the plants often have a sprawling way of growing, this does add interest when the snow flies. Letting cardinal flower self-seed increases the chance that some plants may overwinter (even if it is as seed).

Two architectural plants that add dramatic interest during the summer, fall and winter are Echinops ritro (Globe Thistle) and Eryngium planum (Flat Sea Holly). Both of these plants are known to self-seed if the seedheads are left on the plant. If self-seeding is not a problem in the garden leave these plants alone until the spring so that the round and spiny structures can be fully appreciated.

One of the unsung treasures of the perennial border are the Gaura lindheimeri cultivars (Butterfly Gaura). These plants have months of light airy dancing blooms and once the frost comes; they have attractive red tints on the flower stems in the late fall. These turn brown during the winter.

Getting Papaver orientale (Oriental Poppy) to have seed pods for winter interest is a battle. Most often the seed pods are harvested in the summer and fall for floral arrangements instead of leaving them on the plant. With such an attractive seed pod who can blame the early harvesters?

January view at the Ladybird Johnson Wildflower Center, Austin, TX

January view at the Ladybird Johnson Wildflower Center, Austin, TX

Silvery stems and seedheads are the reward during the winter for leaving Perovskia atriplicifolia (Russian Sage) standing until the spring. Since this plant likes to grow with a mass of divergent stems, the effect is quite interesting. Prune Russian sage to 15 cm (or lower) in the spring if killed to the ground by cold weather.

Both the excessively tall Rudbeckia nitida ‘Herbstsonne’ (Black-eyed Susan) and the shorter coneflower perennial staple called Rudbeckia fulgida ‘Goldsturm’ might fall over during the worst winter weather. Nonetheless the “coneflowers” are excellent winter interest plants because of their seed structures and the birds love to feast on the seeds.

One of the best winter interest perennials are the Hylotelephium ‘Herbstfreude’ AKA Sedum ‘Autumn Joy’. The brown spent flowers hold up very well to rain, snow and ice (and look great during all of these conditions). Often the seedheads look so good that they are used in early spring flower arrangements. Don’t touch them at all in the fall.

Several other perennials are attractive during the winter because of their evergreen foliage. These are Ajuga reptans cv. (Carpet bugleweed), Helleborus orientalis (Lenten Rose), Heuchera sanguinea (Coralbells), Lavandula angustifolia (English Lavender), Teucrium chamaedrys (Germander), and Thymus serpyllum (Mother-of-Thyme).

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