10 AGM shrubs for containers

Growing shrubs in containers can provide a useful foil for temporary plantings, or they can be a feature in their own right. Graham Rice discovers which are best-suited to life in pots

It’s important to choose shrubs for containers carefully. Not all shrubs are suited to life in a container, even a large one. These winners of the RHS Award of Garden Merit are all good choices, and they have a long season of interest, which is important as containers tend to be sited in prominent positions. Heights are not given as plants will vary with the size of the container and how well they’re fed.

H1 - H7 indicated the new hardiness ratings

Full details of hardiness ratings (510kB pdf)

Rosa Munstead Wood (‘Ausbernard’)

This compact rose, one of the shorter of David Austin’s English Roses, is ideal in a container. It has a long flowering season, its large sumptuous flowers are deep crimson, a little paler on the backs and as the petals mature, and the powerful fragrance has a fruity note. In addition, the new leaves are an attractive reddish bronze shade. Best in sun. H6.

Luma apiculata

Although developing into a large shrub or small tree when planted out in the south west, this attractive evergreen enjoys container life. The neat, dark green, pointed leaves are the perfect backdrop for the masses of late season white flowers, which develop red fruits that mature to black and have an appealing sweet flavour. The cinnamon-coloured bark peals attractively. Sun or partial shade. H4.

Rhododendron ‘Dopey’

Many rhododendrons are too large and too boring when not in flower to be grown in containers, but hybrids of R. yakushimanum, ‘Dopey’ is a representative example, are ideal. Its heads of vivid red flowers almost hide the leaves but, after dead heading, its attractive mounded shape and glossy leaves are appealing all summer. Ericaceous compost is needed, of course, along with some shade. H4.

Prostanthera rotundifolia

This lovely evergreen is less hardy than most of my choices but its container can be moved to a sheltered place or a conservatory for the winter. Dense growth and very small leaves set off the purple summer flowers, shaped rather like those of a small penstemon; they open in such numbers as to smother the plant. The pink form, ‘Rosea’, also has an AGM. Best in sun. H3.

Pittosporum tenuifolium ‘Silver Queen’

Another example of a large evergreen shrub that enjoys container life surprisingly well. The small, slightly wavy-edged leaves have creamy edges and an overall silvery caste and the plant’s year-round attraction is augmented by small clusters of honey-scented, chocolate-coloured spring flowers. If necessary, plants can be kept to a given size by thoughtful removal of branches for indoor arrangements. Sun or some shade. H4.

Pieris japonica ‘Prelude’

Like kalmias and rhododendrons, pieris need lime-free soil so many gardens cannot grow them but, when planted in containers, they thrive in ericaceous compost. ‘Prelude’ is naturally more compact than most. Its pendulous sprays of pure white flowers, which develop very few inelegant brown pods, are shown off well by the dark foliage and its new foliage emerges bright pink. Best in partial shade. H5.

Kalmia latifolia ‘Little Linda’

Kalmias are lime-hating evergreens with a dramatic burst of June flowers. The compact ‘Little Linda’ has generous clusters of bright red flower buds which open to white then develop a strong pink flush as they mature. Unlike most dwarf forms, the leaves are half the size of taller types so everything is in proportion. Ideal in ericaceous container compost in full sun or partial shade. H6.

Hebe ‘Pink Elephant’

A neat and very hardy hebe. The small dark evergreen leaves are broadly edged in creamy yellow, with pink tips to the shoots, and the whole plant becomes tinted in pink and then burgundy in cooler weather. What’s more, there are also spikes of small white flowers in summer. Makes a very attractive individual specimen. Best in sun. H4.

Daphne × transatlantica Eternal Fragrance (‘Blafra’)

Impressive fragrance, neat, semi-evergreen growth and white flowers with pink tubes make this a valuable shrub but it also has the rare feature of producing flowers not just in the shoot tips but from the leaf joints of the new growth to extend the season from spring into the autumn. Ideal in a prominent sunny position for both flowers and fragrance. H5.

Acer palmatum var. dissectum ‘Crimson Queen’

Many of the smaller Japanese maples are good in containers, in spite of hating prolonged dry summer conditions. The leaves of ‘Crimson Queen’ are very finely cut to create a lovely lacy effect but its special feature is that, unlike most deep red cutleaf maples, it keeps is colour from spring until the leaves develop scarlet tones in autumn. Best in light or partial shade. H6.

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