How to Grow and Care for Mahonia

Most of the shrubs in the mahonia genus are densely textured with eye-catching, large foliage. They are shrubs 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. The fragrant golden-yellow late winter or early-spring blooms are attractive to pollinators like bees and butterflies. The dark bluish-black berries appeal to a range of birds, who 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.

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 important for their success. Protect your shrub from freezing winds as these can cause burn 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 they 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 a range of pH levels. The soil just needs to be moist and well-drained.

Water

Generally, mahonias do best with regular deep watering while they're 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. If temperatures drop as low as this, however, mulching in the fall around the shrub to protect the roots could help.

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

There are around 70 species of plants in the Mahonia genus and many more cultivars and hybrids. Some popular, readily available varieties include:

• Oregon Grape (Mahonia aquifolium): Also known by the botanical synonym Berberis aquifolium, this species typically grows to around 6 feet tall. Hardy in USDA zones 5 to 8.
• Creeping mahonia (Mahonia repens): Unlike many mahonia species, this is a low-growing shrub (reaches around 1 foot tall) that 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. This shrub is hardy in USDA zone 5.
• Mahonia x media 'Charity': This tall, tough and adaptable hybrid can reach heights of up to 15 feet tall and is often used to create a natural privacy fence. Hardy in USDA zones 7 to 9.
  

Pruning

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

If your shrub has been growing in deep shade, resulting in leggy, straggly growth, or tall specimens 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 to become overcrowded with mahonias.

Propagating Mahonia

Most mahonia species propagate readily from cuttings taken in the late summer or early fall before flowering commences. 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 a 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 aren't suited to growing in containers. For best success, stick to growing in the ground where there is plenty of space to allow for this spread.

Common Plant Diseases

Mahonias are robust species, and pests and serious diseases aren't common problems. They can sometimes suffer from rust or powdery mildew (which causes brown spots on the foliage). While neither are 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 you to minimize these problems. Fungicides can be used if the problem is difficult to control. Mahonia aquifolium is particularly susceptible to rust.