Here a wide range of plants have been chosen with long-lasting and strongly contrasting forms to provide interest through the seasons. As the seasons advance, there is a distinct progression. In spring and early summer, only a handful of flowering plants have strong structures with an inflorescence that persists as an ornamental feature into the next flush of growth, such as that of Camassia ‘Alba’ and Zizia aurea. What is particularly important at this time is the role played by many as yet to flower plants with their lush and contrasting colored foliage providing filler and bulk in a supporting role when flowers are few and far between. These include the gray-blue strap-like foliage of Eryngium yuccifolium and the deep red foliage of Penstemon ‘Husker’s Red’.
As the summer comes into full swing the planting increases in height and the display is increasingly dominated by plants of North American origin such as Echinacea, Phlox, and Liatris. At least half of this planting consists of grasses of mixed origin – Molinia, Sesleria, Calamagrostis, and Panicum varieties. With the arrival of fall, the very tallest plants such as the gigantic ironweed, Vernonia, and Eupatorium begin to flower and visually dominate the back of the planting. Eventually, bright colors far and few between yet can seem even more enchanting in contrast to the many earth tones represented by the persistent structural seed heads of earlier flowering plants and the variations of yellow and red-colored fall foliage. Asters such as ‘Constellation’ and ‘October Skies’, as well as Solidago semperverins and Rudbeckia ‘Henry Eilers’, are particularly striking at this time. As winter strengthens its grip, all that will remain are the skeletons of plants with a bit of colored foliage here and there. Many of these forms will remain intact up until the first heavy snowfall before which numerous early frosts will coat and highlight their spent foliage and seed heads with a layer of crystalline hoar frost. This ethereal display is the last of the garden’s expressions until spring.
What is most evident about this meadow-like planting technique is that the depth of the border in places is often as deep as it is long, which allows for greater layering of plants, with larger clumps used in repetition such as seen in open grassland. Furthermore, the depth of the planting area allows one to walk into the planting thereby gaining a significantly different perspective as they progress along a designated path, the effect of which is considerably more intimate and inspiring than looking at the planting from the outside. Like all the display gardens, the composition of the Perennial Meadow is largely determined by predominant environmental factors, in this case, that of heavy clay soil. And, like all the display gardens, this has involved a lot of trial and error to find a good ecological fit. Culturally this garden is dealt with similarly to the Deschampsia and Carex Meadows, and for similar reasons, though it is sometimes left standing longer for the early winter display described above. Before crashing down with the first heavy wet snow, using shears, the dead top growth of plants is incrementally chopped and left lying as fertilizer and mulch at the base of the plant, further incorporated with the use of a mulching mower set on high come spring (as opposed to removing and composting the material in a specific location). Equally important is that this mulch reduces the heaving of plants from repeated freezing and thawing, a particular issue with clay soils. A note of caution – with this method is the possibility of promoting self-sowing to an extreme. Some wilder garden plants are prolifically self-sowing and have high germination rates so must first have their seed heads removed leaving the rest of the plant to be chopped and remain. When one begins to maintain a garden in this way it becomes clear the added benefit of grasses with the copious amount of biomass they generate. On average most broad-leaved plants (forbs) are nothing but stems come late fall. Grasses thus have a strong ecological appeal in sustaining the soil and the garden ecosystem that depends on it.
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