Some plants are generous with their flowers, blooming for months rather than weeks. Many continue right through summer and into autumn because they fail to set seed. This usually happens for two reasons.
Some plants are sterile. Even when bees visit in numbers, the flowers cannot be pollinated. This often occurs when two closely related species hybridise. Their pollen is incompatible, so no viable seed is produced. The plant responds by flowering again and again, either continuously or in fresh flushes.
In other cases, the shape of the flower is the key. Fully double blooms often contain little or no pollen or nectar. Their tightly packed petals are hard for pollinators to reach, but the flowers last much longer than single forms. This is why breeders favour double roses, primroses, dahlias and peonies.
Try these blooming beauties to bring the colour even when the sun isn't shining…
1. Nepeta ‘Chettle Blue’: This upright catmint flowers from May until October and was the standout plant in the RHS trial from 2018 to 2021. Deep blue flowers sit in purple calyces, giving a dusky look against sage-green foliage. It is highly attractive to bees and the fading flowers remain tidy. Hardy and long-lived, it forms a substantial clump that keeps going into autumn. H: 75cm
2. Helenium ‘Sahin’s Early Flowerer': A bright helenium with orange flowers and brown centres, each slightly different from the next. It lights up a sunny border from June through to November. The main flush comes in summer, followed by repeat flowering. Deadheading encourages quicker reblooming, though the plant will flower again without it. H: 90cm
3. Dianthus ‘Gran’s Favourite’: A double pink with bold magenta lacing on a pale blush background. Given an open, well-drained position, it flowers for weeks on end. Introduced in 1966, it looks traditional but is easy to grow and widely available. Like many dianthus, it is scented and suits the front of a border or a sunny container. H: 30cm
4. Aster frikartii ‘Mönch’: This European hybrid aster starts flowering in July and carries on into autumn. Large lavender-mauve daisies are held on slightly floppy stems. Raised in 1918 using Aster amellus and Aster thomsonii, it copes well with dry conditions and suits a sunny spot. H: 90cm
5. Geranium ‘Patricia’: One of many sterile, long-flowering hardy geraniums. This clump-forming variety has dark-eyed magenta flowers from July onwards. Unlike sprawling types, it stays neat and also tolerates bright shade. Other hybrids include ‘Dragonheart’. H: 90cm
6. Achillea ‘Moonshine’: A sun-loving achillea with finely cut silver foliage and domed heads of acid-yellow flowers. Blooming begins in May and continues until October. It is valued for its exceptionally long flowering season. To keep it vigorous, it needs propagating every four to five years before the centre becomes woody. H: up to 90cm
7. Verbena officinalis ‘Bampton’: Named after the Devon town, this dark-leaved verbena produces heads of tiny lavender flowers from summer to late autumn. It thrives in dry soil or against a warm wall and will self-seed freely. Well suited to informal planting, it often pops up in paving and gravel. H: 60cm+
8. Anisodontea ‘El Rayo’: This shrubby African mallow is almost always in flower and keeps much of its foliage through winter. Bright pink blooms with a darker centre are carried on an open, airy framework. It needs a sheltered site and is best backed up with summer cuttings, as it is short-lived. H: up to 120cm
9. Rudbeckia fulgida deamii: A neat, well-mannered yellow daisy with brown centres. Flowering starts in late July and continues into autumn without fading. The foliage is strong and tidy, and this form does not spread like many other yellow daisies.H: 90cm
10. Hylotelephium ‘José Aubergine’: A rich, dark sedum with coloured foliage from early spring. Upright stems carry deep red to pink flowerheads that deepen to chocolate brown as autumn arrives. Like all sedums, it copes well with dry conditions and is particularly resilient. H: 50cm
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