May is always such an exciting time in the garden because the active growth of plants really starts to take off, and buds give glimpses of the colour to come. May is also a good time to start planting perennials for summer colour, as the soil will have warmed up but the weather is generally still cool, giving plants a good opportunity to establish themselves in their growing locations before hot weather arrives. To get the most out of your borders, invest in perennials with long flowering periods, as many will keep giving colour and interest from mid-summer well into the autumn.
1. Rudbeckia – Coneflowers/Black-Eyed-Susan
These cheerful daisy-like flowering plants pick up from late summer, and many keep going through September and October, before dying back in the winter. They tend to come in warm colours of yellow, orange and red, so lend themselves well to autumnal floral arrangements.
2. Symphyotrichum – New England Aster
Once part of the Aster genus, these herbaceous perennials are now formally known by a different name. However, they still provide ample supplies of glorious colour from late summer to early autumn. They are often available in shades of blue, purple and pink and are best suited to the middle or back of a border as they grow quite tall.
3. Crocosmia – Montbretia
Another perennial that picks up in late summer as other plants finish flowering. There are a wide range of Crocosmia available on the market in colours of orange, red and yellow, and, once established, these plants grow well many spots, as well as in containers. They do particularly well in full sun with reasonably moist soil. The flag-like flowers add contrast and vibrant colour to mixed borders.
4. Persicaria – Knotweed, Red Bistort
Persicaria can be evergreen or herbaceous and make good additions to flowerbeds and borders as their upright spikes of tiny flowers come continuously through the summer and into the autumn. In addition, they are vigorous growers and provide efficient ground cover in moist, boggy soils.
5. Pennisetum ‘Fairy Tails’ – Fountain Grass
All ornamental grasses make fantastic additions to gardens, but this particular grass produces many wonderful soft flowers that fade from pink to beige over the course of the season. As well as a long flowering season, grasses also offer additional texture and movement to borders.