• 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

H1 – H7 indicates the new RHS hardiness ratings

Full details of hardiness ratings (510kb pdf)
 

Rudbeckia fulgida var. sullivantii ‘Goldsturm’

One of the most widely grown of the yellow daisies, this neat, colourful and long flowering perennial blooms for a long season from July to October. It also has the great benefits of deep yellow petals with a rich, slightly orange tint surrounding a contrasting purple-brown eye. Dependably self-supporting, ‘Goldsturm’ is happy in most soils in a sunny site and is good for cutting. 75cm (30in), RHS hardiness rating H7.

Argyranthemum ‘Jamaica Primrose’

This marguerite is old favourite, making a larger plant than many more recent introductions and also with consistent, summer-long flowering. Opening in bright yellow and fading slightly as they age, unlike the others in this selection the bright daisies are carried on bushy, slightly woody plants that need frost protection in winter. Ideal in sunny borders and large containers. 75cm (30in) RHS hardiness rating H2.

Solidago ‘Goldenmosa’

An old favourite introduced in 1949, in August and September huge numbers of tiny yellow flowers open in large cone-shaped flowerheads. This is an upright plant, and is a dependable border perennial as well as a useful cut flower; cut the stems when about a third of the flowers are open and always use a flower food. 75cm (30in) RHS hardiness rating H7.

Silphium perfoliatum

An imposing perennial, each large oval and dark green toothed leaf is fused into a cup where it pairs with its opposite neighbour and collects moisture after rain; this is a bold plant long before the flower buds open. The 8cm (3in) yellow flowers open In August and September – the petals slightly are paler than the eye and with the each anther contrastingly tipped in black. 2m (6ft 6in) RHS hardiness rating H7.

Helenium ‘Sahin’s Early Flowerer’

There’s something very refreshing about a daisy that you expect to be yellow – but which isn’t. Every other plant included here, except the Argyranthemum, comes only in shades of yellow so the soft red of ‘Sahin’s Early Flowerer’, with only its hint of yellow at the tips is a treat. 80cm (31in) RHS hardiness rating H7.

Inula magnifica ‘Sonnenstrahl’

A bold perennial with large elliptical leaves that can reach 25cm (10in) long. In June and July the 15cm (6in) flowers are borne on purple tinted stems. Each flower is made up of a generously-filled ring of very slender, bright yellow rays surrounding a slightly darker eye. ‘Sonnenstrahl’ was selected by the German nurseryman Ernst Pagels for being unusually prolific. Best in damp soil. 2m (6ft6in), RHS hardiness rating H7.

Heliopsis helianthoides var. scabra ‘Benzinggold’

Prolific and easily manageable, these self-supporting relations of the sunflower carry semi-double flowers from July to September. The blooms are golden yellow and have three rows of ray florets, which develop a richer tone around the orange eye. Drought tolerant once established, but happiest in good soil, plants can be cut back in late May to reduce the flowering height and encourage many more, (though slightly smaller) flowers. 1.2m (4ft), RHS hardiness rating H5.

Helianthus ‘Monarch’

This is a tall and dramatic perennial sunflower featuring flowers which are usually 15cm (6in) across, but which can be almost twice that if the side shoots are nipped out. In bright, golden yellow with a dark red centre which yellows as it matures, ‘Monarch’ is at its best in September and October. Often requiring support, it may become uncomfortably vigorous and so need controlling. 2.5m (8ft), RHS hardiness rating H4.

Helenium ‘Butterpat’

Its crowded ring of slender, bright yellow rays, which are the same shimmering shade underneath, surround a pale green eye which quickly matures to the same colour as the rays. Very prolific, and usually opening in August for a long season, it has a tendency to lose its lower leaves and so benefits from being sited behind a shorter, bushier plant. Raised by Alan Bloom and introduced in 1960. 1.2m (4ft) RHS hardiness rating H7.

Coreopsis verticillata ‘Grandiflora’

One of the tallest cultivars of this very tough and hardy, slender-leaved perennial, the July to September flowers have more impact than those of some other cultivars – as the petals of the flowers overlap at the edges to create a fuller effect. ‘Grandiflora’ is also taller than the other AGM cultivars ‘Old Timer’ and ‘Zagreb’ and so better suited to cutting for large cottagey arrangements. 90cm (3ft) RHS hardiness rating H5.
 


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