Garden Notes: Cutting back

Perennials in need of dividing.

Susan Safford

Dewfall is heavy. Aloft at dusk, bats find plenty to feast upon. The meadowsong chorus swells as early fall approaches — the chorus of myriad stridulating insects that is backdrop to these last days and nights of summer.

This appears to be a mast year for beech; therefore we can expect a 2020 bumper crop of squirrels, chipmunks, voles, and well-fed flocks of migratory grackles and blackbirds passing through this fall, heading south.


Cutting back perennials

Many perennials will be seen to have increased and spread, and to be in need of dividing. The general cutting back of perennials, and seeing what’s what, begins now, but September is also the recommended month for lifting and dividing peonies and bearded irises.

Depending how full beds are, something the British garden writer Noel Kingsbury likes to rant about (“Mind the Gap,”, many discoveries await, such as the trowel that has gone missing all summer, or, less happily, nests of white-faced paper wasps or ground-dwelling yellowjackets.

The following advice is slightly tardy, but due to mild and lengthy Vineyard autumns, not much. In addition to the above-mentioned cutting back and dividing, certain gray-leaved plants, such as santolina, artemisia, and lavender, benefit from cutting back to encourage tighter growth near the crowns and keep them well-leaved. Do this now, judiciously.

Another wonderful gray-leaved plant for the sunny, dry garden, Stachys byzantina, lamb’s ears, makes much growth, and usually needs cutting back and grooming. Otherwise, wet weather converts it into soggy mats.

If you have planned ahead and prepared some of the smelly comfrey tea described here earlier ( to use as a drench in these operations, the newly planted divisions will come through the operation with added insurance.

Comfrey, and comfrey tea, is the home gardener’s tool, but could be used by commercial gardeners as well. A crop of comfrey is undemanding to grow, increases (without permission!), and has many uses; a nonseeding form, Bocking 14, is usually recommended for this purpose.

Compost tea needs no introduction, having pretty much entered the debate, at least for home gardeners, and a spray made from milk has a longtime history as a homemade control for powdery mildew, which may be exacerbated by heavy dewfall.

In fact, the use of a variety of nontoxic sprays to deter foliar diseases is a topic that deserves and needs further investigation. Little profit comes from home remedies; therefore little scientific time is wasted on them. However, it cannot be prudent to expose ourselves in order to “save” our plants.


Basil introductions

Among plants commonly afflicted with spores of downy or powdery mildews are culinary basils (Ocimum basilicum). Rutgers University has produced four basils that are highly resistant to downy mildew, good news for growers and those addicted to its flavor ( Next year, look for Rutgers Devotion DMR and Rutgers Obsession DMR. 


Dahlia culture

Dahlias come into their own in late summer and early fall until frost, which makes them the perfect wedding flower here on the Vineyard. Dahlias are sun- and heat-loving plants. Some enticing cultivars attain heights of five feet or more, usually requiring staking unless grown in very protected gardens.

Dahlias are simultaneously easy to grow and at times afflicted by problems, such as slugs, snails, spider mites, powdery mildew, and fierce, leafhopper-farming ants. Insecticidal soap and horticultural oil keep most of these nuisances at manageable levels.

Follow this link to an interview by Kath LaLiberte, to read about the methods and dahlia culture of Alicia Schwede. Schwede is a West Coast grower and florist who grows and markets more than 700 dahlias, among other flower business:

An excerpt: “Here’s the secret. When Alicia cuts a dahlia, she always cuts a long stem — right back to one of the main uprights. This means sacrificing unopened buds, But if you can steel yourself and only cut long stems, your plants will produce more long stems. Of all Alicia’s cutting garden tips, I found this one to be the most valuable — and the hardest to do!”


In the garden

If your garden is blessed with plentiful birdlife, well then, you will also have the dubious blessing of plentiful bird-sown woody vines and plants. Along with everything else, they made phenomenal growth this season. Check in beds, shrubs, and hedges for wineberry, Virginia creeper, bittersweet, honeysuckle, weed clematis, grapevine, and of course, poison ivy, and pull them before the roots become entrenched.

Give houseplants vacationing outside a good checking before bringing back indoors. This morning I sprayed half a dozen with horticultural oil to control whitefly, minute scale, and mealybugs that are eternally there, whether or not they are visible to the naked eye. Good time, too, to refresh soil or repot as needed.


Mango Lime Salsa

This is a wonderful complement to baked or grilled fish, in case fishing family or friends get lucky and come home with a striper. It was going to be included in the August Sauces portion of the previous Garden Notes, but got lost in a word-processing fiasco.

The seeds of the cilantro I intentionally let bolt earlier in the summer have now germinated, promising a fresh crop of the essential salsa ingredient. Apart from the mangoes, olive oil, and maybe the limes, all ingredients are homegrown:

Mango Lime Salsa

3 mangoes, diced

1 cucumber, chopped

2 Tbsp. red onion, chopped

2 Tbsp., or to taste, fresh cilantro chopped

1 small jalapeño pepper, chopped (optional); pinch of red pepper flakes (optional)

juice of 1 lime

1 Tbsp. olive oil


Mix all together with salt an pepper to taste, and let sit at room temperature to get acquainted for an hour before serving.