Native Options for Small Trees and Shrubs

By Laura Lovett, CNPS Marin Plant Sale Committee

What we plant in our landscapes determines what can live in our landscapes. When we imagine a pollinator garden, we usually think of flowering perennials, but it turns out that our trees and shrubs support a much vaster array of insects and other creatures. If you have a small garden, planting a tree or flowering shrub will boost its biodiversity the most.

Oak trees are the winning choice, supporting over 1200 other creatures including hundreds of pollinators, but most native trees are host to well over a hundred pollinators. Species such as alder, maple, cherry (Prunus family), dogwood and buckeye will also provide resources in your garden. Even a lowly Arroyo Willow (Salix lasiolepis) supports over 200 pollinators!

We may all wish that we could fit an oak tree in our yards, but most of us don’t have the space. With that in mind, we have gathered a group of smaller trees and some shrubs that can be pruned into small trees—all of which will thrive in a more limited space, and we are making them available through our fall sale. Consider the choices we will offer.

Arctostaphylos virgata or Marin manzanita is known from only about 20 occurrences in the forests and chaparral of Marin’s coastal hills. Arctostaphylos virgata gets at least 6 feet tall and is known to exceed 20 ft. in height, growing in sun or part shade at the coast. Its twisted branches are covered in deep red bark. The shiny green leaves are accented by dense clusters of urn-shaped white flowers, which are an important food source for bees in late winter. It produces red berries in fall. [limited quantities]

Aesculus californica, Buckeye. An essential habitat plant in our region, Buckeyes get 12–30 feet tall and are typically multi-trunked. They thrive in part shade or full sun and go dormant by late summer. Butterflies love the creamy-white to pale pink flower spikes. Big orange nuts (drupes) will remain on the branches in fall.

Ceanothus ‘Ray Hartman’, Ray Hartman Lilac, is an easy-to-grow evergreen shrub or small tree to 15–20 ft tall by 10–15 ft wide. Give it full sun or part shade. The plant has dark green, glossy leaves and intense-blue flowers that emerge in late winter to early spring. Stunning when in bloom and very attractive to birds, butterflies, bees and other insects. Prune early to start shaping into a tree form.

Cercis occidentalis or Western Redbud is best known for the spring show of bright pink flowers that emerge ahead of the heart-shaped leaves. It usually tops out at 10–20 ft tall but is slow growing. Give it sun or part shade, and no summer irrigation.

Cercocarpus betuloides, Mountain Mahogany, is a distinctive-looking evergreen shrub that provides visual interest all year, with small creamy yellow flowers followed by long fuzzy seed capsules. It has a tall, upright habit and a fast growth rate, generally reaching 8–12 ft tall. Because of the upright form, it is often used in narrow areas and as a hedge or privacy screen. It responds well to light or heavy pruning. Also used for restoration and bank stabilization.

Corylus cornuta, Hazelnut, is a handsome, open, multi-stemmed shrub. Usually grows 6–10 ft. tall, can get 15–18 ft. Winter deciduous with decorative dangling catkins in winter. Produces tasty nuts but the creatures will probably get them first. A wonderful understory species to include in a woodland garden.

Quercus durata, Leather Oak, is one of the smaller oaks that can work in a home garden. It usually stays under 15 feet, with small, dense, holly-like leaves. In the garden, this plant can tolerate garden soil as well as drought and clay-rich soils. However, it is best adapted to relatively dry, rocky, nutrient-poor soil. Without early pruning it may look more like a bush than a tree.

Rhododendron occidentale, or Western Azalea, is a much sought after and admired native deciduous shrub found in moist places and stream banks. It leafs out in the spring with bright green foliage on an open, airy framework 4–8 ft. or more tall and wide. Glorious displays of fragrant azalea flowers in dense terminal clusters appear in late spring. Needs decent light, such as the edge of a woodland, to bloom well. [limited quantities]

Sambucus nigra ssp. caerulea, or Blue Elderberry can grow to the size of a small tree, 10–15 ft tall or eventually larger if irrigated, but it is easily shaped with pruning and can be pruned to a single trunk. It does best in sun and well-drained moist, rich soil. Attractive, hardy, and easy to grow. Abundant clusters of blue berries provide food for birds or can be made into wine.

A couple more shrubs of note:

For those who would love to have coffeeberry in their gardens, but need them to top out below window height, we want to mention that we will be offering Frangula californica ‘Mounding Manchester,’ a low form coffeeberry that gets 3–4 feet tall and spreads to about 6 feet wide. It will accept full sun in somewhat cooler locations but enjoys a little shade in hotter regions. It has small cream flowers, which are extremely popular with bees, and juicy, purple fruits enjoyed by birds. A great way to include this valuable habitat plant in your garden when you don’t have room for the 12-foot varieties.

Garrya elliptica ‘Evie,’ Evie Coast Silktassel. This plant’s attractiveness and neat growing habit make it appealing as a landscape species. This selection is dioecious (male and female flowers on different plants) and the ‘Evie’ cultivar is a selected male flowering form with profuse 8–10 inch catkins. This cultivar of the native silktassel bush is more compact than the better known ‘James Roof.’ Evergreen, it grows 10 ft. or taller. Sun to part shade, good drainage. Winter is its showiest time when it is covered in silvery catkins.

The plant sale opens online on Thursday October 10, 2024 at 6 pm. It can be accessed from our website under the tab “Store.” Items that don’t sell out will be available for in-person purchase on Saturday October 19, 10:30 am to 1:30 pm in the parking lot of Bon Air Shopping Center in Greenbrae. We hope you can find room in your garden for some of these special choices!