Garden Notes: Autumn beauty on Martha’s Vineyard

Winning array: a maple, Acer triflorum, puts on fall dress at Polly Hill Arboretum.
Photo by Susan Safford

Winning array: a maple, Acer triflorum, puts on fall dress at Polly Hill Arboretum.

Orion, the Hunter, is a constellation of autumn and winter and has been one of the brightest features of recent starry nighttime skies. Ah, the approach of winter! It seems one either enjoys it or becomes somewhat melancholy. There is, however, plenty to do and little time in which to do it: congenial conditions for outside work are not assured in October. High winds from northern quarters, beating autumn rains, and brisk temperatures suggest that this year mild weather might not be a prolonged phenomenon.

Runoff

The year 2010′s rainfall paradigm appears to be intense, hard rains of short duration, leading to a lot of water for existing drains to handle all at one time. Unfortunately, paving and hardscaping of all descriptions exacerbate runoff and the potential for flooding: water movement is faster, more forceful, and less is able to percolate into existing open ground. If you are contemplating having landscaping work done, take a second look at the layout with water management in mind. Plan for protecting low spots such as cellars, basements, and crawl spaces. (One way is by creating berms to direct water flow.) Avoid creating unintended watercourses and soil erosion. Use permeable pavers. Provide runoff with drainage and catchments.

In the Garden

Prepare indoor spaces to receive the houseplants that have been on outdoor summer vacation. Check them over for insect life and, perhaps, apply insecticidal soap or horticultural oil, with a sprayer, as a pre-emptive measure. Cutting them back is a good practice. Continue also cutting back and clearing out in beds and vegetable gardens — old foliage of vegetable perennials, such as lovage, rhubarb, and asparagus. Compost the debris on your place if possible, for future return to your own soil. Prepare garlic beds by adding humus, compost, organic fertilizer, and working them in. Continue to hill up leeks to attain the longest possible white parts. “Cabbage white” butterflies are still flying; check cole crops, such as turnip, collard, broccoli, kale, and cabbage, and apply Bacillus thuringiensis (Bt).

Autumn Interest at Polly Hill

A walk around the arboretum at this time of year reveals gorgeous fall color among the specimens and meadows, and plenty of ideas for one’s own home planting. Evergreens begin to distinguish themselves as green presences. They stand out against the deciduous plants and foliage, which have begun to color, fray, or tatter through their lifetime of six months in the elements.

Nancy Weaver and Tom Clark of the Arboretum staff recently led a small group through the arboretum grounds, focusing on plants of autumn interest. A partial list of plants, taken from the Arboretum’s website (www.pollyhillarboretum.org) to look for on your own visit includes Callicarpa dichotoma “Issai” (fruit) — purple beautyberry; Cyclamen hederifolium — ivy-leaved cyclamen; Franklinia alatamaha — Franklinia; Osmanthus heterophyllus — holly tea-olive; Rhododendron “Today and Tomorrow;” Rhus typhina ‘Laciniata’ (fruit) — cut-leaf staghorn sumac; Solidago sp. — goldenrod; Symphyotrichum oblongifolium “October Skies” — aromatic aster; and Tricyrtis “Sinonome” — toad-lily.

Scores of deciduous and evergreen holly trees, from stately mature specimens planted early on by Polly Hill herself to youngsters of all provenances, enhance the arboretum’s grounds. Many of the evergreen hollies possess shiny leaves that gleam as the low autumnal light strikes them, turning them into beacons that prompt closer examination.

Yet it is the hollies berries we focus on now, for they glow yellow, orange, to crimson and all shades of red in between. They flag our vision. Obsession with hollies’ berries is not unfounded, the berries themselves being an important ornamental feature and reason for planting this genus. They definitely provide a great part of an owner’s pleasure. “Why doesn’t my holly have berries?” is a frequently asked question in gardeners’ write-in formats. What’s this? Green berries? Tom Clark observed that interested readers might want to take a closer look at their own hollies to track this seeming abomination.

An insect with an interesting modus operandi, a minute fly, the holly midge, is the cause of those green berries. I found an abstract from the “American Midland Naturalist” which briefly describes the insect’s life cycle and ecological niche:

“Green fruits of Ilex opaca [American holly] infested with larvae of holly berry midge (Asphondylia ilicicola) were eaten less during the winter and spring than uninfested red fruits. These results indicate that fly larvae, and their associated fungus, interact with berry physiology to prevent the fruit from changing color, thereby protecting the larvae from frugivory [fruit eating] until spring when the midge emerges and starts the cycle again by laying eggs in holly flowers.” Fruit going from green to red is the signal that many fruit-eaters, humans included, use to gauge ripeness and edibility. How clever for a tiny insect with a couple of ganglia for a brain!

A maple, Acer triflorum, lights up a glade bounded by the Arboretum’s scenic backdrops, its stone walls. Patches of a hardy cyclamen, C. hederifolium, have been planted here and there at their bases beneath great oaks. The beetlebung trees (Nyssa sylvatica) lining the west meadow echo the glow of the fiery sumacs nestled among the reddening grasses.

It is the spiny Osmanthus heterophyllus in full flower in the nursery field near the Littlefield house that becomes the fitting endnote of this walk-through. Not only is it in full, fragrant flower but osmanthus is also a dead ringer for a holly. Yet osmanthus is in the Oleaceae, holly in the Aquifoliaceae. The collection contains a variety of O. heterophyllus cultivars. The photo shows that likewise with holly varieties, some of the shiny deep green leaves are entire: that is, there are no spines. Even the flowers are superficially similar to those of holly, although intensely fragrant and blooming at a completely different time of year than does holly.