For any gardener, high summer is quiet compared to spring or fall. But while it may not be a time for ambitious planting projects or heavy cleanup, it is a time for ongoing maintenance — especially chores that pay off long-term.

At public gardens such as Untermyer Park and Gardens in Yonkers, New York, a 43-acre former estate on the Hudson River, it was an eerily quiet spring and early summer without visitors, even before the “summer pause,” as Timothy Tilghman, the head gardener calls it. But there is still work to be done.

“Patrons elevate the standards,” Tilghman said, but even without them, “a public garden should always be display-worthy.” He keeps his eye on his list of tasks, reshuffling them as priorities and staffing levels shift.

The lockdown did allow a little cheating: The crew left sprinklers and hoses out between waterings of the 2,000 newly planted perennials, rather than dragging them back into storage daily, as they would in a normal year.

But in other ways, the public’s absence got back at the gardeners by creating additional tasks: “We never have to weed our paths, because usually visitors walk on them,” Tilghman said. “But this year, no feet.”

As August beckons, Tilghman shared his high-summer to-do list.

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Water and weed consistently

“If you can’t enjoy weeding, you won’t be a happy gardener,” said Tilghman, citing its importance to a garden’s health and visuals. “Everyone enjoys the neatness of a fresh planting, but unless you’re willing and eager to get in there and weed …”

Deep, diligent watering, like weeding, is also crucial.

And while you’re tending to both: Observe and make note of what needs fixing.

“We look for scale, vigor, composition — and aesthetic worthiness,” Tilghman said. “Does a plant look good in the border, and is it worth growing?”

Sometimes what was irresistible in a catalog isn’t as appealing in your garden. “Once established, maybe it doesn’t add a strong visual element, or it’s too compact — or colonizes when you didn’t expect it to,” he said.

At Untermyer, those insights become essential fodder for action plans in the fall and the following spring.

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Prune and deadhead spent roses and other flowering perennials. (Getty Images)
Prune and deadhead spent roses and other flowering perennials. (Getty Images)

Deadhead and groom

Untermyer’s lavish annual and tropical schemes in beds and pots are deadheaded regularly and pinched back for scale. But not just the annuals.

Some shrubs, including messy-looking spent roses and even certain hydrangeas, also need grooming.

“While most hydrangeas look great through winter, some don’t,” Tilghman said. “The arborescens flowers that won’t look good dry and tawny, and pull the plant down into a flattened mess — they get deadheaded, too,” along with any floppy blue mopheads or macrophyllas.

“We’d rather have nice green shrubs,” he said. “Thankfully, the oakleaf types, you usually don’t have to touch.”

Plan to save seeds

Some annuals self-sow if they are allowed to set seeds — including nicotiana, verbena bonariensis and annual poppies. So don’t deadhead every last fading flower as late summer approaches.

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“When I go into a nursery and there’s a flat of 12 seedlings at $5 a plant, I just can’t buy it,” Tilghman said. “With the really prolific self-sowers, it’s much more economical to gather seed this summer and fall — or just plan to leave plants in place to sow themselves.”

Clean edging will make any garden look better. (Getty Images)
Clean edging will make any garden look better. (Getty Images)

Don’t forget to edge

Attention to detail was instilled in Tilghman when he worked for Marco Polo Stufano, the founding director of horticulture at Wave Hill, a public garden not far down the Hudson, in the Bronx.

“A secret: You can make your garden look pretty good, no matter what’s really going on,” he said, “as long as path and bed edges are crisp and weed-free. Marco used to remind us that ‘God is in the edges.’ ”

Mulch around trees (correctly)

A ring of mulch right out to the drip line is better for a tree than ground cover or even grass, which compete for moisture and nutrients.

Untermyer’s two most important trees, old weeping beeches, had been underplanted with pachysandra, which Tilghman removed in favor of mulch. But just 2 or 3 inches, no deeper — never the dreaded “volcano mulch” — and never mulch against the trunk, where it can harm the bark and invite decline.

“If you do have ground cover growing around trees,” he said, “this is a good time to edit and get it 6 to 12 inches away from the trunk, like the mulch.” Rodents love to tuck in and gnaw on bark, especially in winter.

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Look to simplify

For all Untermyer’s artful plant combinations, sometimes simplicity is preferable. Are there places in your garden that need quieting?

The Vista, one the garden’s most important Hudson views, is embellished by ancient Roman columns installed by the long-ago property owner, Samuel Untermyer, and beyond that, by the river and rugged Palisades.

The team created an allée of 99 cryptomeria and, beneath them, twin stretches of golden Japanese forest grass (Hakonechloa macra Aureola). Both plants have year-round appeal and neither distracts from the real show. Instead, they frame it.

“On any main axis or transition moment within a smaller garden, or anywhere you have a bigger view,” Tilghman said, “an overly fussy planting can actually compete and add visual static. Let the big moment nearby show.”