In the British ambassador’s garden, hybrid tea roses bloom into December. The gardeners at the residence on Massachusetts Avenue NW raise the fussy roses organically, aided by the sunny, open position of the rose beds at the foot of the portico. (Linda Davidson/THE WASHINGTON POST)
Gardening columnist

The hermit thrush is a late-fall visitor to my garden, and if the neighborhood cats don’t get it, maybe one day I’ll hear its call, said to be a plaintive warble of passerine perfection.

I arrived home the other evening, in the drizzle, to find a newt perched on one of the pillars of the front door. It was the eastern redback salamander, and it seemed happy to let me pick it up and move it to a safe place.

The thrush might find the salamander just small enough to eat, but that wasn’t the most obvious link between them. Both creatures are drawn to a garden where pesticides and fertilizers are little used, especially synthetic ones.

The songbird could rustle around for grubs and worms spared insecticide sprays; the moist-skinned amphibian could slither through a lawn free of fertilizer salts or fungicides. These vertebrates are the obvious signs of a healthy garden, but the organic gardener knows too that the soil is rich in decaying matter and teeming with life. This biosphere is microbial and cannot be seen easily, but it can be felt. This is the joyful aspect of organic gardening that goes beyond the science. It just feels good to be the steward of healthy natural systems that, in turn, nourish our plants.

Another gardener feeling the love these days is John Sonnier, the horticulturist at the four-acre greenhouse, gardens and grounds of the British ambassador’s residence on Embassy Row.

Head gardener John Sonnier at the double-bin compost area. Each year, the four-acre garden generates 30 cubic yards of compost, which is returned to the soil. (Linda Davidson/THE WASHINGTON POST)

With the blessing of its current occupants, Ambassador Nigel Sheinwald and Lady Julia Sheinwald, Sonnier has initiated an aggressive organic regime in a landscape with features notoriously dependent on chemical help, including a sweeping lawn, a formal rose garden and a greenhouse stuffed with orchids. In the garden’s ecological guise, there are echoes here of Prince Charles’s impressive organic and holistic approach to gardening at Highgrove, which I have seen and admire.

In rebuilding the greenhouse range, Sonnier and his colleagues have installed a sub-patio cistern that stores up to 1,700 gallons of rainwater used to water plants. Spared the chemicals in tap water, plants have responded with “a huge growth spurt,” he said.

Solar tubes on the greenhouse roof heat the water. Inside, the orchid collection and other tender plants receive individual attention by gardeners and volunteers, who check them for such pests as scale, thrips and aphids. The insects are destroyed by hand, using soap or alcohol.

Viruses tend to spread in old, large orchid collections, but all the diseased plants were culled and new ones get the quarantine treatment.

Outside, the large, formal rose garden terraces are full of beds of hybrid teas, the classic roses for cutting but also the fussiest. Sonnier said the great architect Edwin Lutyens, who designed the neoclassical mansion, did the gardeners a favor by laying out the rose garden in an open, sunny location where the roses get good air circulation. This significantly reduces blackspot problems. Other maladies are addressed as or before they emerge. With approximately 400 rosebushes, it’s an approach that requires constant attention.

“It’s gardening the old-fashioned way, hand-pulling weeds, hoeing,” Sonnier said. It’s also labor-intensive. “We have a whole platoon of volunteers, and we weed the rose garden on a daily basis.”

With its many old trees, the residence garden generates huge quantities of leaves each autumn. They are blown down the sloping land and across the lawn to a far corner where the gardeners put them through a shredder and pile them up for the winter. In spring, the semi-decayed leafmold is spread on beds as a mulch.

For the organic gardener, the compost pile is the heart and soul of the enterprise, a place where you not only recycle plant waste but create a black gold that feeds the soil. Plants are healthier in compost-enriched soil, and they need fewer nutrients for vigorous growth. Sonnier has built a pair of adjoining three-sided wooden bins, each 16 feet long and 8 feet wide. One holds fresh waste, the other compost that is finishing. He uses a small tractor to turn the piles, as often as once a week in peak periods of spring and fall. “You couldn’t do this by hand. We produce 30 [cubic] yards annually.”

How can you tell an organic garden from one that is routinely sprayed? The lawn has clover and nutgrass, and it’s probably thinner in high summer than some folks would like. “In September, things start looking better,” said Sonnier. You perceive other things in the organic garden — like salamanders and the hermit thrush.

In the ambassador’s garden, Sonnier has noticed that coral bells and violas have seeded themselves in various nooks and crannies, something that preemergent weedkillers would have prevented before. He says he sees more bird life, more worms and certainly more hawks drawn to an abundance of prey. Free of pesticides, the grounds now feature a couple of beehives and a newly installed box, a condo for 600 bats.

Organic gardens require more involvement from the gardener, in observing and dealing with pests and disease and in building the soil. The default for many, in homes, offices and, presumably, even diplomatic outposts, is to use a landscape contractor to show up on a prescribed schedule to apply pesticides and fertilizers and to lay blankets of mulch two or three times a year. This saves a lot of hassle. but for a gardener like Sonnier it creates far greater burdens, such as the worry about the safety of the herbs, vegetables and fruit raised for the kitchen, or what’s on the flowers that are cut and placed in all the rooms of the residence.

“I just can’t see the benefit of gardening through chemicals,” he said.

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