Garden Notes: True colors

From native viburnum to colorful peonies, the Island is alive with color.

White-flowered doublefile viburnum adds calm to Technicolor shrub borders. — Courtesy Abigail Higgins

For those of us privileged to have gardens or a patch to grow, gardens are our windows into a world of existences that put our own into perspective. Like the greater world, gardens are not always places of luxurious calm and order, but through them we know what that can be.

The gift of May is awakening life, of flowers and buzzing insects, fragrance, early morning sunlight filtered through newly unfurled greenery — try to bring that with you as you head out into mundane life, and June.

The general rejoicing at the news that there will be a 159th Agricultural Fair (August 19 through 22) this summer is gratifying. Keep in mind that what you are planning and planting now will become your entries and exhibits. Broaden the scope; widen the window. Dahlia competition will be hot. As much horticultural and vegetable excellence as can be mustered is the way to make the Ag Hall displays memorable.

In the garden

It is beginning to look as if seasonal weather patterns are blanking the Island on rainfall. We can make use of fallback strategies, such as container displays of drought-tolerant plant material (think succulents, gray, or furred foliage), rain barrels under downspouts, and judicious mulching. Water use for those chem-lawn green expanses comes from somewhere: the Island’s aquifer. Running irrigation to keep geese off lawns — not wise use of the shared resource.

Sad to say, I saw no mourning cloak or spring azure butterflies this year, but carpenter bees abound, and their galleries are visible even on painted wood. Capable of widespread damage in wooden structures and considered to be a nuisance, carpenter bees do, however, perform pollinating functions.

Soil temperatures in my vegetable garden are holding at the lower end of warm: about 66°F.

Peonies are budding fast, so it’s a last chance to stake, especially the taller- or stronger-growing cultivars, before hoped-for rains arrive. Ants may be seen harvesting the honeydew the buds exude; this is not a problem, and requires no action.

Early strawberries are in flower and berrying; it will be time to net shortly. Keep asparagus cut. It used to be advised to cut asparagus spears just below soil level; this, however, is no longer recommended.

Cut and burn galls of Exobasidium vaccinii fungus parasitizing on azalea, blueberry, rhododendron, and other members of the ericaceous family, before they ripen and spread spores.

Flowering shrub border

The flowering shrub border is one of the most delightful ways to achieve screening and privacy of gardens. Lilacs, Syringa vulgaris, and cultivars were spectacular this year; but now the season progresses into the Korean and hybrid forms, and azaleas and rhododendrons.

Deadhead lilacs where practical, because seed production is not a critical part of lilac culture, but defer major pruning until after lilac borer activity is past. I see almost no Island plantings of lilacs that do not exhibit the keyhole-shape borer damage on older wood.

One of the paramount screening plants, rhododendrons do well in Island gardens, if deer browse is no problem. If every appealing color is indulged, and there are many, the Technicolor garden show put on by azaleas and rhododendrons can be head-spinning. It is my view that getting plenty of white into the mix enables greater appreciation of vibrant color.

In the landscape size category, longtime early rhododendron ‘Cunningham’s White’ has peaked, but there are others to come, such as ‘Boule de Neige’ and ‘Catawba White.’ Azaleas (botanically also rhododendrons) in white or very pale colors are readily available too. Rhododendron ‘Delaware Valley White’ and ‘Sir Robert’ are two easily found standbys that dilute the intense colors of ‘Exburys,’ ‘Knaphills,’ and landscape-scale rhododendrons, such as ‘Roseum Elegans’ and ‘Scintillation.’

One of the best plants for screening and bringing the carrying power of white into gardens awash with riotous color is not a rhododendron at all but a viburnum: Viburnum plicatum f. tomentosum, the doublefile viburnum.

Native viburnum is widespread on Martha’s Vineyard, primarily in the form of V. dentatum, arrowwood, and occasionally as V. cassinoides (now V. nudum); it and its non-native relatives — there are a lot to choose from — do well here. However, branching out into the greater viburnum world requires a reliable guide: Michael Dirr and his “Viburnums: Flowering Shrubs for Every Season.”

Dirr has a lot to say about doublefile viburnum: “A classy shrub, horizontally branched, with white lacecap flowers marching two by two along each branch’s length … In its finest forms, broad-spreading, horizontal branches fill an eight- to 10-foot-high space, extending wider … Every garden has a spot for a doublefile.” Add in colorful fruit and showy autumn foliage, and you have something worthwhile to calm those Technicolor azaleas.

‘The scourge of the South’

‘Bradford,’ ‘Aristocrat,’ ‘Chanticleer,’ and ‘Cleveland’: These are all cultivars of the Callery pear, Pyrus calleryana. They have become known as “the scourge of the South.” They break, they stink, they reseed, they grow murderous thorns, they invade ecosystems everywhere throughout the South.

Due diligence is required to guard against bringing anything so noxious into an ecosystem, especially an island, whether it be chipmunks, skunks, or nuisance plants. It is therefore terribly disappointing to see Callery pears offered for sale by Island tree sellers and planted by Island landscapers.

Why would numerous Southern states have put these pears on their lists of noxious, invasive plants? South Carolina even offers a bounty to owners who destroy them!

This is one of the worst trees you can plant — go to this Google page to find numerous links to articles explaining why:

Polly Hill Arboretum

PHA has published its Summer-Fall 2021 program of lectures and workshops. For more information, visit the website at