Although Bell suggests pruning trees about every three years, these soon grew to be 15 feet tall.
The front didn't fare much better.
Bell succumbed to the temptation to plant a large Chinese elm to fill in an empty corner.
"I don't usually plant them for others unless they have more room," she said, but soon the huge tree kept the sun from roses and grass.
"It was dominating. I fell into the trap of 'I want something big now,' which I watch with other people. I'm cautious with clients to talk about the future.
"I didn't listen to my own advice," she said.
Ten years later, she's listening — and removing the biggest offenders: the pair of pear trees and the Chinese elm, as well as a couple of other smaller trees in back.
Over the years, Bell has added a small deck and pavers under an outdoor dining table and chairs in the narrow back yard. She's decided to keep most of what she planted 10 years ago, including her Chinese Snowball viburnum.
"Everything else I made smaller and more open underneath," she said.
Assessing a mature garden involves more than looking at plants inside one's yard. One's neighbors' plantings can have a huge impact on shade, and on how well things thrive or don't on your side of the fence.
But as time passes, the neighbor's oak began to dominate a corner of Bell's backyard.
"I never noticed the oak, but now I'm cutting back the pittosporum under it," she said.
She's keeping her own cork oak in an opposite corner, now soaring more than 30 feet tall. "It's a wonderful tree, not as sensitive to water," she said.
Most of her sun-seeking plants are thriving in pots, with a drip system delivering water to the tomatoes, cucumbers, herbs, lime and lemons. "Next year I'll do more," she added.
She even encourages "what some would call invasive things," she said, pointing to a purple mass of tricillium. "It keeps changing, and I like that."
Bell, who owns her own landscaping firm, Janet Bell & Associates, Menlo Park, is known for planting for year-round color.
"My big thing is flowers all year," she said, pointing to last summer's salvia, roses, yarrow and tricillium. In fall, the aconitum (from the buttercup family) will be blooming. In winter, she'll cut things back as they go dormant, readying her yard for a spring showing of dogwood, flowering cherries, snowballs and many varieties of true geraniums.
Her favorites are scented, with names like Chocolate Candy, ginger and Johnson's Blue.
She's also fond of the pair of climbing Sally Holmes roses that flank her front gate.
Now that the huge Chinese elm is gone, Bell has planted a cotinus Royal Purple.
"In winter, it's very open, but you're not in the garden between November and March. Why not let the sun in and have plants with great flowers?" she said.
Bell has planted a narrow strip between her home and her neighbor's with a rhododendron, camellias, wisteria and garrya elliptica, which creates an effective screen.
"People have to realize their plants are living things. It's won't look the same in five or 10 years. Be ready to do some changes," she said.
As for that Chinese elm, she said: "It was a really pretty tree but just not in the right spot."
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