Garden Notes: Late summer

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As summer moves through its solar cycle, nights are cooler with dew, shadows are deeper, and midday sun intensifies with infrared rays. It feels like early fall weather, which children greet with groans of impending doom: Summer’s over! As “growns,” we view it differently, and greet it with relief: fewer hordes, less traffic, better sleep, less crazy.

Gardens emerge or retreat into altered patterns of light and shade, as the sun’s transit sinks lower crossing the sky from dawn to dusk. Lily of the valley is a shade-loving groundcover. A formerly fully shaded bed of it shows sunstruck, browning foliage in the newly sunny parts, while shaded foliage remains green. If your lily of the valley is browning out unattractively, try moving it to a shadier site.

Short-day flowers, such as dahlias, asters, late hostas, and more, color the late summer garden; they are worth the wait. Others, such as foxglove, phlox, and annuals may be coaxed into extending bloom with deadheading and watering.

As part of late summer garden life, in addition to the welcome pleasure of the dahlia parade, is the less welcome increased yellow-jacket activity. Although these too are garden allies, it is sometimes hard to hold them in high esteem when they alight unexpectedly upon fruit one is eating, or inhabit the raspberry patch. It is interesting to know that skunks predate on yellow-jackets in their underground nests, and can wipe out a nuisance nest in a night.

Plan for rain

The Island certainly received enough water in the August 19 downpours. These rain events may be a dress rehearsal for later tropical depressions going forward. Gutters and downspouts need to be able to handle increased flow, or there may be basement leakage and damage to foundation plantings grouped close to buildings. Scout locations for swales and rain gardens where needed.

Swales and rain gardens are depressions and plantings of thirsty plants that hold and infiltrate rainfall down, rather than horizontal (runoff). Clethra, colorfully stemmed willows and dogwoods, mallows and hibiscus, inkberry, Joe-Pye weed, lobelias with startling red or blue flowers, and elderberry are a few good subjects, but there are dozens more.

Vervains

It’s not native, it’s not fragrant, it is not particularly showy; it does not have a particularly long vase life. However, this unpretentious little flower on pencil-thin stems will draw in more interesting garden wildlife than many of the showier things we could plant.

Sprinkled through a sunlit bed, Verbena bonariensis does a nice job of punctuating other larger or showy individual or flowering clumps. When a small bird is observed swaying atop a verbena, it is not known whether it is pecking at its seeds or at the protein of a painted lady caterpillar.

Hummingbirds, goldfinches, magnificent swallowtail and monarch butterflies, in addition to skippers and hairstreaks (and butterfly larvae), and other small birds are all attracted to the purple haze of a stand of free-seeding verbena bonariensis in sunlit gardens. It is a real magnet for them. And that is not including much other unseen, nocturnal wildlife that may visit while we sleep: moths, bats, and beetles.

Widely available but not always utilized, Verbena bonariensis is available as seed or to buy as annual six-packs. Once introduced to a garden, its seedlings will remain to appear prolifically but not problematically, and do best in sun and well-drained soil.

On the other hand, there is also a vervain that is native, is fragrant, is quite showy, also has a long period of bloom, and makes a good addition to bouquets: Verbena hastata, or blue vervain.

Look for this beautiful native wild flower in damp meadows, especially up-Island, and in discerning nurseries and garden centers.

Tree care

A black oak (Quercus velutina), likely between 60 and 80 years old, of beautiful form, located in a garden where we work, is to be removed this fall. In spring it did not leaf out. Upon closer inspection, it had been repeatedly and ultimately fatally damaged by years of mowing and string trimming at its root flare.

This is partly a consequence of the unrealistic landscape ideal, à la “milord’s deer park,” of stately shade trees arising from perfectly manicured greensward. Many beautiful trees are maimed or lost due to this vision, which is inimical to the conditions most trees require.

As has been previously mentioned in “Garden Notes”; a tree’s root flare is “where a tree lives.” Recurring injury to the crucial physical part of the tree is usually fatal. Perhaps not immediately, but eventually.

As pictured, when planting trees in lawn, take care to create a buffer zone of mulch, groundcover, or even weed-free cultivated soil in this critical zone.

In the garden

Sort and clean cured garlic bulbs. Save the biggest and best for seed garlic to be planted later in fall.

Prune wisteria whips back to about seven inches, where the fat, brown flower buds are located (bit.ly/RHS_WisteriaPruning).

Continue deadheading and weeding, especially around and under spreading perennials; goldenrod, dandelion, and crabgrass germinate in these locations.

Begin to flag or take photos of perennials in need of division or transplanting. Tag dahlias for identification once they are blooming.

Inside garden

Take cuttings for fresh plants for the coming summer. Geraniums, plectranthus,  plumbago, hibiscus, coleus, decorative ivies, begonias — these are some you might want to propagate. If successfully grown, they become plants you will be congratulating yourself for having a supply of, or for gifts.

In anticipation of unexpected frosts, prepare houseplants and tropicals for overwintering. Trim them back to a manageable indoor size by removing about one-third the length of the shoots. Reduce watering, and eliminate fertilizing. It is not always indicated, but spraying plants with horticultural oil or insecticidal soap reduces the likelihood of bringing insect pests indoors bit.ly/CF_WinteringSummerPlants.

Hurray for Labor Day!