Garden Notes: Blooming colors

From strawberries to iris to geraniums, enjoy them all.

Susan Safford

Fireflies are flashing, “Summer is here.” Long-range forecasts predict the Northeast will be on the receiving end of higher-than-normal rainfall, while other parts of the country may have drought.

In the garden

Lots of planting is taking place. Over 95 percent of the world’s plants form symbiotic relationships with mycorrhizae: They help optimize the ability of plants’ roots to establish and gain sustenance from the surrounding soil.

Mycorrhizal products, usually in granular or powder form, are available to use at planting time, and greatly help plants to establish and grow well. They must come in direct contact with roots. There are two broad categories: endo- and ectomycorrhizae. Consult here to learn the mycorrhizal needs of what you are planting.

One suggested use for mycorrhizae is to avoid “rose replacement disease,” an annoying soil condition/roadblock, which makes it challenging, as the name indicates, to establish new roses where others were previously planted. Earlier advice was to wait three years. Using mycorrhizae and organic culture may make it possible to replace successfully and without the wait. (Roses are endomycorrhizal plants.)

Vegetable garden

The fun is harvesting (and eating) strawberries. To ensure more of the same for next year, set the plants’ runners to form fresh plants. (Strawberries are also endomycorrhizal.)

Salad greens grow well in cool temperatures. When summer temperatures arrive, these bolt easily and fast. Find a shadier or cooler location for the next planting of them, or create a tunnel plus shade cloth.

These rains are promoting a lot of weed, but keep at cultivation: They will be manageable. My long-handled, thin-bladed Dutch cultivator hoe is very effective in the alleys and between plants, and enables a light touch. It is similar to one sold by Johnny’s Select Seeds, Eliot Coleman’s collinear hoe.

Ornamental garden

There is a fatalistic expectation of rain during the glory days of peonies and roses, even in otherwise dry springs: “Rain, always, when peonies and fringetree bloom.” Even good staking practices are insufficient to keep all those blowsy heads upright in a heavy downpour: Makes a good case for later blooming, or shorter, peony cultivars, although the classic peonies are impossible to relinquish. Last Tuesday’s inch and Thursday’s inch-and-a-quarter lived up to tradition; I thought the fringetree would burst apart.

Pinching perennials to retard bloom and make bushier plants is still possible, but for the most part, this aspect of control is finished, and plants are on their program to forming flowers. One exception is garden chrysanthemums. And never pinch lilies, which are monocots, with only one embryonic growing point.

Siberian iris were spectacular this rainy spring, but, really, every year these slender perennials, so well adapted to Island gardens, perform well. To keep Siberians that way, lift and divide the clumps, now that flowering is finished. It can seem like backbreaking work, but otherwise, they expand into circles with empty centers, which soon host a colony of dandelions or goldenrod seedlings.

A bed’s soil quality makes a difference in the labor of digging and dividing. Workable soils in good tilth ease these operations, so work in composts and other organic matter to the maximum extent possible. If it is not actively cultivated in for breakdown by soil organisms, mulch — especially the dyed kind — that is laid over a garden in a sort of “undisturbed, inviolable blanket” is mere lookism, not gardening.

Geranium, for gardens

Geraniums, the perennial ones, not the plants of window boxes, lack the color punch of the pelargoniums that confusingly share the name, but are nonetheless a colorful and wonderfully large family. They are a varied and invaluable group of plants, adaptable options for gardens and landscapes, sun and shade, rock garden and woodland.

Occupying 19 pages (!) in the “Encyclopedia of Perennials” (DK Books), geraniums come into bloom in spring, and bloom over an extended period, especially if deadheaded and cut back. Do not underestimate foliage, as the deeply lobed rosettes of most are decorative and ferny-looking, while a good many species show exciting fall color.

The screaming magenta, bushy Geranium sanguineum and its many forms make wonderful rock garden and front-of-the- border plants, and even thrive in wall plantings. G. macrorrhizum and its cultivars are a favorite of mine, with good groundcovering, fragrant foliage, and good fall color: ‘Spessart,’ ‘Ingerwersen’s Variety,’ and ‘Bevan’s Variety.’ Related are the hybrids such as ‘Biokovo.’ The blue or blue-violet geraniums are almost too many to mention, but ‘Johnson’s Blue’ and similar hybrids are widely available and invaluable.

Beyond the garden

Viburnum leaf beetle has been ravaging the undergrowth shrub Viburnum dentatum in Christiantown and other wooded parts of the Vineyard. Plants will releaf if there is good rainfall, but “will struggle if dry,” according to Tim Boland, executive director of Polly Hill Arboretum. Further reading indicates shrubs may be killed in as little as two to three years.

Viburnums constitute a large group of ecologically important flowering shrubs, with global distribution, as well as being a vital component of the designed Island landscape. I consulted Dr. Michael Dirr’s comprehensive “Viburnums: Flowering Shrubs for Every Season” (Timber Press) to learn more about this pest (Pyrrhalta viburni) and the outlook for several favored viburnum species.

The larvae and adult beetles feed on the leaves; as well, females chew holes and lay eggs in stems and branches. “Control involves planting resistant species, removing infested stems after egg laying has ceased, or chemical pesticides.”

Space is limited, so I quote the “Most Susceptible” and “Most Resistant” species:

Highly susceptible: V. dentatum, V. nudum, V. opulus, V. rafinesquianum, V. trilobum

Resistant: V. x bodnantense, V. carlesii, V. davidii, V. x juddii, V. ‘Oneida,’ V. plicatum f. plicatum, V. plicatum f. tomentosum, V. rhytidophyllum, V. setigerum, V. sieboldii.