November Garden Update: Urban Habitat Gardening: A Study in Compromise

Urban Habitat Gardening: A Study in Compromise

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We are not alone on this planet. Humans share the world with a dizzying variety of animals, plants and other organisms. This didn’t happen by accident; species co-evolved to depend on each other for food, shelter and reproduction. We wouldn’t live long without plants and the oxygen they create. Plants wouldn’t live long without insects to pollinate them and fungi to optimize their roots.

We need to do what we can to support a diversity of critters not only because they are interesting in their own right, but because each has its role. As the world becomes more urbanized, our small gardens and open spaces become much more important to the non-human species. However, the urban environment places some limitations on what we can do.

Here are several tips to make your garden a little more wildlife friendly, along with some possible modifications:

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1. Plant a layered garden. As much as possible, include a variety of plant heights in your garden: ground covers, small perennials, medium and larger trees and shrubs. This allows habitat niches for a variety of birds and insects. 20th Street and Alabama Street have good height diversity; it will take a while for Florida Street’s trees to get big enough. Trees need room to grow, so if space is limited, consider adding a birdhouse, bat house or insect hotel to an outside wall instead.

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(Where trees are not dense enough, or there’s no room for trees, a birdhouse can provide shelter)

2. Provide some density. Birds and insects like a place to be sheltered. On 20th Street, some shrubs and plant groups are kept somewhat dense. In your backyard, a small brush pile or even a rock can provide a home or a place to rest.

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3. Flowers and Fruit: Choose plants that flower to provide nectar and pollen to insects and birds. Bees practice flower constancy, meaning they visit the same kind of plants on a given outing. Therefore, densely plant a patch of the same kind of plant – at least 3 square feet – rather than one each of different kinds. Choose a palette of plants that will bloom at different times of year so there is always something to eat. Aim for 50% of the species to be native plants to support native bees. To learn more about native bees and their preferred plants, visit

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When flowers fade, let the seeds and fruit develop to feed birds, rather than “deadheading” or removing spent flowers. If aesthetics are important, consider deadheading only in important visible areas and allow seeds and fruit in more out-of-the-way spots. Generally we keep things a little neater towards the corner of 20th and Florida, and leave more seedheads on towards the west end of the block.

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4. Soil is a habitat too: Many insects live in the leaf litter below trees, eating dead wood and leaves and contributing to the health of the soil. Keep your organic matter on site by sweeping leaves off paths and into garden beds – then leave them there. Adding compost and mulch on top of soil is also a good way to save water, suppress weeds and feed soil organisms that enrich the soil for plants.

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However, I was amazed to learn recently that 60-70% of native bees nest in the ground and require bare, unmulched soil! The University of California Urban Bee Lab asks gardeners to keep some soil bare – up to 50% of the garden – to support native bees. This presents a conundrum for gardeners. We are constantly advised to cover soil with organic matter – with good reason.

There is exposed soil on 20th Street in front of Central Kitchen/Salumeria. I wonder if some compost and mulch would help these sun-baked plants and soil – or would that take homes away from native bees? Then I wonder if bees would even be able to nest in such compacted, rooty soil. When planting here, it’s hard to dig a hole for even a small plant. I have written an email to the team at for advice. Perhaps I will have an answer in a future article.

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5. Provide some water. Birds like a dish of water with somewhere to perch. A large saucer like those used under potted plants with a rock in the middle can attract birds to bathe and drink. A few inches of water is too deep for bees and butterflies, who prefer mud puddles. A simple insect puddler can be made following these instructions. On 20th Street, leftover ice from the kitchen and various events is left to melt in the garden, hydrating plants and creating mud for insects.

Finally, take a moment to sit down and observe the birds and insects doing their thing in your garden, park or local open space. Or get an inexpensive macro lens for your phone camera and see the artistry in a bee’s wing.

More resources:
The Habitat Garden Book by Nancy Bauer
Nature in the City
Pollinator Partnership
Xerces Society

Ellyn Shea is a gardener and consultant in San Francisco. Visit her at

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