With the Mahonia, Mother Nature created a jewel among ornamental trees. Attributes such as evergreen foliage, golden yellow flowers and edible berries make gardeners' hearts beat faster. If you still have unanswered questions, you can find competent answers here.
What should you know about caring for Oregon grapes?
Mahonies are attractive, evergreen ornamental trees with golden yellow flowers and edible berries. They prefer humus-rich, sandy-loamy soil in partially shaded locations and require little care. For an opaque hedge, plant appropriately spaced and cut back after flowering.
Planting Mahonia correctly
Before you start the actual planting, place the potted root ball in a bucket of lukewarm water. Then loosen the soil thoroughly and create a spacious planting pit. If the soil quality is not optimal, add soil additives such as compost, horn shavings or sand. The steps continue:
- Unpot the plant and place it in the middle of the pit
- Plant so deep that the top of the root ball is a few centimeters below the ground
- Press the substrate and water immediately
In the bucket, spread drainage over the water drain in the bottom as an effective prevention against waterlogging. Suitable materials are pottery shards, chippings or expanded clay.
Care tips
Hardly any ornamental shrub is easier to care for. Water the mahonia in the bed regularly when it is dry and in the container. When budding begins, the plant enjoys initial fertilization in the form of compost or liquid fertilizer. After the hibernation period, thin out the trees thoroughly. Ideally, the plant should receive a shape and maintenance cut immediately after flowering. In order for the mahonia to develop an opaque privacy screen as a hedge, it tolerates repeated pruning throughout the year in order to encourage the shoots to branch out vigorously. As long as it's not freezing or the blazing sun is shining, you can use the secateurs without hesitation.
Which location is suitable?
The mahonia is considered to be extremely location-tolerant. The magnificent shrub achieves its optimum in partial shade. The plant thrives best in a sunny location as long as the soil is moist enough. In addition, the ornamental tree does not deny the enchanting flowers even in a shady location. The flexibility continues in relation to the soil conditions, because whether as a hedge or solitary, the Mahonia happily spreads its roots in any normal garden soil.
The correct planting distance
The tall species and varieties are impressively displayed in solitary positions. In this case, plant one bush per square meter. If the plant functions as an opaque hedge, the growth width defines the planting distance. For the majestic Mahonia 'Winter Sun' with a width of 80 to 150 cm, a distance of 100 cm from the neighbor is just right. Ideally, you should plant 3 copies of the dwarf variety 'Apollo' per meter.
What soil does the plant need?
The mahonia feels at home in standard garden soil. Ideally, the soil is humus, sandy-loamy and nutrient-rich. The top priority is first-class permeability, because the shrub does not want to be confronted with waterlogging. Cultivated in a planter, a commercially available compost-based potted plant soil (€18.00 on Amazon) enriched with a few handfuls of lava granules or expanded clay is an option.
What is the best time to plant?
Regardless of whether the Mahonia functions as a solitary shrub or an opulent hedge, the planting period extends over the entire growing season. The ornamental tree receives ideal starting conditions for a long plant life if it is planted in the warm, sunny soil in autumn.
When is flowering time?
At no time of the year do you have to go without the enchanting panicle blossoms of a Oregon grape. The shrub is available in a variety of species and varieties that have different flowering times. For example, if you combine the following varieties in a hedge, there will always be a flower to admire:
- Winter Sun (Mahonia media): flowering period from January to April
- Ornamental mahonia (Mahonia bealei): flowering period from the end of February to April
- Common mahonia (Mahonia aquifolium): flowering period from April to May
- Chinese mahonia (Mahonia bealei) blooms from June to August
- Charity (Mahonia x media) blooms from September to November
- Hivernant (Mahonia japonica): flowering period from November to February
Cut mahonia correctly
The mahonia is one of the ornamental trees that tolerates pruning. This property means that corrective interventions on the hedge or bush with scissors are possible at any time during the year. It is best to carry out central pruning after flowering, as at other times there is a risk of accidentally removing the buds that have already formed. In early spring, the shrub should also be thinned out thoroughly by cutting off all dead wood at the base.
Watering Mahonia
The frugal shrub is content with natural rainfall under normal weather conditions. Only in dry summers should you water the plant directly onto the tree disc. The substrate dries out more quickly in the pot, so the moisture content must be checked every few days in order to water if necessary.
