Welcome to summer, which officially started with the summer solstice last Sunday. It was a rainy day; perhaps we can take it as a good sign that adequate rain will fall on us for the rest of the season, here off the southeastern coast of Massachusetts.
It is also rose time on Martha’s Vineyard. Roses’ (and peonies’) season of bloom seems to coincide with rain. The cost is some spoiled flowers. A few of the most beautiful roses and peonies “hang their heads” in rain, due to large cupped blooms and/or possibly weak stems. Despite that, they do best with about an inch of water per week, and natural rain provides it best. Without it there will be marble-size peony buds that never progress and open, or a myriad of rose problems. More about that below.
I fielded a recent question about uneven “bloom” on kousa dogwoods, Cornus kousa. I cannot say for sure, but it probably has something to do with something unevenly affecting the roots that feed the unevenly blooming branch, such as compaction.
The condition appears quite commonly, and is sometimes nothing more than a slight delay among different parts of the tree in leafing out and producing the “flowers” — in quotes because they are actually ornamental bracts surrounding the inconspicuous, true flowers at their center. Other specimens may manifest dieback, and this might be due to insect damage or disease.
Island gardens host large numbers of these Asian cousins of the native North American Cornus florida, and many are purely spectacular just now. Striking fall color is an additional plus. To gauge the eventual spread of a kousa dogwood, visit the dogwood alleé at Polly Hill Arboretum, composed of mature specimens that are wider than they are tall! Dogwoods in general are understory trees that prefer free-draining, fertile soil, high in organic matter. They make good specimen trees for gardens that also include nearby shade trees.
Named cultivars, of which there are “136-plus cultivars and varieties” (M. Dirr, Manual of Woody Landscape Plants), exhibit different, predictable growth habits. Examples that are more compact, weep, or have a columnar form, and are worth seeking out, include ‘Baby Splash’ (dwarf, variegated), ‘Doubloon’ (tall, slender habit), ‘Dwarf Pink’ (dwarf on own roots, 8 feet by 6 feet), and ‘Weaver’s Weeping’ (strongly weeping branches, exceptionally heavy flower display).
Roses exercise a potent hold on gardeners’ imaginations. There are many ways to grow the elegant symbol of love and beauty. I am not going to argue with those who have their program of chemical fertilizer, fungicide, and pesticide application carefully worked out. What is beyond dispute is that many landscaping problems may be solved with a carefully chosen rose species or cultivar.
I have found what works for me: roses, well-chosen, in good soil produced by plenty of manure (and luckily, my henhouse supplies what the roses here at my place need), water, and sunshine. My rose list includes the following cultivars, all healthy and reasonably trouble-free for an unirrigated, informal Island garden: Climbers ‘New Dawn,’ ‘Westerland,’ ‘Aloha,’ ‘Coral Dawn,’ ‘America’ and its sport ‘Pearly Gates,’ and an unknown large-flowered, tough and beautiful pink climber that came from a teardown. Shrub roses are ‘Carefree Beauty’ (one of the parents of the original ‘Knockout’ rose), ‘Abraham Darby’ (may be grown as either a shrub or a short climber), ‘Carefree Celebration,’ and ‘Nymphenburg.’
But there are many roses I would not consider it worth my time to coax and coddle along to look good and do well, even if they were “planted by my grandmother.” For example, roses that are heavily predisposed to black spot, such as the original ‘Blaze,’ are a poor choice for Martha’s Vineyard, with its fogs, high humidity, and many airborne bacteria.
Most books about roses and rose growing will note flaws of individual cultivars, including cold hardiness, the above-mentioned “hanging their heads” from rain and “balling” from botrytis, and susceptibility to black spot and to powdery mildew.
With the advent of modern rose-breeding programs in the United States, Canada, and abroad, it is possible to have the healthy, luxurious roses of one’s imagination without poisoning oneself and one’s soil. Most gardeners know about the ‘Knockout’ series of roses that William Radler bred in Wisconsin; they have revolutionized rose growing for rose aficionados of every skill level. However, there are equally interesting and beautiful roses from other breeders.
The English roses of David Austin have been as notable as the ‘Knockout’ series in their ability to give fabulous results to novice rose growers, with one positive exception: one of their standout attributes is fragrance. Many “easy” roses, such as ‘the Fairy’ and the ‘Knockout’ series, have faint to no fragrance, but have been worth it to those who had been unable to have success with temperamental hybrid tea roses, and were willing to forego scent in order to have a rose that would grow and flower.
Series such as the ‘Oso Easy,’ ‘Drift,’ and ‘Romantica’ roses also aim to allay performance anxieties among rose-growing gardeners. There are a lot out there. Before purchasing and planting, read the pot tag carefully; if possible, even do some Internet research prior to purchase of the plants you are interested in.
A hazard not always mentioned in replacing a failed rose with another is rose-replant disease: “Do not replace a rose that has failed with another in the same spot.” A way around this is to follow the advice of Fine Gardening:
“Add lots of well-rotted manure or good garden compost to the soil. Treat the new roses with mycorrhizal fungi either by brushing it on, putting it in the hole, or soaking the roots in them. Never use chemical drenches or all-in-one rose treatments, because you can harm the soil.” Read more here.