march garden updates with ellyn shea

Go Back in Time with the Trees of 20th Street

March photo 1

An old proverb says, “The best time to plant a tree was 20 years ago.” Fortunately, someone took that to heart and planted trees with Friends of the Urban Forest on 20th Street back in 1987. Some of us were worrying about pimples and prom dates back then. Some of us weren’t even born.

They are glossy privets, (Ligustrum lucidum), native to China, Korea and Japan. Privets are usually thought of as shrubs but this species can reach a great size. The champion record-holder in California is located in Sacramento Capital Park; it’s 62 feet high with a slightly wider canopy spread of 65 feet. Its trunk is 107 inches around. By contrast, our little privets are about 1/3 of the champion size. But remember what they’ve been through.

March Photo 2

Can you believe the corner used to look like this? Ugh! (Photo courtesy of Google Street View)

These trees are survivors, growing in compacted, oxygen-poor soil with just a little square open to the rain. During the years of neglect while the building was vacant, the trees remained green. The initial installation of the sidewalk garden was probably a bit traumatic, disturbing roots, but the payoff was increased access to water and plants underneath shading and cooling the soil.

March photo 3

The leaves of privets and their relatives have opposite leaf arrangement; the leaves emerge in twin pairs

Surprisingly, privets are in the same botanical family as olive, ash and lilac. Privet flowers attract bees; on a sunny day you can sometimes hear the trees buzzing. Birds like the blue berries. Humans don’t tend to love these trees though; the flowers can be allergens, the berries are toxic to us, and the species can be invasive in certain ecosystems. (Thankfully, 20th Street is not one of them.)

March photo 4

There are 3 birdhouses in the older privet trees; 2 on Alabama Street and one outside of Sightglass Coffee. Keep an eye out this spring for nesters…

Although they may not be perfect, studies show that having street trees is better than not, for many reasons. Trees store carbon dioxide and release oxygen, intercept stormwater and provide bird habitat. They’re also good for business. According to a study by the University of Washington, consumers in a business district spend more time and are willing to pay higher prices when there are trees and greenery around. (Come for the food and wine; stay for the trees.) The presence of trees has been shown to reduce crime and calm drivers. (sadly, fights over parking spaces are still alive and well).

March photo 5

Intersection of 20th and York in 1929 (courtesy of the San Francisco Public Library

March Photo 6

The same intersection, Google Street View.

Put it this way; we evolved from forest-dwelling creatures, and we are still hard-wired to feel better being around and looking at trees. We’ll pay more for a home surrounded by trees, even if we groan about the cost of tree maintenance. We want to live in neighborhoods with access to green space, and we pass laws protecting public trees. We simply don’t feel good surrounded only by concrete, and that’s why this city – and this neighborhood – is becoming greener.

March photo 7

Although the best time to plant a tree was 20 years ago, the second best time is now. Plant a street tree in the Mission with Friends of the Urban Forest on April 5th, 2014. Property owners, you’ve got til March 6th to sign up.

Ellyn Shea is a Bay-Friendly gardener and garden coach in San Francisco.

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