Fertilize Mahonia properly
In sufficiently nutrient-rich soil, the deep-rooted shrub takes care of itself. However, in rather poor soil and in pots, we recommend starting fertilization in spring with compost or liquid fertilizer, which should be refreshed every 2-3 weeks during the flowering period. Winter-flowering varieties gratefully accept a mulch layer of nutritious leaf mold or compost, as this way the soil is better protected from frosty temperatures.
Diseases
If the plant is weakened due to negligence in care, the following diseases strike mercilessly:
- Mildew: Treat with a mix of fresh milk and water in a ratio of 1:9
- Rust disease: If there are red and yellow pustules on the leaves, make a radical cut back
Wintering
In the Central European climate, only the common mahonia has unconditional winter hardiness. Highly bred varieties have lost some of their frost resistance in favor of their beauty. All of the evergreen ornamental trees are sensitive to the intense winter sun. Therefore, give the shrub the following winter protection:
- Before the first frost, spread a layer of mulch made of leaves, conifers or compost
- Protect the shoots from sunlight in winter with reed mats or jute ribbons
- Cover the bucket with several layers of bubble wrap and place it on a wooden block
- During the winter, move the shrub in the planter to a shady location
Since the plant wears its green foliage all year round, evaporation continues at a reduced level in winter. Therefore, water the shrub and hedge every now and then on a frost-free day.
Propagate Mahonia
A garden gem like the mahonia understandably awakens the desire for more specimens. Choose one of the following methods of propagation:
- Cut cuttings in summer to stick them in the ground in a partially shaded location
- Dividing the root ball in autumn or spring
- Separate vital runners and place them in the ground in the new place
You can also harvest the berries and remove the seeds from them. After stratification, sow the light germinators preferably behind glass and care for the seedlings until they are planted out from a height of 20 cm.
How do I transplant correctly?
The mahonia copes well with a change of location if it is carried out while the sap is dormant. Cut the shrub back by about a third to compensate for the lost root volume. Then cut off the roots widely and lift the plant out of the ground in order to plant it in the new place without any further delay. A plentiful water supply in the next few weeks will determine the success of the campaign.
Mahonia in a pot
Without a doubt, caring for a mahonia in a pot is a little more extensive than in a garden bed. However, the effort remains manageable, as the following list of all important measures shows:
- Check regularly with a thumb test whether there is a need for watering
- Water the plant directly to the root area and do not sprinkle it
- From the beginning of budding until the end of the flowering period, fertilize liquidly every 2-3 weeks
- Before winter, cover the soil with leaves and protect the shoots from the sun with jute ribbons
- Wate the evergreen plant every now and then on frost-free days
So that the shrub in the pot doesn't grow over your head, cut it back by a third immediately after flowering. In addition, the plant should be thinned out after winter.
Is Oregon grape poisonous?
The use of mahonia berries as jam or fruit wine should not hide the slight toxic content of the plant. All parts contain toxic berbine. The shrub is primarily of concern for small children up to the age of 3 and for pets. If the berries are eaten raw, they cause unpleasant symptoms of poisoning, such as vomiting, stomach pain and diarrhea.
Brown leaves
Brown leaves in spring signal frost damage or burns from the intense winter sun. Thanks to a Mahonia's robust pruning tolerance, remove the discolored, frozen foliage to make room for new growth. For the next winter season, we recommend protecting the shrub and hedge with raffia or reed mats.
What are the differences between mahonia and barberry?
There is no doubt that the mahonia and the barberry are botanically closely related to each other. However, the classification into a common or separate plant genus is still controversially discussed among botanists. However, the following differences are obvious that distinguish a mahonia from a mountain berry:
- Panicle-like inflorescences
- Evergreen, imparipinnate foliage
- No thorns
- Edible berries
When you reach into a barberry, you will become painfully aware of a significant difference to the mahonia, because this shrub is covered in sharp thorns.
Beautiful varieties
- Winter Sun: Magnificent winter bloomer as a solitaire and hedge from January to April with light yellow flowers; Growth height 150-200 cm
- Apollo: Compact plant with thorny, toothed foliage that turns reddish in winter; Growth height 50-80 cm
- Decorative mahonia: A top-class shrub thanks to its light yellow flowers and blue-black frosted fruits; Growth height 200 cm
- Orange Flame: The plant impresses with bright orange autumn leaves; the ideal shrub for the container; Growth height 50 cm
- Creeping mahonia: Ground-cover plant for shady locations that eagerly forms runners; Growth height 30 cm
- Hivernant: Beautiful Japanese Mahonia that blooms yellow from November to February; Growth height 100-150 cm
- Charity: Autumn-flowering shrub for almost all locations from sunny to shady; Growth height 200 cm
