Buxus Care Guide - Caring for Box Topiary

How to Care for Box Topiary

We would like your box plant (Buxus sempervirens) to be happy and healthy and last for years to come.

On this page you will find our care advice specifically for box plants that will let you know what your plant needs.

We have also included our recommended products, products that we use ourselves, that will help you keep your plant looking at its very best.

We highly recommend you repot your plant from its original planter and give it a feed.

Box is a hungry plant with a weak root system so frequent feeding with a foliar feed is a good idea.

Two things in particular you should watch out for are box blight disease and box tree caterpillars. The earlier you can take action the better your plants recovery will be. 

 

Buxus Care Instructions

Botanical Name	Buxus sempervirens
Common Name	Box
Description	Box is a very dense small-leaved native evergreen with dark green glossy foliage. It's slow growing and shade tolerant. Traditionally it has been used for formal hedging and topiary work.
Flowering	In spring, plants display a show of male flowers with conspicuous yellow anthers that surround single female flowers.
Toxicity	All parts may cause severe discomfort in ingested.
Hardiness	Hardy in all of UK and northern Europe (-20C to -15C)
Height / Spread	Ultimate height: 8m. Ultimate spread: 8m. Time to ultimate height: 20-50 year(s). Box will grow 10-15cm (4"-6") a year when fed and watered.
Aspect	Happy in any aspect from full sun to full shade although some shelter is recommended as a strong prevailing wind may cause leaf scorch. Excessive sunlight can result in sun-scorched leaves but plants will recover from this. Some bronzing of the foliage may occur in the Autumn.
Soil	Acid, alkaline or neutral. Moist but well-drained. Chalk, loam or sand. Use a good compost like No 2 Supreme Potting Compost when potting on.
Watering	Water well during the spring and summer but sparingly in the winter.
Feeding	Add slow release fertilizer such as Osmacote during the Spring and provide liquid feed every few weeks during the summer months. Stop feeding after August, until the following Spring. Recommended Products: Westland Buxus 2 in 1, Top Buxus
Pruning	Box responds well to clipping and new growth can be trimmed throughout the growing season (June to the end of August) to retain the shape of the plant. Clip as lightly as possible during the first year to allow the roots to establish themselves. When pruning a box topiary frame, let the foliage grow inside the frame. Clip the foliage that exceeds the frame. Roots can be trimmed if required.
Pests	May be attacked by aphids, leaf-mining moths, thrips and red spider mite (in hot weather). Look out for Box Caterpillar – these are green with black stripes and spots. They will easily eat an entire plant’s leaves…so move them elsewhere if you spot one! Recommended Products: SB Plant Invigorator
Diseases	May be subject to a leaf spot and box blight. Box blight is a fungal disease that requires immediate attention. See our full guide below. Recommended Products: Top Buxus, Fungus Clear Ultra

How to Handle Box Blight

Box blight is a fungal disease that disrupts the transport of water within the plant.

The spores that cause it can be spread via the wind, birds and animals, planting material, garden tools, footwear or clothing.

It results in die back of not only leaves but stems disfiguring the plants.

To try and rectify this and restore the plants ruthless measures are necessary.

Firstly, remove all affected stems. Box can be cut back severely and now is the time. You can use secateurs, hedge sheers or electric hedge trimmers. Whatever you use be sure to disinfect before and after use. If the plants are formal keep their shape but cut back as much or even a bit more than necessary to remove all infected parts. You will see green in the centre of the stems you have cut back when you are in healthy wood.

Once this is done remove all the cuttings and then carefully remove as much debris as possible from under and around the plants. This not only removes as much infected material as possible but also allows more air to the centre of the plants.

We now need to strengthen and rejuvenate the plants.

Apply a granular slow-release fertilizer that preferably lasts a full 12 months. Ensure it is well watered in. A regular watering is needed. Try and keep the leaves dry and water from the base.

Now apply a product called Top Buxus which is high in nitrogen for strong green growth and sulphur which is a natural fungicidal agent which will help defend against any blight.

Use 1 tablet in a litre of water and apply to every surface of the plant and around the base.

After this is done apply a well composted bark mulch. This will help prevent any remaining infection in the soil bouncing back onto the plants when it rains.

As the plants start to grow back apply a foliar seaweed spray which is a foliar based fertilizer to further strengthen the plants.

Be patient, it could take up to 3 months for your box plants to recover but you have done everything possible for their rejuvenation.

 

   

Other Diseases

Volutella Blight

What is it?

Similar to box blight, Volutella blight has comparable symptoms but without the black streaks. It is caused by the fungus Pseudonectria buxi (P.buxi) and also known as leaf and stem blight.

Symptoms

Initial symptoms are the delayed emergence of new growth. Patches of wilted and discoloured leaves increase in size before falling from the plant. Spores masses that often appear underneath the leaves in wet or humid conditions are pink rather than white for box blight.

Treatment

Early diagnosis and plant care are key to controlling Volutella blight. Unlike box blight full plant recovery can be expected if cultural conditions are improved. This includes the removal of diseased branches when foliage is dry and old leaves from the interior of infected plants. Destroy the debris and wipe clean cutting tools with a suitable disinfectant to prevent the spread of further disease. An application of Top Buxus, high in nitrogen for strong growth and sulphur a natural fungicidal agent to defend against blight will benefit the plant.

Control & Prevention

Keep your plants in good condition with regular clipping, this will improve air circulation and increase sunlight throughout the plant. Ensure this is done in dry weather as P. buxi requires wounds for infection and associated with clipping in wet weather. If you have to water your plants try to to do this in the morning so foliage can dry during the day before temperatures drop. An application of granular slow releasing fertiliser will keep plants strong and healthy.

