A Golden Moment in a Northern California Garden

“Focal point” doesn’t adequately describe the arched walkway of golden chain trees in Sandra Rennie’s Philo, California garden. “Event” is much more fitting.

During a visit to the garden one cloudless day last May, I enjoyed the privilege of strolling underneath the fortress created by forty carefully trained trees of Laburnum ×watereri ‘Vossii’. Beneath its dense, thriving roof of signature neon-yellow flowers, I felt as if I were staring at an endless ceiling of delicately jeweled chandeliers.

“If we have a gray day, and you walk under this feature while it’s in bloom, it’s like the sun is shining,” said Rennie, a self-taught gardener and retired environmental mediator. “It’s so yellow, so beautiful, and the bees go wild over it. Just stand under it, and you’ll notice the whole thing is shaking from the bees. They’re so excited to get to the pollen.”

The idea to build the arbor had been abuzz in Rennie’s mind ever since she’d seen a 1990 calendar photograph of a Laburnum arch from Bodnant Garden in Wales. “I’d never grown or seen a Laburnum tree in growth, but I looked at this picture, studied it, and estimated how far apart the trees were planted and the width of the space, and said ‘I can do that.’ ”

Rennie and her husband, Nicholas Yost, an environmental lawyer, planted the Laburnum trees (shipped bare-root by Bloomer’s Nursery in Eugene, Oregon) in February 1998 and hired a local ironmonger, Danny Piffero of Mendocino Metals in Ukiah, to custom-design the arbor’s vast metal framework. At the time, the couple was having a Mediterranean-style home built on the same plot and had set up temporary living quarters in “an old, beat-up mobile home” nearby until construction was complete. “It had been raining a lot. The ground was fully saturated, almost to the point of liquefaction,” said Rennie. “And I got a call that the Laburnum trees were on their way.”

Eager to get the trees planted, Rennie and her husband devised a game plan. “We figured out how many trees we had to plant each day, and we wouldn’t stop until we reached our quota.” However, Mother Nature had thrown them a curve ball. “It was so wet and cold our fingers were stiff,” Rennie recalled with a laugh. “And my husband had gotten so muddy I had to squirt him off with the hose.”

Completing the Picture

It was a dirty job, but entirely worthwhile, yielding stunning results. The walkway is the centerpiece of a scene painted with color and texture—a skillful composition of ample dimensions and a vivid sequential experience. It is 105 feet long and 20 feet wide, measured across the path between opposing trees. A decomposed granite path lined with English lavender (Lavandula angustifolia) serves as a charming prelude to the entrance. There, one is welcomed by sweetly scented Iris pallida ‘Variegata’, planted along the path’s interior to echo the symmetry of the trees; their pale lavender blooms are a striking contrast to the pendulous yellow flowers dangling above.

Laburnum, a member of the pea family (Fabaceae), is a deciduous tree of upright growth, lovely olive bark, and bright green trifoliate leaves; it is best known for its sweet peashaped flowers that hang in long racemes, similar to those of wisteria. All parts of the tree are poisonous, especially the seedpods. ‘Vossii’, a sterile hybrid of L. alpinum and L. anagyroides, is the most commonly available and most widely grown; it reaches a height of fifteen to thirty feet and a spread of ten to twenty feet. Laburnum is native to the mountains of Southern Europe—a world away but with similar growing conditions to Rennie’s garden, which sits on a 4.5-acre plot with a southwestern exposure (USDA hardiness zone 9, Sunset zone 14-15); it overlooks the vineyards of champagne maker Roederer Estates, and is blessed with a panoramic view of Anderson Valley.

A Trip to Bodnant

A couple of years after planting the arbor, Rennie and her husband traveled to Great Britain to tour gardens. Bodnant was at the top of their list. The Bodnant Estate has been in the Pochin-McLaren family for over 130 years; Charles McLaren, the third Lord Aberconway, was chairman of the Royal Horticultural Society from 1961-1984. Rennie asked various gardeners there about how the Laburnum arch was pruned and got the same fruitless answer every time: “You’ll have to ask the head gardener. He’s the only one that can answer your question.” A persistent Rennie wandered past a barrier to the entrance of his office, where a startled albeit polite “gatekeeper” confronted her. “I guess I must have looked terribly disappointed, because she told me to write out my questions and that she would ‘see that he gets them and he will write to you.’ ”

So Rennie wrote: “When do you prune? Are there any tricks to the training? What are the methods and techniques that you use in the training?” She was delighted to receive the following reply, on Bodnant letterhead, signed by the head gardener, Martin R Puddle (whose father and grandfather also served as head gardeners at Bodnant):

We prune our Laburnum arch in January of each year, cutting out all dead or dying wood and one third (of the overall length of the arch) of the three-year-old stems right back to the main branch. The new growth is then pulled down and tied in with string, no closer than 1 1/2 inches apart to allow for light and air to permeate.

Care and Culture

Optimal growing conditions for Laburnum include moist, well-drained soil and afternoon shade if grown in hotter climates. It is hardy to USDA zone 5 and generally does not fare well in zones warmer than 7; Sunset recommends it for zones 1-10 and 14-17. Rennie’s walkway receives full sun all day long; she amended the existing clay soil to improve the drainage. A sophisticated drip irrigation system emits an estimated half-gallon of water per tree every week that the system is turned on, which usually begins at the end of April.

Rennie continues to heed Mr Puddle’s expert advice on matters of pruning, but she’s already implemented her own personal touch. “When those new little branches are still green in the first year, they’re incredibly flexible but you can’t get to a lot of them.” So she made a little tool to help simplify the task: a steel vineyard stake she bent at the end to form a hook. “I can extend my arm to twice its length with my tool, grab hold of a branch, slowly pull it toward me, and tie it into the framework.”

It takes her about two hours to prune each tree or about eighty hours of work each winter. “And that’s it,” she said. “We spend that much time pulling weeds out of much smaller areas.”

For anyone interested in creating a Laburnum structure, Rennie’s advice is simple. “Do it,” she said. “If you have the ability and patience to appreciate something that only gives its maximum reward for about three weeks per year, go for it, because it’s worth it.”