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Pruning California Native Plants

Due to recent droughts there is an increased interest in California native plants. What are native plants? For the purists, it is only those plants that grow within their own watershed. For others this expands to encompass the Bay Area, perhaps the central coast, or the whole of California. Natives have been admired in the wild but garden use is fairly new and we have a lot to learn about their cultivation. To quote Michael Alliger, a highly regarded, local, aesthetic pruner, “Please continue exploring and experimenting with woody natives. No one but us will discover their true viability in the garden!”

There are many reasons to plant natives in the garden. Native plants are suited to our climate and ecology. Natives are drought tolerant, heat and frost resistant and low maintenance (no fertilizer, little dead-heading, and usually little pruning). They provide habitat for local birds, bees, insects and mammals as the plants have co-evolved with local wildlife. Robins and cedar waxwings eat toyon berries. Monarch butterflies lay their eggs on milkweed. Native plants provide acorns for woodpeckers and scrub jays, native flowers for hummingbirds and native bees, and elderberries for the birds.

Native plants are attractive and provide seasonal interest, such as white sage, Garrya with silk tassels, Toyon with winter berries, spring flowers of currants and ceanothus, and white Manzanita bells at Christmas.

For planting, dig a hole only as deep as the root ball but twice as wide. Lightly amend the soil if it is heavy clay and disturb the roots as little as possible. Best time to plant is fall, and plants will need watering once or twice a month through the first two summers. Fall is also a good time to prune natives.

Basic pruning
Most of our gardening knowledge comes from Northern Europe and the East Coast, including how to prune. Most pruning rules that apply to non-native plants also apply to native plants. However, due to our Mediterranean climate, we experience two dormant seasons and two springs. In summer native plants are mostly dormant due to high temperatures and lack of rain. Our first spring usually starts in October when temperatures cool and the first rains arrive. Grass sprouts, leaf and flower buds begin to emerge from summer dormancy. Growth slows down in winter when days shorten and temperatures drop. Our second spring usually begins in late February when days lengthen and temperatures warm up.

In Japanese gardens around the world, the plants used are 90% Japanese natives. The Japanese aesthetic pruners attempt to replicate nature. How do you wish to style your trees and shrubs? You can enhance the natural growth of the plant and highlight its essential beauty such as the structure of the branches or blooms. You can shear manzanitas, layer oaks like Japanese maples or bonsai-like salvias. The choice is yours.

There are three basic cuts used for pruning both native and non-native plants:

  • Thinning cut (removes a branch back to its point of origin). This is used to improve structure, let in air and light. Do not leave stubs or do a flush cut. Cut just outside of the branch collar.
  • Heading cut (cutting back newest growth to a bud, leaf or small twig). Used to promote density of leaves, fruit or flowers, and to reduce size. Also called tipping or shearing if carried to extreme!
  • Re-leadering cut (removal of leading branch by cutting to a side branch which will then become the new leader). Used to reduce size of plant.

Also, keep in mind a few pruning tips:

  • Dead, dying, and damaged branches can be removed at any time.
  • Clean out branch unions (where to branches come together).
  • Remove suckers from root crown, unless you are trying to renovate a plant or encourage multiple trunks.
  • Remove only up to 1/3 of plant at a time.
  • Become aware of how freely the plant back-buds (sprouts from old wood).

Here are guidelines for specific California natives:

Deciduous Plants:

  • Generally prune in late winter before they leaf out.
  • Creek Dogwood (riparian plant): Could be cut back or coppiced i.e. cut almost to the ground (or just shaped!) in winter; new twig growth will be red.
  • Prune Elderberry: Prune as a small tree or cut back to create a dense shrub for more blossoms and fruit.
  • Western Redbud: Can be pruned as a multi-trunked tree or shrub or can be trained with a single trunk. Prune after flowering. Or in late winter thin out old trunks or coppice to rejuvenate.

Broadleaf Evergreens:

  • This includes most of our local plants such as oaks, bays, toyon, ceanothus and madrone. Prune in late summer when dormant, before the rains.
  • Ceanothus: Prune lightly as these rarely produce shoots from old wood. Recommend tip pruning, and thinning of interior and low dead growth.
  • Toyon: Shape prune in late summer even though you are cutting off the berries! Early Spring is also an option. Toyon is susceptible to fire blight, which should be removed as soon as noticed.
  • Manzanita: Prune lightly as it does not back bud. Showcase the beautiful trunk and deep red bark with judicious thinning cuts. Leave a stub (you can remove some later). Consider leaving dead branches for character.

Woody Shrubs:

  • Lightly prune throughout the year to keep compact and full. Or, remove 1/3 of plant after flowering to shape and control size. Some can be coppiced.
  • Bush Anemone: Prune back 1/3 after flowering to improve shape. Or cut back hard in late summer to encourage fresh growth.
  • Coffee Berry: This is a very adaptable plant which is handsome year-round. Prune in late summer for structure.

Herbaceous Perennials:
These include Romneya, California fuchsia and some salvias. Cut back by one third, or a few inches above the ground in late winter before new growth.

Get started with a few natives and have fun experimenting!

- Linda Oquist

Native Plant Resources

Native Plant Nurseries
- CNPS sale at Falkirk Mansion in San Rafael (April/October)
- https://www.cnpsmarin.org/native-plants/resources/item/277-native-plant-nurseries
- https://www.marincounty.org/depts/pw/divisions/creeks-bay-and-flood/mcstoppp/nurseries

Helpful Websites
- https://www.cnps.org/gardening
- http://calscape.org/planting-guide.php

Botanical Gardens/Tours
- http://www.ebparks.org/parks/tilden/botanic_garden.htm
- https://www.sfbotanicalgarden.org/garden/go-native-2012.html