Mahonia is a genus with 70 species of perennial shrubs belonging to the Berberidaceae family, its origin is located in East Asia, the Himalayas, North America and Central America. It has pinnate leaves between 10 and 50 cm and flowers that are generated in clusters of 120-50 cm long. The main attraction, and for which it is planted in gardens around the world, are casually its always green foliage and for its yellow flowers that occur in winter and spring. On the other hand, after flowering, it produces edible berries rich in vitamin C. For all this it is that an article on how and when to prune Mahonias could not be missing on this website.

Note: Please note that the advice given here is general, this blog is consulted from many countries in the world, with totally different characteristics, what not all tips will be adapted in the same way in all cases. Once you finish reading the article it will be necessary to analyze all the information and apply what you have learned in the best way. If you have any questions, remember that you can contact us to make your inquiries.

1. How to care Mahonia bush

Before getting fully involved with the main theme of this article, Mahonia pruning, and since it is nothing more than a maintenance technique for this bush, we will see in this section the key points for caring for it.

  • Irrigation: Established mahonias require irrigation infrequently but well in very dry periods only. Do not let the soil around you fill with water.
  • Lighting: Most prefer total or partial shade, although some types tolerate some sunlight.
  • Soil: They thrive in a variety of soil types including loam, clay, calcareous soils and even sand. They show little preference in the pH range of the typical garden soil, growing well in acidic, alkaline or neutral conditions.
Mahonia bush
Mahonia bush
  • Fertilization: Provides an annual mulch with garden compost or rotten manure in September to protect against frost and control weeds. In addition, feed the bush with some blood, fish and bone or with a slow and balanced nitrogen, phosphate and potash release fertilizer around its base in March or April.
  • Propagation: Although the most traditional method is the use of cuttings, with which you make sure you have an identical plant to the previous one, it is also possible to obtain it from its seeds.
  • Diseases and pests: In general terms it can be said that there is no special plague that attacks the Mahonias, since although they can be attacked by aphids and whiteflies they are almost never a problem. As for diseases, there are several varieties that are attacked by fungi, so a control with fungicides can come in handy.
  • Pruning: While it is not a vital maintenance practice for the plant it always comes it can help its development and the aesthetics of this shrub.

2. Tools needed to prune a mahonia

Depending on the variety of mahonia you have in your garden, the size can vary, from 1.5 m high to 4.5 m high. These diversities in size can fit between the need for one tool or another, as well as the type of pruning you want to perform. You can usually manage with one of the following tools:

  • Hand Pruning Shears: Stems up to half inch in diameter can be pruned with hand shears.
  • Lopping Shears: It is suitable to use on stems between half inch and 2 inches in diameter.
  • Hedge Shears: Manual and power shears are available for trimming hedges. Manual shears have long, flat blades with relatively short handles and are good for small jobs. Electric shears are a good choice for larger hedges.
  • Saws: A number of pruning saws are available. These saws come with either curved or straight blades and of variable lengths and points. Curved blades that cut on the draw stroke are easy to use.
  • Protective elements: Never forget to use protective items such as gloves and gardening glasses. You are using sharp tools so protection is important.

Always remember to disinfect tool blades before starting pruning, as well as when switching from one plant to another. This will help you not to disperse diseases and / or pests from one plant to another.

2.1 Needed care of pruning tools

Try to perform the following care in your pruning tools to extend useful life.

  • Use the right tool for a job and avoid twisting or straining it.
  • Clean and oil tools regularly by wiping an oily cloth on blades and other surfaces.
  • Keep cutting edges sharp by regularly using an oilstone.
  • Wooden handles should be varnished or regularly treated with linseed oil to keep them from cracking or splintering.

Keep in mind that if you extend the life of your tools you will not be doing anything other than saving money. 😉

3. Pruning of Mahonias according to the species

As soon as we started the post we defined the Mahonias as a genus of perennial shrubs with about 70 recognized species. This amount of species within the genus makes it impossible to speak, in a general way, about the pruning of Mahonias. That is why to talk about how to prune them we will divide them between those with high growth rates that reach heights above 2.00 m, and smaller ones that do not exceed the height of 1.50 m.

If we should mention a low-growth Mahonia, the most representative is the popular Mahonia aquifolium or better known as Oregon Grape. While among the Mahonias of high growth rate we can cite; Mahonia Japonica, Mahonia Charity and Mahonia Winter Sun.

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3.1 Pruning Mahonia Japonica, Charity and Winter Sun

The Mahonias Japonica, Charity and Winter Sun are shrubs with high growth rates, being able to reach 2.00 m high and 3.00 m wide without problems. If your garden is large, with enough space to let these trees grow freely you probably don’t need to prune them. Like this and everything, and even if you have enough space comes the time that the branches begin to be so thin and long that they look anti-aesthetic. That is why in one way or another you will almost certainly need to prune your Mahonia Charity, Japonica or Winter Sun, let’s see how to do it.

