Birch trees are known for their striking white bark and vibrant green leaves that turn golden yellow in autumn. However, some varieties of birch trees actually produce leaves in shades of purple and maroon. In this article, we’ll explore the different types of birch trees that have purple foliage and what causes this unusual coloration.
Weeping Birch
One of the most popular purple-leaved birch trees is the weeping birch (Betula pendula ‘Purpurea’). This graceful, weeping tree has branches that cascade toward the ground. The leaves emerge a deep purple-red color in spring and retain a reddish-purple shade throughout the summer before turning yellow in fall.
Weeping birches with purple foliage are prized for their unique beauty in landscapes. The striking color provides great contrast against green lawns or lighter colored plants. They look particularly elegant near water features or ponds. One thing to note is that the leaves may scorch and turn brown during hot, dry weather. Providing adequate moisture will help maintain their vibrant color.
Heritage Birch
Another purple-leaf birch variety is the heritage birch (Betula nigra ‘Cully’). This is a striking, upright tree with reddish-purple leaves that are slightly smaller than other birch species. The bark is cream-colored when young and develops the characteristic white, papery bark as it matures.
Heritage birch is an excellent choice for a medium-sized ornamental tree in the landscape. It can grow 40-50 feet tall with an oval to pyramidal habit. The deep reddish-purple foliage provides great color contrast in the garden. It’s one of the most heat tolerant of the purple-leaf birches.
River Birch
Some selections of river birch (Betula nigra) also exhibit reddish-purple leaves when young. The Dura-Heat® river birch is a cultivar that emerges with bronze-purple spring foliage that matures to greenish-red in summer. It was bred to be very heat and drought tolerant.
Normal river birch trees have green leaves, so be sure to look for a specific variety like Dura-Heat® to get the purple foliage. River birches are fast-growing, adaptable trees ideal for wet sites or drier soils. They work well in large landscapes and can grow 50-70 feet tall.
Japanese Birch
Japanese birch (Betula platyphylla var. japonica) also may have purple-tinged leaves. It’s a medium-sized birch tree native to Asia. The bark is white and exfoliates in papery strips like other birch trees. The foliage emerges with a slight purple cast then matures to green by summer.
This birch species is very ornamental but can be difficult to find. It’s primarily grown for its beautiful peeling white bark that provides great winter interest. Look for specific cultivars labeled as having purple-tinged spring foliage to get this effect.
What Causes the Purple Leaf Coloration?
The striking purple and maroon foliage on these birch trees is caused by the presence of anthocyanin pigments. Anthocyanins are flavonoid compounds produced by plants that act as a sunscreen, protecting leaves from damage by ultraviolet light.
They also act as antioxidants to help leaves cope with stressors like heat and drought. Birch trees with high anthocyanin concentrations produce red, purple, or bronze leaves. The pigments are usually most abundant when leaves first emerge then fade over the season as chlorophyll develops.
Growing Conditions
Most purple-leaved birch trees thrive in a similar environment to other birch species. Here are some key growing requirements:
- Soil – Prefers moist, well-draining, acidic soil high in organic matter.
- Sun – Grows best in full sun to part shade.
- Water – Needs regular irrigation and adequate moisture.
- Hardiness Zone – Hardy in zones 3-9, depending on variety.
- Maintenance – Occasional pruning when young to develop good structure.
Make sure to choose a planting location that provides enough sun to encourage vivid purple leaf color. Some afternoon shade can be helpful in extremely hot climates. Pay special attention to watering needs for purple-leaf birch trees since they are prone to drought stress and scorching.
Companion Plants
The striking purple foliage of these birch trees allows many options to create gorgeous companion plantings. Here are some ideas for complementary perennials and shrubs:
- Purple coneflower (Echinacea purpurea)
- Russian sage (Perovskia atriplicifolia)
- Lilac (Syringa vulgaris)
- Blue iris (Iris versicolor)
- Ornamental grasses like purple fountain grass (Pennisetum setaceum)
- Yellow and gold foliage shrubs like ninebark or privet
Repeat touches of purple plants like lavender, asters, and purple coral bells (Heuchera) will beautifully echo the birch’s foliage. Contrasting bright whites and yellows helps the purple birch leaves stand out even more.
Common Pests and Diseases
In general, birch trees are resistant to most pests. However, there are a few potential problems to be aware of:
- Birch leafminer – Larvae feed between leaf surfaces, creating brown blotches. Usually just cosmetic damage.
- Bronze birch borer – Larvae bore into trunk and branches, potentially killing branches or whole tree.
- Aphids – Suck plant juices from leaves and twigs. Can cause leaf curling and stunting.
- Leaf spot – Fungal disease causing small black leaf spots. More prevalent in humid climates.
Prune out infested branches, avoid unnecessary stress, and use preventative treatments to help manage pests. Proper care and siting will go a long way in keeping purple-leaf birch trees healthy and thriving.
Frequently Asked Questions
How fast do purple-leaf birch trees grow?
Growth rates vary by cultivar, but most purple birches grow at a medium to fast pace. Weeping birches may reach 40 feet tall and 20 feet wide within 20 years. Heritage and river birch often add 2 or more feet of growth per year when young.
Do purple birch trees lose their leaves in winter?
Yes, like other deciduous birch trees, purple-leaf varieties lose their foliage in autumn. This allows them to go dormant through winter then leaf out with new purple growth each spring.
Are purple birch trees safe for yards with kids/pets?
Purple-leaf birch trees are not toxic and are generally safe around children and pets. Supervise young kids around any tree to prevent damage to the tree. Sap flows can also stick to fur and paws if pets climb or scratch the bark.
How can you tell a purple birch tree apart from other birches?
Look at the leaf color. Most other birches will have plain green leaves while purple varieties exhibit reddish-purple hues on the foliage. The bark between most types of birch trees looks quite similar – white, paper-like, and peeling.
Conclusion
With their captivating purple foliage and attractive bark, it’s easy to see why purple-leaf birch trees are gaining popularity in gardens. A few varieties to look for are weeping birch, heritage birch, river birch, and Japanese birch. Provide ample moisture, sunshine, and minimal pest pressure for the healthiest and most vivid purple color expression. Then sit back and enjoy the unique beauty these uncommon trees add to the landscape.