Berberis thunbergii (Japanese Barberry)

Why is Japanese Barberry Considered Invasive?

Japanese Barberry (Berberis thunbergii) is considered invasive in many parts of North America and Europe due to a number of characteristics that enable it to outcompete native vegetation:

Hardiness and Adaptability: This plant is highly adaptable and can grow in a range of soil types and light conditions, from full sun to deep shade. This makes it capable of colonizing a variety of habitats.

Reproductive Success: Japanese Barberry produces a large number of berries each season, each containing seeds. These seeds are dispersed by birds and other wildlife, leading to the spread of the plant over large areas. Seeds have a germination rate of about 90%.

Lack of Natural Predators: In regions outside of its native range, there are few pests or diseases that significantly hinder its growth. Its thorny branches also deter browsing by deer and other herbivores, allowing it to thrive while other, more palatable plants are eaten.

Early Leaf Out: The plant begins leaf growth earlier in the spring than many native species, which allows it to photosynthesize and grow for a longer period of time. This gives it a competitive advantage over native plants.

Alteration of Soil Chemistry: Japanese Barberry is also known to alter soil chemistry by changing the pH, which can make the environment more hospitable for its own growth while being detrimental to native species.

Because of these traits, once established, Japanese Barberry can form dense stands that crowd out native plants and disrupt ecosystems, leading to decreases in biodiversity. This has led to its classification as an invasive species in several regions, and why its planting is discouraged or even illegal in some areas.

Garden Design with Japanese Barberry

Japanese Barberry’s vibrant foliage color, compact growth habit, and year-round interest make it a versatile addition to many types of garden designs. Here are some ideas:

Hedge or Border: Japanese Barberry is commonly used for hedges or low borders due to its dense, compact growth habit and tolerance for heavy pruning. It can create a vibrant, living fence that adds color and texture to your landscape.

Foundation Plantings: Due to its tolerance for various conditions and compact size, it makes for excellent foundation plantings around homes or buildings.

Mixed Shrub Border: Combine Japanese Barberry with other shrubs in a mixed border for variety. Its bright foliage contrasts well with green or blue-toned plants. It pairs beautifully with spirea, hydrangea, or boxwood.

Rock Gardens: In a rock garden, Japanese Barberry’s drought tolerance and vibrant foliage can provide a striking contrast with the stone elements.

Wildlife Attraction: Although the berries are toxic to humans, they are an excellent food source for birds. Consider planting Japanese Barberry near bird feeders or birdbaths to provide a safe, thorny refuge for small birds.

Fall Interest: Plant Japanese Barberry in spots where you want to emphasize fall color. The leaves turn from their summer colors (usually red, purple, or golden, depending on the variety) to a vibrant mix of orange, yellow, and red in the fall.

Container Gardens: Dwarf varieties of Japanese Barberry work well in containers for a pop of color on your patio or deck.

Remember, before planting Japanese Barberry, check if it’s considered invasive in your area and consider native or non-invasive alternatives if it is. Always try to maintain responsible gardening practices.

Companion Plants

Japanese Barberry is a versatile plant that can work well with a variety of companions in a garden. Here are some good companion plants for it:

Spirea japonica (Japanese Spirea): This is a deciduous shrub with clusters of pink flowers that bloom in summer. It’s a good companion because it enjoys the same sun and soil conditions.

Sedum spectabile (Showy Stonecrop): This is a hardy perennial with succulent leaves and star-shaped flowers that bloom late summer through fall. They prefer full sun and well-drained soil, much like the Japanese Barberry.

Salvia nemorosa (Meadow Sage): A perennial with spikes of violet-blue flowers from early to late summer. It’s attractive to pollinators and also enjoys full sun.

Nepeta x faassenii (Catmint): A hardy perennial with grey-green leaves and lavender-blue flowers that bloom from late spring into early fall. It’s drought-tolerant and attracts pollinators.

Perovskia atriplicifolia (Russian Sage): This perennial plant has silvery foliage and blue-purple flowers that bloom in summer, providing a nice color contrast with Barberry’s foliage.

Hemerocallis (Daylilies): These plants provide bright summer color in a variety of shades. They’re also quite hardy and adaptable.

Echinacea purpurea (Purple Coneflower): A favorite of pollinators, these perennials sport purple flowers from mid-summer to fall.

Penstemon digitalis (Foxglove Beardtongue): With tall spires of white flowers in late spring and early summer, these plants attract hummingbirds and butterflies.

Coreopsis verticillata (Threadleaf Coreopsis): These sun-loving perennials bloom from early to late summer with yellow flowers.

Rudbeckia fulgida (Black-eyed Susan): Another favorite of pollinators, these sport yellow flowers from mid-summer to fall.

Achillea millefolium (Yarrow): This perennial has flat-topped clusters of flowers in shades from white to red. They bloom from late spring to fall and attract beneficial insects.

Geranium sanguineum (Bloody Cranesbill): This hardy geranium blooms from late spring to early fall with magenta flowers. Its low, spreading habit helps to cover the ground around taller plants like Barberry.

Stachys byzantina (Lamb’s Ear): This perennial is grown for its fuzzy, silver-gray leaves. It’s a good filler in any sunny border.

Lavandula angustifolia (English Lavender): A perennial favorite for its fragrant flowers and foliage. It blooms in early to mid-summer and thrives in full sun and well-drained soil.

Growing Tips

Japanese Barberry is a tough, adaptable shrub that’s relatively easy to grow. Here are some steps you can follow:

Location and Soil: Select a location with either full sun or partial shade. Japanese Barberry tolerates full shade. While Berberis thunbergii can tolerate a range of soil types, it prefers well-drained soil.

Planting: Dig a hole twice the width and just as deep as the root ball of the plant. Place the plant in the hole, ensuring the top of the root ball is level with the surface of the surrounding soil. Backfill the hole, firming the soil gently around the plant.

Watering: After planting, water the shrub thoroughly. During the growing season, water regularly, especially in dry periods. However, once established, Japanese Barberry is relatively drought-tolerant.

Mulching: Apply a layer of mulch around the base of the shrub to help retain soil moisture and suppress weeds.

Pruning: Prune Berberis thunbergii after flowering. Pruning is usually done to maintain shape and remove any dead or diseased wood. However, keep in mind that this plant has thorns, so use caution.

Fertilizing: While not strictly necessary, you can feed Berberis thunbergii in spring with a slow-release, balanced fertilizer to encourage robust growth.

Pests and Diseases: Generally, this plant is quite hardy and resistant to most pests and diseases. Still, it can occasionally be affected by powdery mildew, rust, and certain insect pests.

Remember, it’s always a good idea to check with your local extension service or garden center for specific recommendations suited to your local conditions and climate. Also, note that Berberis thunbergii can be invasive in certain regions, so please make sure it is appropriate to plant in your area.