When it comes to tall, eye-catching flowers, Bear's Breeches are a great choice. Bear’s breeches are large perennial plants with glossy green leaves and tall spikes of flowers. The foliage is a wide rosette of arching, shiny, dark green leaves that are deeply lobed. They are always touted as architectural plants, and their leaves are often used as a motif in moldings, reliefs, and even jewelry. Many gardeners grow them for their foliage alone, although the flowers are quite nice themselves.
Acanthus means bract, which are modified leaves that are often more colorful than the actual flowers. They help to attract pollinators. The botanical name for bear's breeches, Acanthus mollis, comes from the thorny look of their purple bracts. You can expect to see flowers on this plant from late spring to early summer. Although there are about 30 species of acanthus, only a couple are commonly grown as garden plants. While they are imposing and beautiful, they can be erratic, blooming well in one year and disappointing in another. Bear's breeches plant grows and spreads quickly and is considered an invasive species in parts of the US.
|Common Names||Bear's Breeches, Oyster Plant|
|Botanical Name||Acanthus mollis|
|Plant Type||Perennial, herbaceous|
|Mature Size||3-6 ft. tall, 3-6 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Moist but well-drained|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Spring, summer|
|Flower Color||White, purple|
|Hardiness Zones||6-10 (USDA)|
|Native Areas||Europe, Mediterranean|
Bear's Breeches Care
Bear's breeches are wide plants and need at least 3 to 4 feet of garden real estate each as they like to spread out. Because of its bold leaves, Bear’s breeches pairs well with airy plants, like Crocosmia, Gaura, and ornamental grasses and also can be used effectively on their own. Bloom begins in late spring to midsummer and continues for 3 to 4 weeks. Bloom time depends on your zone and the whims of the weather.
Bear’s breeches can be aggressive growers, spreading and squeezing out neighboring plants. To keep them under control, many gardeners place a sunken border around the plants or grow them in bottomless containers sunk into the ground.
Bear's Breeches is listed as an invasive species in Oregon and a few areas in California in the Invasive Plant Atlas of the United States.
Plants will do best in full sun to partial shade. They need more protection in hot climates, but wherever you grow them, they need at least a few hours of sun to bloom well.
Bear’s breeches like a rich soil with plenty of compost or other organic matter. Once established, they are more accommodating about poor soil, but they absolutely need good drainage, especially in winter. Sitting in cold, wet soil can cause the roots to rot and may kill the plants.
Once established, bear’s breeches are very drought resistant, but perform best with regular watering. An inch a week should be plenty.
Temperature and Humidity
These plants are dependably hardy. Protect your plants during their first couple of winters with a thick layer of mulch. In Zones 6 and lower, continue this practice for the life of your plants.
Bear’s breeches are not heavy feeders. Start with a rich soil and side dress annually with compost. You can use a balanced fertilizer in spring or mid-summer if the plants look like they need it.
Types of Bear's Breeches
- Acanthus balcanicus var. hungaricus, Hungarian Bear's Breeches: The most widely adaptable species, it blooms later and is less susceptible to late frosts.
- Acanthus mollis, Common Bear’s Breeches: This is the most popular species, but it can also be the most temperamental about blooming, with buds being damaged by late spring frosts.
- Acanthus spinosus, Spiny Bear’s Breeches: This is more adaptable than A. mollis and more thistle-like.
In hot climates, the plants can be cut back after flowering. This will encourage fresh new foliage. Gardeners with cold winters should leave the plants standing and allow the leaves to protect the crown. Wait until you see new growth in the spring to cut back any damaged or declining leaves.
Propagating Bear's Breeches
Bear's breeches propagate very easily by themselves, but you can plan to get some of your own to transplant in early spring. They can be propagated by dividing the plants or taking root cuttings. Dividing the mature plants will keep them healthy and blooming at their best. Here's how:
- Bear’s breeches have long tap roots and do not like to be moved. If you want to divide your plants, the best way to do it is to thrust a shovel into the base of the plant’s roots during the fall and leave the plant in place. (Wounding the taproot encourages the plant to sent up plantlets.) The following spring, you should see several new baby plants that can easily be transplanted.
- Simply dig up the new plants, being careful not to damage the roots of either the mother plant or plantlets. Separate any tangled roots with a sharp sterile knife.
- Replant them in a suitable growing site and water the soil until moist.
How to Grow Bear's Breeches From Seed
While this plant does grow from seed, it will take the plant a bit to get established. The best time to start bear’s breeches from seed is the springtime. You can start the seeds indoors at any time or direct sow them in the spring by simply planting the seeds in the desired location and watering. It will take about 21 to 25 days before you see them germinate. Expect to wait several years for them to bloom. They need time to grow and establish their root system before they start to send out flower buds.
Potting and Repotting Bear's Breeches
These plants grow well in large pots or container gardens. Take some of the new plants from a division of the plants outside in the garden and plant them carefully in the pots filled with a mixture of potting soil and peat moss. Not only does this keep bear's breeches in a controlled area (the pot) but it makes for attractive foliage for the outside patio.
Common Pests and Diseases
Insects don’t generally bother bear’s breeches, but those gorgeous leaves can be susceptible to a handful of diseases, with powdery mildew being the usual culprit. Other fungal leaf spot diseases and bacterial leaf spot are other diseases that can crop up. Good air circulation and a dose of homemade fungicide will help take care of these issues. Slugs and snails do like to hide out and feed if the soil is damp, and these pests can do substantial damage if left unchecked. Spraying them with a salt spray solution or using diatomaceous earth will get these pests under control.
Are butterflies attracted to bear's breeches?
Butterflies and other pollinators, including bees and hummingbirds, are attracted to bear's breeches, and you will see them often when this plant is in bloom.
Will bear's breeches grow in shade?
While this plant can grow in shade, you won't see those beautiful blooms like you do when it's planted in its preferred location of full sun to partial shade.
Are bear's breeches plants deer and rabbit resistant?
Both deer and rabbit tend to leave bear's breeches alone.
Bear's Breech. Invasive Plant Atlas of the United States.