Garden Notes: Pruning reviewed

And a tidy edge on your flowerbeds is preferred.

—Susan Safford

Finally, it is spring. Deer are moving around, as the number of their roadside corpses proves. Drive with care!

A big part of spring garden maintenance is pruning woody and shrubby plants. They comprise a lengthy list, and produce a large amount of debris.

Note that the part to be removed is fully visible; most “uh-oh” moments arise from being unable to see the cut clearly. First though, check that pruners and loppers are sharp, to protect plants with clean cuts and your own wrists from stress. There are many online videos that demonstrate sharpening pruning tools. Jeremiah Brown at Vineyard Gardens provides a tool sharpening service.

Always cut back to a larger branch of the trunk. Do not leave stubs. Make undercuts on larger branches, and keep the branch collars, swellings around the branches’ base. Keep your pruners with you: The time to prune is “when the tool is in your hand.”

The rule I follow for flowering shrubs: If it blooms before June 21, prune immediately after flowering, e.g., forsythia. If it blooms later in the season, prune until June 21, e.g., rose of Sharon, hibiscus, Pee Gee hydrangea, crape myrtle.

Garden trees whose sap bleeds should be pruned while dormant: e.g., dogwoods, maples, birches. Conversely, magnolias should be pruned only when in active growth. It might help to keep a garden notebook for some of this info.

Forsythias benefit from renewal pruning, removing some stems at ground level each season. The older canes have a different appearance, often warty, from the younger, more vigorous ones. Long, whippy growth will tip-root if it comes into contact with soil, but by the same token, these can be taken and “quick-set” for propagating additional plants, a hedge for instance.

We are pruning buddleia by cutting back the stalky growth to buds lower down on the wood of the previous season. Be aware that “growth follows the knife”: Pruning hard often results in regrowth to replace what was pruned away. If plants are growing strongly, try pruning more lightly and see what kind of results you get.

We are pruning clethra. The fragrant August bloomer is a superb native plant for woodland, shady, or damp places. It suckers and makes clonal colonies if happy. When it is trimmed back now, the growth will be thickened, and more of the small white flower spires will be produced.

Prune trumpet vine. Hard. Although it is beautiful, seeing this plant positioned near houses and buildings is something I dislike, although otherwise it is a glory of high summer, and of course, a magnet for hummingbirds. It has a way of popping shingles off walls and sills off foundations. Rogue root offshoots spring up far from parent plants, and are very tough to control. Prune back the long whiplike extensions so there is merely a trunk; it grows and flowers on new wood.

Pruning of roses started earlier in the spring, and is ongoing. Cut out the brown or discolored canes, as well as those branches and shoots that are spindly. Bring the whole plant down closer to the crown with hybrid teas, floribundas, and easy-care roses such as Knockouts. Trim laterals on climbers back to about four inches, or to three or four buds. Side-dress each with two cups of organic soil fertilizer.

Panicle hydrangeas may be pruned hard in spring, blooming as they do later in summer; or may be left to grow tall and treelike. Arborescens-type hydrangeas, such as ‘Annabelle,’ are pruned down nearly to the ground in spring.

Mophead (H. macrophylla) hydrangeas are cleaned up, with winter kill removed, as early in spring as possible, but are otherwise left alone, since older cultivars form flower buds the previous season. Other sub-shrubs, such as hypericum, caryopteris, potentilla, and Montauk daisies, are trimmed back by about a third.

NOT being pruned at the moment: lilacs, forsythia, early flowering viburnums, flowering quince, and anything woody and spring-flowering; wait until flowering is past.

Garden craft

Now is the time to edge flowerbeds, and I do not mean install a metal or plastic product. These may be good for some applications: for instance, institutional landscapes or keeping driveway peastone in place. If edging is dislodged by tires or frost heaves, or if quack grass runs underneath it, as frequently happens, re-edging with an edging tool would be much simpler than reinstalling.

A recent Guardian article about British gardening’s young stars,, quoted the pet peeve of one of them, Tamara Bridge, as bad lawn edges: “I like a nice crisp edge with no tufty bits. If you have a flowerbed with an edge on the lawn, it needs to be neat and tidy.” I agree. Learn to handle an edging tool or, more effortful, a flat spade. Both are kept sharp with a file.

Live and let live

Typical homeowners are faced by a wide array of advertised problems and products to deal with them. I was at an Island garden center when an old lady approached the counter with a plastic container in hand. “How can I kill these?” she asked. We all looked in — What was it? Scorpions? It was a very small spider. To her credit, the salesperson explained she could just dump it outside.


In the garden

Soil temperatures are 61º to 62ºF. Tomatoes and beans prefer soil temps above 60º, and may be set back if planted out too soon. Use hotcaps or Reemay for early planting. Side-dress perennials with organic soil fertilizer, and pinch as needed. Cut out flowering stems of rhubarb. Make nightly tick checks a habit.


Polly Hill Arboretum

PHA will hold a Horticulture for the Home Gardener program on Saturday, May 12, from 10 am to noon. Join PHA horticulturist and arborist Ian Jochems for a look at the basics of horticulture, covering the essentials of how to plant everything from seeds and bulbs to shrubs and trees. Participants will learn about proper plant care, mulches, soil amendments, basic integrated pest management (IPM), and will get hands-on practice with various tools. The fee is $20 for PHA members, $35 for nonmembers. Preregistration is required. Call 508-693-9426 to sign up.