Polly Hill Arboretum is the Vineyard’s impresario of spring. Hellebores and witch hazels are at the forefront, but for the observant, there are many more heralds of the season. The PHA camellia collection, mainly Camellia japonica specimens, would often be features of the March winter walk most years, but not this Saturday.
Flowers and buds on many of the camellias are browned and blasted from cold, except at the tippy-tops, demonstrating clearly the temperature differential that a few feet create: coldest air collects at ground level. The March winter walk is Saturday, March 9. Dress for the weather and meet at the visitor center at 10 am.
In the years since Polly Hill planted these pioneering island-grown camellias (some now 10 to 12 feet tall), much breeding and hybridizing has been undertaken to extend the so-called Camellia Belt into the lower number USDA hardiness zones, such as our zone 7a. We can give thanks to Drs. Clifford Parks and William Ackerman for their pioneering camellia hybridizing work in the United States.
The hardiness zone of typical Camellia japonica is USDA zone 8 and higher (warmer), making camellias emblematic shrubs of the milder portions of the U.S. However, by the patient hybridizing of hundreds of crosses of less-known, cold-hardy camellia species with the japonicas, dozens of beautiful but hardier plants have come into commerce. With a preponderance of sandy, acidic soils, the Vineyard is a great place to trial them.
The Clifford Parks “April” series cold-hardy hybrids (many but not all featuring the word April in their names) were introduced in 1995 and are recommended for USDA zones as cold as 6b. Noteworthy clones are ‘April Dawn,’ ‘April Rose,’ and ‘Rose Twilight.’
The hybrids with C. sasanqua using hardy species and cultivars to introduce greater hardiness and showier blooms, such as ‘Angel’s Kiss,’ ‘Pink Butterfly,’ and ‘Scented Snow,’ are categorized separately from cold-hardy hybrids but many are hardy to zone 7a and are fall blooming.
Many of Dr. Ackerman’s selections, but not all, contain Winter or Ashton in their names. Look for clones such as ‘Snow Flurry,’ ‘Winter’s Charm,’ and ‘Ashton’s Pink.’ For much background and helpful information about the breeding efforts and individual hybrids, look for Dr. Ackerman’s book “Beyond the Camellia Belt.”
The book and a wide selection of camellias and other choice plants are available through Camellia Forest, camforest.com, the North Carolina nursery started by Dr. Parks and now run by his son. Another fine nursery, Fairweather Gardens, fairweathergardens.com, is a cold-hardy camellia source nearer our region.
Camellias in containers are supplied by Island garden centers during the season. In general, choose camellias with names referring to cold, such as ‘Pink Icicle,’ ‘Frost Princess,’ or ‘Winter’s Dream.’ Choose spring planting over fall planting and site carefully: sheltered woodland, north side of stone walls, or shaded locations, preferably on sloping ground to let cold air flow away. Use moisture-retentive, humus-rich acidic soil that is nonetheless free-draining. Mulch with compost.
From the soil up
Compost reverses compaction. As we assess the winter damage and dispose of debris, I want to give composting a shout-out, returning Island-generated organic matter to Island soil, one way or another.
Some of the winter damage that occurred is part of cycles that are larger than we are. I am attempting to understand and learn from them. As an example, sassafras and red maple in island woodlands (and black oak) have tops broken out by snow load. These trees are part of the ecological succession of this area from pasture to woods.
Along with red cedar and grey birch, they constitute a class of encroaching, pioneer tree species that provide shelter and shade for the black oak and other hardwoods that come along next. Here and there one sees well-preserved stumps of red cedar in deciduous woodland’s midst, evidence of the wood’s rot-resistance outlasting its ability to survive shade.
First, as the sassafras and black oak were being weakened — out-competed for resources — some form of structural damage occurred, either invading disease or insect or both. The snow load that broke out the tops was probably not the root cause of damage, which was the maples’, sassafras’s and black oaks’ place in the successional order!
I sometimes hear repeated a piece of [sub]urban myth: “beeches kill oaks.” While that might appear to be the case, what happens is beeches — hickories too — are programmed to succeed oaks, at least black oaks. They gradually spread throughout “oak habitat,” altering it to suit their own needs.
While the ecological succession in woodland takes place before our eyes, no one knows what the so-called climax habitat really consists of. Successional climax is a theory undergoing reappraisal by evolutionary biologists, and it is not only what is happening before our eyes, but also what is happening beneath our feet.
“As in farms and gardens, soil is the foundation of the health of a forest. When trees seem to be in decline, we often look up into the crown for the source of damage — for ice scars, wind damage, fungi and insects — but we should probably look down at the soil. Even if a tree is infected by fungi or insects, its ability to heal and maintain its health depends on its access to water and nutrients from the ground. Healthy trees produce chemicals to ward off invaders and repair physical trauma. When soil compaction suppresses their ability to combat illness, every other ailment is more damaging.” – Andy McEvoy, “Manage Your Forest By Managing Your Soil,” MOFGA Journal, Dec. 2012.
Rebecca Brown of Edgartown will address such issues, and more, in her class, “Optimizing Livestock Health: From the Soil Up, ” on March 14 at the Agricultural Hall at 7:30 pm. Admission is free and the public is welcome.