• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

10 AGM container perennials

For gardeners who appreciate a bolder and longer lasting presence, container plants are ideal. Here are 10 greats

H1 - H7 indicate the new hardiness ratings

Full details of hardiness ratings (510kB pdf)
 

Ajuga reptans ‘Catlin’s Giant’

A shade lover for the front of a mixed container, ‘Catlin’s Giant’ combines impact with the tendency to trail over the edge and soften the lines of large pots. In spring, spikes of deep blue flowers, emerge from amongst large darkly bronzed leaves, the foliage becoming greener with age but the new leaves bronzed. Usually needs young pieces replanted after three years. Vigorous, may trail to the ground then root. 20cm (8in) H7

Brunnera macrophylla 'Jack Frost'

As a specimen in a 25cm (10in) pot, or as part of a mixed planting in a larger container, the brightly silvered foliage of ‘Jack Frost’ brings light to the shade in which it is happy to grow. The bold, roughly textured, heart-shaped leaves make an ideal background for the clouds of small, blue forget-me-not spring flowers. Takes some drought, but will burn if drought is combined with too much sun. 38cm (15in). H6

Dianthus 'Gran's Favourite'

The intricate patterning of this prettily fringed flower, with its blood red heart, repays close inspection so is ideal for a sunny container on the corner of the patio or by the door – where its rich fragrance, and its grey foliage, will also be appreciated. Introduced in the mid 1960s, its stems can be weak so a little very discreet support – or the support of container neighbours - will be valuable. 35cm (14in) H6

Erysimum 'Bowles's Mauve'

This classic perennial wallflower appreciates sun, and some close neighbours to fill in the space at the base where its leaves tend to drop off. That greyish evergreen foliage crowds the strong stems which are topped by spikes of pale mauve flowers which darken as they age. May become top heavy eventually, and will usually need replacing after three years. Flowers almost all the year round and very rarely sets seed. 75cm (2 12 ft) H4

Read about Bowles' Corner at RHS Garden Wisley

Euphorbia Redwing (‘Charam’)

A compact and valuable evergreen, mainly for winter and spring, which also brings colour the year round. Its new shoots emerge rich red then the foliage matures to red-tinted, dark green held on bright pinkish-red stems. It looks lovely rimed in frost. Then its deep chartreuse flowers open in full and compact heads transform the plant in spring. Cut out the flowering shoots in early summer. Surround with scillas. 40cm (1ft) H5

Geranium Blue Sunrise (‘Blogold’)

One of the best of all perennials for a container, especially in a smaller garden, it also makes splendid specimen in a large clay pot. In March, new shoots emerge with yellow leaves brightly edged in red; chionodoxa make ideal companions. Then, as the shoots develop and the foliage matures, its bright yellow colouring is like a shaft of sunshine. Finally, all through summer, there’s a long season of blue flowers. Lovely. 40cm (112 ft) H7

The Plantsman: Painting hardy geraniums

Hakenechloa macra 'Aloaurea'

When Adrian Bloom first showed large pots of mature variegated hakonechloas at Chelsea twenty years ago or more, it was a new idea. Now, the delicate fountains of white- and yellow-striped, green foliage are recognised as one of the most lovely features for containers. Developing slowly but surely, ideal in partial shade, maturity is worth the wait. Regular watering and feeding is helpful. Or cheat and plant three in one pot. 35cm (1ft) H7

Heuchera 'Purple Petticoats'

Many heucheras are good in containers, but those with a little subtlety and some intriguing colouring are ideal in pots along paths or by doorways where they can be seen up close. The young foliage of ‘Purple Petticoats’ is bronzey red, the mature foliage is bronze-tinted green, but the edges of each leaf are so dramatically ruffled (increasingly so in cold weather) that the bright red-purple undersides spark through. Cream flowers. 60cm (2ft) H6

Garden design: urban garden plants

Hosta 'Fire Island'

Most hostas are good in containers, from big bold specimens to miniatures, but ‘Fire Island’ is another perennial where looking closely is well repaid. The yellow-green leaves with their distinct, symmetrically arranged veins, are supported on bright red stems. But the colouring in the stems is extended into the leaf itself in the form of a line of bright red speckles. Lovely with a bright yellow carpet of Lysimachia nummularia ‘Aurea’. 35cm (1ft) H7
 

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