The most advisable is to perform annual pruning in these shrubs, do not let its size has become uncontrollable. Rather cut year after year in an orderly manner so as not to need hard pruning.

Wait as soon as it has finished blooming (usually this will be in early spring), to cut one in three stems. The height at which you can make the cut can be half of the branch or less than 60 cm from the ground. Alternatively, and depending on the need, you can cut branches at ground level. Do not be afraid to cut, shrubs like these respond well to pruning.

In general, and especially if you do not do the pruning of your Mahonia Winter Sun regularly, the first thing you should do are cuts to gain visibility inside the plant. To do this, start by cutting some upper clusters of leaves, this will clear the interior thus facilitating the task.

3.2 How to prune Mahonia aquifolium or Oregon Grape

The Mahonia aquifolium or popularly known as Oregon Grape are perennial shrubs with low growth rates, in general they are 1.00 m high and can rise (if you do not control it) 1.50 m. They are special for small gardens, where the place does not spare.

Since they are plants of small embergadura it will hardly need pruning, unless it has been poorly located and its size as well and everything bothers. Therefore, pruning will be limited to eliminating dried flower clusters and classic cleaning pruning.

If you need to shrink its size you can trim your Oregon Grape by trimming the branches without worrying, preferably do it in stages, citing some branches and giving recovery time. You will see that it will not take long to develop strong new shoots. In addition, pruning will not hurt to facilitate the circulation of air and light inside the plant.

We can conclude that Mahonia aquifolium needs less space than, for example, Mahonia Charity, making it less dependent on pruning than the latter. So and all, if needed, you can cut it on a scheduled basis.

4. General pruning of Mahonia

We have already summarized some of the Mahonias’ pruning needs according to the species, let’s talk now about some general pruning that almost every bush needs. These pruning are:

  • Pruning to shape.
  • Cleaning pruning.

Although the names are super transparent and you should know how to carry out these pruning I will not miss the opportunity to write a little more. 😉

Mahonia bush – Image source

4.1 Pruning to shape

Mahonias are shrubs, that is more than clear, it is also clear that shrubs are generally plants that adapt perfectly to pruning to shape.

The first thing to look for before starting to trim is to densify the foliage. To achieve this, detach all branches, this will promote the generation of new shoots. When these new shoots have developed sufficiently, you should cut them again, do it several times until you reach the desired foliage density.

At the same time that it densifies the foliage, you can go giving the form that you are looking for. Generally in the gardens it is very common to see ball-shaped Mahonias, but you can try others.

If you already gave it the form, the next maintenance pruning will be a piece of cake. It will be enough to look for a cut of a previous pruning, and cut to the height of the same, do the same in each branch and it will not cost you to return to the previous form.

4.2 Cleaning pruning

This Mahonias pruning is the classic pruning that almost all plants need. The objective of the plant is to keep the plant healthy, eliminate useless elements for development and improve flowering to some extent. In the case of this shrub has the advantage of not suffering from major attacks of diseases or pests, this will make the pruning of clean in general be quite light.

As I always say, before starting to trim, take some time to analyze the plant carefully, then you should eliminate the following:

• Start cutting completely dry branches, it will help the aesthetics of the plant.

• If you find branches attacked by a pest or disease (something not very common in the Mahonias), it is time to cut it.

• Trim any branch with bad orientation, crisscrossed that not for some reason clashes with the shape of the bush.

4. When to prune Mahonia

In general and regardless of what species we are talking about, the right time to prune a Mahonia is immediately after flowering. This gives time for the new shoots to grow back and mature during the summer, producing flower buds for the next flowering season.

In the case of cleaning pruning, where dry branches are trimmed, it can be carried out at any time of the year. Since they are dead elements, they will not change the situation of the bush at all. It passes the same with diseased branches, with the difference that must be cut as soon as possible to avoid a spread of the disease or plague.

5. How to prune Mahonias video

We always like to finish the articles with a video, since here we develop crops for different species I will leave you three different videos on three different species. I hope they are useful.

5.1 Pruning mahonia aquifolium (Oregon grape)

Video source plantamnesty channel

5.2 Pruning Mahonia Charity

Video source Brett’s Horticulture channel

5.3 Pruning Mahonia Winter Sun

Video source gardenvilletv channel

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So far we have come up with this brief article about how and when to prune your Mahonia, I hope that everything seen up to here has been very clear, otherwise or do not hesitate to contact us. 😉