Garden Notes: Boxwood is a lifetime plant

So it’s worth it to do a little reading.

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The height of the garden year has already come and gone: summer solstice. Not to worry; there is plenty of action still to come, although solstice energy reminds gardeners that everything on earth is light-driven: plants, gardens, and ourselves. And now summer is here!

The hay that is being taken off Island fields is “stored summer sun”: solar energy for livestock to convert to fats and proteins. We reap the benefit, since humans are not grass eaters.

Paying attention to boxwood

Across the bed of my truck in a garden center parking lot, a pleasant interchange with a gardener took place. She asked me whether I would be interested in another project, and while declining another project, I asked her to tell me what the problem was. She described a problem with established boxwoods in her garden, including one that had died over the winter.

Those who have boxwood in their gardens are usually very attached to them. These slow-growing, enduring plants provide an element of timelessness — even mystery — to gardens, where they often form a critical part of the garden architecture.

Without actually inspecting the plants, it was unwise of me to come to any conclusions; and so I tried to give some general information that might help with finding a solution. I repeat it here because boxwood now faces several issues in our area.

First, over the years I have known numerous people, including people in the Biz, refer to “boxwoods” (Buxus spp.) that were actually Japanese hollies (Ilex)! Confirm the plants in question are actually buxus.

(Several Japanese hollies, including I. crenata and I. crenata ‘Hetzii,’ bear a resemblance to buxus, and are actually now widely used to substitute for them where boxwood diseases have caused a problem in their use. Nonetheless, Japanese hollies have their own set of possible problems.)

Disease problems with boxwood — and there are several, fungal and bacterial — have both environmental and situational causes. Lab analysis is necessary to reveal the explicit pathogen. While many plants are tough and undemanding, modern landscape practice has imposed problems.

Many longtime Islanders know of venerable Island houses guarded by a set of equally venerable boxwoods flanking the dooryard: tough, untended, and seemingly ancient. Let the place change hands or come under the care of a mow crew and irrigation, and problems may ensue.

The root systems of the boxwoods we commonly plant here are fine, and near the surface. Locations with poorly drained soil, irrigation heads, or downspouts may lead to problems. I had this at my house: Dwarf boxwoods that had been in place for 25 years began to fail over a winter with unusually heavy downpours. They were adjacent to a downspout, and essentially began to drown. I had to cut out two-inch-thick wood in order to save the plants. They still look like amputees (boxwood is tough and wants to survive!), but are otherwise doing well.

Boxwoods in turf are vulnerable to string trimmer damage; I have seen this in several gardens. If they are sheared (a no-no, actually, with the increasing incidence of boxwood blight), instead of being plucked, a layer of dense foliage forms, like a carapace that does not admit air and light to the plant’s interior. Debris and dead leaves accumulate, held in the interior of the plant, fostering (festering?) the potential for diseases. In addition, every cut leaf surface is a disease entry point and source of stress to the plant.

Just today, working in a garden with both older and newer box, I noticed one whose contour had a broken-apart appearance. I looked inside and did not like what I saw: wet-looking and discolored leaves. This plant needed immediate thinning. I cut out handfuls of seven-inch sections to admit more light and air into the plant’s interio,r and will keep an eye on it.

These two links, to pdfs from Virginia Cooperative Extension (bit.ly/VABoxwoodInfo)

and Saunders Brothers (bit.ly/SBonBoxwoods), give you almost everything you need to know about boxwood culture. I recommend going through them to learn everything you need to know about keeping box in the garden healthy for years to come, for these are truly lifetime plants.

In the garden

Now is time to deadhead, prune, or shape early and spring-blooming shrubs. These include the very early, lemony-scented Lonicera fragrantissima, viburnums, weigela, rhododendrons and azaleas, spirea, and kolkwitzia.

The spring bloomers form their flowers on wood from the year before. If grooming is performed now, there will be no loss of flowers next spring. Since I gained awareness of the widespread damage lilac borer causes Island lilacs, I have come to restrict pruning of lilacs now to removal of seedheads only, no wood larger than that. Lilac borers use scent of cut wood to locate places to lay the eggs of their larvae. Save shaping and removal of old wood for later in the season.

Keeping the vegetables coming is a challenge when heat and drought kick in. Salad greens especially prove susceptible to heat as we head into the hotter part of summer. Small succession sowings of lettuce, beans, spinach, radishes, and other quick-growing crops make the most sense. Prolong pea harvest by keeping peapods picked.

Crabgrass is emerging, especially annoying in lawns, and in peastone and beds. So are seedlings of various biennials and pollinator-friendly garden plants. If it fruitfully reseeds, it is a pollinator-friendly plant! Cases in point: Verbena bonariensis; several members of the milkweed family, butterfly weed (Asclepias tuberosa) and swamp milkweed (A. incarnata); cilantro and arugula in vegetable gardens; and foxgloves. You will have to decide what to keep, weed out, or relocate. Remember that next year’s low-cost, low-effort blooming plants are this year’s seedlings.

 

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