Shrubs - your questions answered

Planting shrubs provides low-maintenance structure, colour and climbing interest in gardens large and small. But as with any type of plant, the right care and attention is essential to produce the best results.

We've answered some of your questions about shrubs below to help you give your shrubs the best possible chance in your garden.

• Are Oleander plants poisonous?

Oleander plants are highly toxic if ingested and contact with foliage may irritate the skin. Fumes from burning this plant may also be toxic if inhaled. They're commonly found in public and private gardens.

As with all poisonous plants, if your Oleanders are accessible to animals or unsupervised children, then you should consider carefully removing them.

Wear gloves and long sleeves when pruning or handling them.

• Do plants flower better in containers or planted in the garden?

Many plants flower in response to being slightly stressed - flowering and producing seeds is a method of species survival.

Plants planted in the garden are likely to put their energy into making roots and vegetative growth instead of flowers. Being planted in soil gives plants access to more nutrients and soil moisture than being planted in a pot.

Planting in the ground will not stop your plants blooming, but it will likely delay the process, though is also likely to make the plant much healthier in the long-term.

Use high potash feed to encourage flower bud formation. Avoid using nitrogen rich fertiliser, such as tomato food, as this will encourage lots of foliage growth but no flowers.

• Can bamboo be grown in a garden?

Bamboo can be grown in any garden - in the ground or in containers.

Many bamboo plants have spreading rhizomes and are best grown in containers if you don't want to keep digging bits out. Some bamboos naturally form clumps and are more suitable for borders, such as Black bamboo (Phyllostachys nigra) or varieties of Fargesia.

To grow bamboo in a container, make sure the container is at least 45cm (18") wide and deep to give the roots room to spread. Use loam-based potting compost such as John Innes No.3. Keep containerised bamboo well watered and fed throughout the summer months. Bamboos like a consistently moist soil and a fairly sheltered spot for the best growth, either in sun or dappled shade.

Fuchsias are a colourful and rewarding shrub Image: Image: Natashamamaska / Shutterstock

• When should Fuchsias be cut back?

Fuchsias are best pruned in the spring - cut any weak spindly growth right back to the base.

Well established plants can have the oldest stems pruned out when the fresh buds begin to break, keeping an open framework. Reduce remaining stems to restrict their vigorous growth to the space available and tie the stems in to their support.

• What is the best time to plant out cobnut saplings?

Hazel cobnut sapplings can be planted out any time before the end of March, so long as the ground isn't frozen or waterlogged. They are very hardy and should establish fairly quickly.

• Should a Oleander plant hurt by frost be dug up?

Oleanders are sensitive to frost and can struggle after a hard winter or two. So long as the roots have not been killed by the cold it is worth trying to regenerate it.

Oleanders can tolerate hard pruning and often come back bigger and better with more flowers, as they flower on new growth. Leave until late summer or autumn, then reduce the branches by half and remove an damaged ones entirely.

Spread a thick mulch of well rotted manure or compost around the base of the plant to feed it and conserve moisture at the roots. It may take a year or two to fully recover.

During winter cover it with a fleece on frosty nights.

Remember to wear protective gloves and long sleeves while handling this plant as all parts including the sap are highly toxic and an irritant to skin.

• What is the best way to grow Wisteria up a wall?

The Chinese Wisteria (Wisteria sinensis) is most commonly grown but the Japanese Wisteria (Wisteria floribunda) is also widely available.

Both are quite fragrant, however, Chinese Wisteria often has a stronger scent. Its Japanese cousin has longer, showier flowers, although it can take a few more years to become established and may be slightly slower to flower.

A sheltered south facing position is ideal for Wisteria as the flower buds can be damaged by hard spring frosts in colder aspects.

Grow Wisteria in a sunny or semi-shaded position in any moist, well drained soil.

Prior to planting add plenty of well rotted manure or garden compost to the soil. Remember that Wisteria is a large and long lived climber so it will require permanent sturdy supports for its growth. Attach strong wires with vine eyes to your wall prior to planting.

After planting, feed and water your plant regularly until it is fully established.

