Greenhouses for Plants and People

These glass houses shelter people as well as exotic blooms

For the first time this January, Charles L. and Joan Blanksteen soaked in their steamy hydrotherapy pool while gazing at the deep banks of snow around them. Separating the Blanksteens and their pool from the freezing weather was a 616-square-foot, all-glass structure with slate floors and space for a dining table that can seat 20. Soon, they will be sharing the space with a small jungle of orchids and fresh herbs.

Construction on the Blanksteens’ luxurious greenhouse, which adjoins their 18th-century home on 17 acres in Millbrook, N.Y., began in August and is nearly done. “Halfway through, my wife joked we should call it ‘Charlie’s folly,'” says Mr. Blanksteen, because of waterproofing challenges and delays. So far the costs have totaled about $250,000; the couple plans to begin displaying plants in it in a few months.

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To move this 1937 greenhouse from a property in Woodside, Calif., to a Napa Valley vineyard, a team disassembled, moved, sandblasted, repainted and then reassembled the structure. Drew Kelly for The Wall Street Journal

The first greenhouses were built by the ancient Romans. In Victorian England, possessing a room where citrus trees could bloom midwinter was a luxury that few but the Downton Abbey set could afford. Hobby greenhouses enjoyed a boom in the U.S. a few decades ago, but as middle-class homeowners have struggled in recent years, the industry has contracted.

Now, greenhouses are returning as a feature of luxury homes. And many of today’s greenhouses aren’t just for plants. They’re highly personal “green rooms” for reading, dining and entertaining as well.

“We used to sell a lot of greenhouses to the average homeowner, but over the last 40 years, that has changed,” says William Orange, president of High Falls, N.Y.-based Under Glass Manufacturing. “It’s only people with a lot of money who are building greenhouses.” While a hobby greenhouse starts at under $15,000, Mr. Orange says his company’s average project is a custom greenhouse costing closer to $100,000.

James F. Zoppo, a 66-year-old horticulturalist, added a custom Victorian-style conservatory to his home in Sharon, Mass. Over the past year, he and his wife, Sharon, have also built a 4,000-square-foot commercial greenhouse for their collection of exotic plants. For the personal “green room” attached to their home, the Zoppos added a wood-burning stove to keep their dining guests toasty in the event of a power outage.

Mr. Zoppo compares adding a conservatory to adding a wine cellar, calling it a lifestyle and an aesthetic decision. “I’ve tried vacations, but they don’t work as well for me as days in the greenhouse,” he says, explaining that he often spends his days in his greenhouse and his nights in his conservatory. The conservatory cost about $100,000; the greenhouse will cost about $200,000 when it is done.

When guests enter the greenhouse of the Oakville Ranch in Napa Valley, they step into a formal palm room featuring Phoenix roebelenii(pygmy date palms) flanking the table where visitors sometimes enjoy a glass of wine. The wing to the right contains the orchid collection. To the left is the “tropical room,” with a koi pond and a ceramic fountain. The ferns and succulents are “a collection that would make Dr. Seuss feel right at home,” explains the room’s designer, San Francisco-based Dat Pham. The greenhouse belongs to Mary Miner, who is the owner of the Oakville Ranch, according to the ranch’s website and employees of the ranch.

“It’s like a chandelier at night when it’s lit up,” says Gary Brandl, who was Mrs. Miner’s contractor for the project.

Mr. Brandl recounts the greenhouse’s unusual history: In the spring of 1996, he says, Oracle co-founder Larry Ellison reached out to Mrs. Miner, the wife of the late Oracle co-founder, Robert N. Miner, with a proposal. Knowing she was a plant lover from England, Mr. Ellison offered to give Mrs. Miner the 1937 greenhouse on a property he had purchased in Woodside, Calif.—as long as she would arrange to move it before its scheduled demolition date.

Mr. Brandl went to take a look. The greenhouse had been manufactured by Lord & Burnham, the American manufacturer behind New York Botanical Garden’s Haupt Conservatory, San Francisco’s Conservatory of Flowers and many notable residential greenhouses. While much of its original glass was gone, the superstructure of steel, cast iron, and cypress “ribs,” as well as the delicate cast-iron fleur de lys, were intact.

Numbering each of the hundreds of pieces, Mr. Brandl’s team disassembled, moved, sandblasted, repainted and then reassembled the structure at her 350-acre Oakville Ranch, whose vineyards produce wine and overlook the Napa Valley. According to Mr. Brandl, Mrs. Miner wanted to locate the greenhouse near the estate’s gated entrance.

The problem was that the ideal spot for it was, at that time, a steep gorge. So, Mr. Brandl and his crew terraced the drop-off and created a level site for the roughly 1,200-square foot structure, which has a center room and two wings. Overall, the project took about a year and cost $250,000 to complete, Mr. Brandl says. Now, the Oakville Ranch’s greenhouse is one of the estate’s centerpieces. (Mr. Ellison’s spokesperson said she isn’t familiar with the greenhouse. Mrs. Miner declined to comment.)

Anglophilia led to Thomas Bertelsen’s decision to build a conservatory and greenhouse onto his home in Ross, Calif. Mr. Bertelsen, 74, a financial executive, was traveling frequently to London for business and was charmed by the traditional British conservatories he saw there.

Mr. Bertelsen and his wife, Sandra, added a conservatory with a dining area off their kitchen, with an internal door leading to a greenhouse filled with succulents. The two rooms have different climate zones, and both have radiant heating. Altogether, he estimates the project cost about $500,000 when it was completed about 15 years ago. Mr. Bertelsen, whose favorite plant in his collection is the Agave attenuate “variegata” (or variegated fox tail agave), likes to listen to Bach while reading in the conservatory.

To house their plants, and themselves, Esther and Brian Dormer built a pair of 400-square-foot greenhouses on their 150-acre farm in Bulger, Pa. One is a traditional greenhouse where they grow lettuces, flowers and herbs. “It smells really fragrant in there,” Mrs. Dormer says. The other is used an indoor/outdoor reading room from the spring through the late fall, and it features an iron bird from Africa, cherub lights and other whimsical touches. In that room, they also house hardier evergreen plants. Built around eight to 10 years ago, the greenhouses are insured for $200,000 each.