Box Rust

What is it?

Box rust is caused by a fungus Puccinia buxi. It is not serious and rarely causes problems.

Symptoms

Box rust is identified by inspecting the leaves for rust coloured blister like spots on both sides of the leaves. The spores develop in the autumn and winter where they infect new leaves in the spring and summer.

Treatment

Clip off the infected leaves or spray with a fungicide specifically for rust diseases.

Macrophoma Leaf Spot

What is it?

Macrophoma leaf spot is caused by the fungus Macrophoma candollei, a weakly pathogenic fungus. Similar to Volutella blight it can be managed by improving cultural conditions.

Symptoms

Macrophoma leaf spot can be identified by many black raised fruiting bodies found on dying or dead straw coloured leaves.

Control & Prevention

Following our advice on the treatment, control and prevention of Volutella blight, proper pruning and thinning is the most effective way to manage this disease. Thinning the plant helps to increase air circulation helping the leaves to dry out so they are not constantly moist.

Phytophtora Root Rot

What is it?

Phytophthora species are microscopic fungus like organisms found in the soil that cause root and stem base decay of plants. It is usually found in soils that are heavy and waterlogged and can infect trees, woody plants and vegetables.

Symptoms

Symptoms seen above ground generally do not develop until root decay is well advanced. There are few early warning signs and most plants will appear drought stressed despite regular watering. Wilting, yellowing or scant foliage and branch dieback are common and will continue until the plant dies. Below ground, roots, collar and stem bases of infected plants will reveal a poor root system.

Treatment

Treatment of infected plants is very difficult as there are no early warning signs by which point the damage is done. In some cases however, plants can be saved by removing all soil from the base all the way down to the top of the main roots and cutting back any bark that is soggy or dark. This exposes the root system allowing it to dry and slowing the spread of the disease.

Control

Improving soil drainage helps to reduce the risk of plants to the disease. Where it is present, infected plants should be destroyed and the soil from the root and surrounding areas removed and replaced with fresh topsoil. Replanting in the area of less susceptible species is advised.

Pests That Like Box

Box Sucker

What is it?

Box sucker are sap sucking insects also known as psyllid that feed on the young shoot tips of box plants in the spring. They secrete chemicals into the plant which prevent the the shoots from developing properly. They are pale green, less than 2mm long with flattened bodies. They produce a white waxy secretion which collects on or around the plants.

Symptoms

In the spring, the growth of new shoots is stunted and their tips become curled with a cabbage like appearance.

Control

Nip out the damaged shoots of younger plants as you see them. Older plants can be clipped as normal with a second clipping later in the summer to remove most of the eggs. These should be removed and destroyed, not composted.

Box Tree Caterpillar

What are they?

Box Tree Caterpillars are the larvae of a moth that feeds on box plants. It is a devastating pest that can completely strip plants of their leaves. Young caterpillars are greenish-yellow with black heads and 1.5-2cm long while older caterpillars can be up to 4cm long with black and white stripes along the length of the body.

Symptoms

The first signs of an attack are a web like substance on the leaves where they produce a webbing over their feeding area. On trimmed plants there may also be patches of dieback - not to be confused with dieback caused by box blight. Eggs are pale yellow which later develop a black spot and found on the underside of box leaves.

Control

As this is a relatively new pest, control is limited. Ideally and where possible, caterpillars should be removed by hand. Alternatively they can be sprayed with a suitable insecticide.

Box Leaf-Mining Gall Midge

What are they?

The Box Leaf Mining Gall Midge otherwise known as Monarthropalpus flavus is a tiny fly that lays its eggs amongst new foliage from April to May.

Symptoms

The larvae feed inside the foliage which causes a swelling on the leaf surface and discolouration and small patches of dieback.

Control

Damage caused is mostly aesthetic and won't affect the plant vitality and can be tolerated. Control is difficult as pests reside inside the protection of the leaf, however they can be treated using systemic insecticides.

Recommended Products: SB Plant Invigorator

Mussel Scale on Box

What are they?

Mussel Scale are tiny sap sucking insects around 3mm long with soft bodies hidden under shells or scales hence the name.

Symptoms

They live mainly on the woody stems of host plants but on occasion will appear on small leaves. Light infestations are generally harmless but in cases where box plants are heavily affected it will cause them to lack vigour and stems to dieback.

Control

Plants should be checked regularly from spring onwards so any action can be taken before large harmful infestations take hold. Where there are small occurrences of the insects, growth of the plants may not be affected so won't require any control. If sprays are to be used the best time is early May and June, plant based sprays give good control while unlikely to affect their larger ladybird predators which should be encouraged.

Recommended Products: SB Plant Invigorator

Box Red Spider Mite

What are they?

Red Box Spider Mite are tiny creatures specific to box. They feed on the undersides of leaves by sucking sap during spring and early summer.

Symptoms

The feeding on the underside of leaves causes fine white mottling. The mites die out by late summer and overwinter as eggs which are laid on stems and again on the underside of leaves.

Control

While the mites are difficult to control, they do not do any lasting damage to the plant. They can be sprayed with plant oil sprays every five days which will eventually eliminate the life cycles of the mites.

Recommended Products: SB Plant Invigorator

 

 

Further Reading

The RHS website has further information of pests and diseases that can affect box plants: https://www.rhs.org.uk/advice/profile?pid=851