How to Grow and Care for Mahonia

Most mahonia shrubs are densely textured with eye-catching, large foliage. Their leaves look very similar to toothed holly leaves. Mahonia are often called holly-leaved barberries since they are in the barberry family but look much like holly shrubs. Mahonia are well-suited to shady spots in your yard and are popular as privacy hedges. Because of their architectural, dramatic appearance, they're often used in minimalist landscape designs, especially in southern states.

North American native woodland plants, mahonias are easy to grow and have an almost tropical look. Most floral sprays are fragrant golden-yellow in late winter or early spring and attractive to pollinators like bees and butterflies. The dark bluish-black berries appeal to various birds that might also take refuge in the thick, green foliage.Part of the appeal of these upright evergreen shrubs is that they offer year-round interest, and the spiky foliage is deer-resistant. Plant mahonias in spring or fall when the temperatures are mild.

Is Mahonia the Same as Oregon Grape?

Oregon grape is one type of mahonia species (Mahonia aquifolium). There are more than 70 species of mahonia, all in the barberry family. The flowers are attractive to pollinators and the berries (not actual grapes) are favorites among some birds and mammals. The sturdy foliage provides cover for many small animals.

Mahonia Care

Mahonias are known to be slow-growing, hardy, and low-maintenance shrubs. They don't like to be moved, and appropriate site selection is essential for their success. Protect your shrub from freezing winds, as these can burn the plant in the winter, and make sure they have enough space to grow, as they aren't fans of being crowded.

Light

Most mahonia can tolerate full sun and heavy shade but thrive in partial shade positions. Deep shade can result in leggy growth for some species.

Soil

One of the advantages of mahonia species is that they don't tend to be particular about the type of soil they grow in. They usually do well in sandy, loamy, and clay types and across various pH levels. The soil just needs to be moist and well-drained.

Water

Generally, mahonias do best with regular deep watering while establishing (especially during the first year), although you should avoid waterlogging. Once established, they're known for being pretty drought-tolerant and will usually only need watering when there are hot, dry spells.

Temperature and Humidity

Apart from the danger of foliage burn because of freezing winds, mahonias usually tolerate a wide range of temperatures. They're typically able to handle temperatures as low as 5 degrees Fahrenheit. However, mulching in the fall around the shrub to protect the roots could help if temperatures drop as low as this.

Fertilizer

These plants don't need a rigorous regime of fertilization. An annual spring feeding with a slow-release, low-nitrogen fertilizer or a rich layer of mulch or compost with fish and bone meal should be sufficient.

Types of Mahonia

Around 70 species are in the Mahonia genus, with more cultivars and hybrids. Some popular, readily available varieties include:

• Oregon grape (Mahonia aquifolium): Sometimes called Berberis aquifolium; grows about 6 feet tall; hardy in USDA zones 5 to 8
• 'Marvel' mahonia: Upright growth habit; large fronds; fragrant sprays of flowers in late fall or early winter; clusters of black berries in summer or fall
• Creeping mahonia (Mahonia repens): Low-growing shrub (reaches around 1 foot tall); works well as a leafy ground cover; hardy in USDA zones 5 to 8
• Frémont's mahonia (Mahonia fremontii):Reaches up to 8 feet tall; hardy in USDA zone 5
• Mahonia x media 'Charity': Tall, tough, and adaptable hybrid; can reach up to 15 feet tall; often used to create a natural privacy fence; hardy in USDA zones 7 to 9
  

Warning

It's worth noting that leatherleaf mahonia (Mahonia bealei) has been a popular ornamental species, but it is now classed as highly invasive in many southern states.

Pruning

Mahonias do not have a demanding pruning regime. However, light pruning every few years in early spring after any frosts have passed can encourage healthy foliage growth. You can also help retain a tidy look by thinning out crowded branches.

If your shrub has been growing in deep shade, resulting in leggy, straggly growth or tall specimens that have become bare at the base, cutting it back to the ground can help it recover a more compact, full habit. After cutting back like this, it's a good idea to mulch around the shrub base and offer a light feed to encourage new, healthy growth.

It's also good to control any plant suckers that sprout from this slow and steady grower. You might want to remove these if you don't want the space overcrowded with mahonias.

Propagating Mahonia

Most mahonia species propagate readily from cuttings taken in the late summer or early fall before flowering. Following the steps below can help to increase the chance of success:

1. Select a cutting of around 6 inches from semi-ripe, current season growth.
2. Remove the leaves from the bottom half of the cutting.
3. Dip the cut end in rooting hormone.
4. Pot up in moist, well-drained potting soil.
5. Keep in a warm spot in a greenhouse or indoors.
6. Cover with plastic to hold in the moisture.
7. Keep moist until roots take hold.

How to Grow Mahonia From Seed

To attempt to grow new mahonia from seeds, try following the steps below for spring planting:

1. Separate the seeds from the fleshy berries
2. Cold stratify any seeds collected for a minimum of one month
3. Move the seeds to a warmer location (around 65 to 70 degrees Fahrenheit) and leave them for another month
4. Sow the seeds around 1/4 inch into the potting soil

Alternatively, you can sow the seeds directly in the ground in the fall and keep your fingers crossed for spring germination.

Potting and Repotting Mahonia

Because of their spreading habit, mahonia generally isn't suited to growing in containers. For best success, grow it in the ground with plenty of space for it to spread.

Common Plant Diseases

Mahonias are robust species; pests and serious diseases aren't common problems. They can sometimes suffer fromrustorpowdery mildew(which causes brown spots on the foliage). While neither is typically fatal, they can cause curling, withering, or dropping leaves.

Watering the shrubs at the plant base rather than over the leaves, avoiding a damp location, and removing infected sections can help minimize these problems. Fungicides can be used if the problem is difficult to control.Mahonia aquifoliumis particularly susceptible to rust.

From: thespruce