Prune Wisteria in July and again in February. During the first two years, prune to create a framework of permanent stems. Tie in selected lateral shoots to sturdy supports and cut back unwanted growth. Once the desired framework has been created, continue pruning twice a year to contain the plants growth within its allotted space.

• What size can I grow Tree Peony to in a container?

Tree peonies can be successfully grown in containers although eventually after 5 or 6 years they will need planting out into a garden bed.

Plant in a container that is at least 30 cm deep and 30 cm in diameter, using a soil based compost such as John Innes No.3.

Peonies like good drainage so it is worth mixing some grit into the compost. You will need to top-dress the container each spring with fresh compost and feed you tree peony during the growing season to ensure abundant flowers and strong growth. Try using a slow-release fertiliser to save the hassle of liquid-feeding every few weeks.

Make sure the compost is kept moist, especially during long hot spells.

Azaleas brighten any garden with their happy blooms Image: Image: canghai76 / Shutterstock

• What is the best way to keep potted Azaleas over winter?

Most azaleas are perfectly hardy so you can stand them outside for the winter and they should be fine.

If they are very young plants they may appreciate a sheltered position beside a wall or fence.

When planting out, they will require an acid soil. If your soil is not acid then you may need to grow them in containers in the long term.

• What Shrubs can be planted in shady areas which will produce flowers in the spring or summer for bees and berries in winter for birds?

Cotoneaster is ideal as it’s spring flowers are attractive to bees and other insects, and it’s autumn berries are eaten by several bird species. Chaenomeles, Symphoricarpos and Pyracantha are also attractive to both birds and bees.

Leycesteria and Holly also produce berries that attract birds (make sure you have a female holly with a male nearby to pollinate).

Sarcococca provides a good source of winter berries when there is little else for birds to eat.

Under planting with nectar-rich herbaceous plants such as Heuchera or Pulmonaria provides valuable spring flowers for bees.

All of the plants mentioned here are suitable for shady or semi-shady positions.

How do you hybridise Viburnums?

Viburnum can be hybridised. It will be quite a few years before you see the fruits of your labour though.

To hybridise Viburnums it’s best to select particular flowers from specific parent plants before they open and cover them with a bag to prevent insect pollination. Once opened, hand pollinate them. Once pollinated mark the flowers with a piece of thread or wool to identify the seed heads to collect later in the season. By hand pollinating, you will know the parentage of any offspring raised.

• When is the best time to prune a Tree Peony?

Tree peonies generally respond quite well to pruning. The best time to prune a Tree Peony is in late winter or early spring, just as the buds begin to swell.

If the Tree Peony was planted in the last two years only take out occasional dead stems while it is still establishing. Cut stems back to a live bud or to just above ground level.

If the Tree Peony is well established but misshapen, prune each stem back hard to about 15cm (6") from ground level to encourage new stems to be produced. It is important that hard pruning should be spread over a number of years, pruning back just one main stem per year. After several years a misshapen Tree Peony should develop a better shaped framework of stems. This process risks the loss of some flowers but the end result will be worth the sacrifice!

• When is the best time to prune Pyracantha to maintain a good showing of berries?

Pyracantha, As with other evergreen shrubs are generally best pruned in mid-spring. They will lose some berries or flowers regardless of the time of year pruned.

Wayward shoots that need removing can be cut out completely, back to where they join the main branch.

To reduce the size of the plant, do a general prune, cutting shoots to within two or three leaves of the main branches. This ensures some older wood remains as Pyracantha flowers on wood that is one or more years old.

• How do you encourage Wisteria to flower?

There are several reasons why Wisteria can fail to flower. Summer drought is often a cause, lack of nutrients and incorrect pruning.

Containerised plants are particularly susceptible to drought. Ensure Wisteria is well watered from July to September - this is when the flower buds for the following spring begin to develop.

Occasional high potash feed will also encourage flower bud development.

In winter, cut back the side shoots to within two or three buds from where they join the main branches. These will form flowering spurs that will bear this year’s flowers. In summer, tie in the main branches to their supports. Two months after flowering, cut back the side shoots to about 6 buds from the main branches.

Banner image: Image: Ellita/ Shutterstock

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