Edited by David Mizejewski, National Wildlife Federation Naturalist
When we picture a vibrant garden, our minds often jump to colorful swaths of annuals and perennials. But the true backbone of the garden, the steadfast workhorse that provides year-round structure, wildlife support, and multi-season interest, is often the humble shrub.
It’s a common misconception that 'shrub' defines a specific type of plant; in reality, it's simply a woody plant with multiple stems, a growth pattern that offers a wealth of benefits that make shrubs indispensable in any garden, regardless of size.
Unlike their herbaceous counterparts that die back in the winter, shrubs provide essential year-round cover and structure for wildlife. Their dense, woody framework offers protection from the elements and creates safe havens for nesting and raising young. You can easily picture birds building their nests in the branches, or butterflies and moths finding a secure spot to pupate.
This vital support extends across the seasons. Many shrubs kick off the growing season with showy, fragrant blooms, providing crucial nectar and pollen for a variety of insects. For some, this relationship is highly specialized. For example, the Andrena mining bee relies almost exclusively on blueberries (genus Vaccinium) and other plants in the heath family. This partnership is essential because blueberries require "buzz pollination," a unique process where the bee vibrates its flight muscles to release pollen. In return, the Andrena bee has evolved a longer face to reach this pollen, demonstrating a perfect co-evolutionary partnership.
As the year progresses, this appeal continues. Some shrub species flower in the summer and into the fall. No matter when they bloom, the flowers give way to berries, offering a critical food source for birds and mammals. Many shrubs, particularly in regions like the northern US, put on a spectacular display of great fall color, with sumacs blazing in brilliant scarlet and blueberries and huckleberries painting the landscape in fiery hues. This multi-season appeal ensures your garden remains a beautiful, dynamic, living ecosystem all year long.
The versatility of shrubs is a major advantage. Whether you have a sun-drenched border, a shady corner, or challenging soil, there’s likely a shrub that will thrive. This adaptability makes them ideal for filling various niches in your landscape design.
Nature, of course, rarely adheres strictly to our neat categories. The definition of a shrub versus a tree can often be a matter of growth pattern rather than a strict classification. For instance, plants like Allegheny Serviceberry (Amelanchier laevis) are often classified as small trees but can exhibit a multi-stemmed, shrub-like form, providing year-round beauty and essential food for wildlife. In early spring, this plant bursts into bloom with delicate white flowers that attract pollinators, while its summer berries offer a nutritious food source for birds and mammals.
Another excellent example is Common Elderberry (Sambucus canadensis). This fast-growing plant provides dual-purpose benefits, with its showy, flat-topped flowers attracting a wide array of pollinators. These blooms give way to clusters of purple-black berries that are a key food source for birds and can be used to make jellies and wines. Native bees nest in their pithy stems. Elderberry beautifully demonstrates how a "shrub" can grow quite large, further blurring the line between shrub and tree.
Similarly, while we often refer to palm "trees," their growth pattern is more akin to grasses, growing in segments rather than in the rings of a true tree. Cacti, too, follow a distinct growth pattern that sets them apart from both shrubs and trees, even when they take on a singular, tree-like form.
To further complicate matters, some herbaceous perennials, like Orange Butterfly Milkweed (Asclepias tuberosa), can have a "shrubby" growth habit. Though it dies back to the ground in winter, its multi-stemmed, bushy form during the growing season functions similarly to a small shrub, providing crucial structure and acting as a host plant for monarch butterfly caterpillars. This shows how nature often blurs our neat categories, with plants of different types fulfilling similar roles in the garden ecosystem.
Both shrubs and trees are some of the most vital host plants for various insects, including butterflies and moths. Think of mighty oak trees (genus Quercus), for example. This genus supports over 550 species of caterpillars as a host plant —a staggering testament to its ecological value.
The benefits we've discussed for shrubs apply equally to trees if not more so. Trees provide vital vertical habitat by creating distinct layers: the canopy, the understory, and the ground layer. While a large canopy tree provides immense value, a truly biodiverse wildlife habitat creates a layered environment that offers food, cover, and nesting sites at multiple elevations.
Shrubs are the essential component of this understory layer, bridging the gap between towering trees and low-growing wildflowers. They provide that critical middle ground, offering protection for birds and small mammals, acting as a windbreak, and providing a different set of food resources for pollinators and other wildlife.
Consider these examples of native shrubs that are perfect for establishing this mid-level habitat:
Arrowwood Viburnum (Viburnum dentatum): A versatile and hardy shrub, Arrowwood Viburnum offers multi-season interest. In spring, its flat-topped clusters of white flowers attract a wide array of pollinators. It’s the caterpillar host plant for spring azure butterflies. The blooms are followed by beautiful blue-black berries in the fall that are a favorite food source for birds, providing a vital resource for migrating species. The shrub's dense, branching structure also offers excellent nesting sites.
You can transform your garden from a two-dimensional space into a dynamic, multi-level habitat that supports a richer diversity of life by adding these and other native shrubs to your landscape.
Stepping down in size, we encounter subshrubs, also known as woody perennials or suffrutescent plants. These are low-growing plants with woody bases and herbaceous upper growth that may die back partially or completely in colder months. They offer a unique blend of the resilience of woody plants with the floral display of perennials, making them valuable additions to various garden settings, especially in drier climates.
California boasts a stunning array of native subshrubs perfectly adapted to its diverse ecosystems. Incorporating these into your garden not only adds beauty and fragrance but also provides essential habitat and food sources for local wildlife.
Let's explore a few examples:
White Sage (Salvia apiana): This iconic California native is prized for its silvery-white foliage and fragrant flower spikes that attract bees and other pollinators. It thrives in sunny, dry conditions and is also culturally significant for its traditional uses.
Coyote Mint (Monardella villosa): With its whorls of fuzzy, gray-green leaves and clusters of pink to purple flowers, Coyote Mint is a charming and resilient subshrub. It's a favorite of native bees and butterflies and releases a minty fragrance when crushed.
Bush Monkeyflower (Diplacus aurantiacus): Known for its vibrant orange, tubular flowers, the Bush Monkeyflower is a hummingbird magnet. It thrives in sunny to partially shaded, well-drained conditions.
By now, you've seen that a shrub is so much more than a “plant type.” It's a growth pattern that provides the year-round structure, cover, and food sources that make a garden truly resilient and teeming with life. From dense cover for nesting birds to vital pollen for specialist bees and the mid-level habitat that bridges the gap between trees and flowers, shrubs are the workhorses of your wildlife garden.
Ready to unlock your garden's full potential? Explore our selection of native shrubs and other pollinator-friendly plants at gardenforwildlife.com.