September

Pulsatilla alpina subsp. alpina is a charming form, with white flowers, the outer segments flushed with bluish-purple. A favourite for collectors, they have a protracted flowering period and followed by attractive seed heads, they are showy, long-lived and reliable plants with a lengthy period of interest.

Venerating a former plant curator at the Royal Botanic Garden in Edinburgh, Scotland, 'Ron McBeath' is a beautiful new semi-dwarf cultivar. This diminutive potentilla repeat-flowers for months, sending up wands of rosy carmine flowers even in shade. It outlasts other potentillas by far.

Potentilla 'Helen Jane' is a beautiful new semi-dwarf cultivar that displays gorgeous crimson-eyed, bright pink flowers, with petals that are attractively crinkled just like crepe paper. Flowering over a long period, new buds open repeatedly in a long succession, from late June to September.

Collected at altitude in Japan and introduced in 2006, Polemonium yezoense 'Purple Rain' is one of the best new introductions in recent years. With bronze-purple lacy foliage, dark stems and violet-blue flowers, it is the darkest flower form of Polemonium available.

The white form of the lovely Jacobs Ladder, named after the slender, fresh green leaflets arranged like the rungs of a ladder. Blooming in late spring to early summer, the bright foliage and white flowers will brighten shady locations. Both the flowers and the attractive ferny foliage are excellent for cutting.

The physostegia has prolific dazzling tubular flower spikes which are arranged on distinctly square stems. This oddly named perennial is perfect for the middle of a mixed or herbaceous border. The flowers are on swivels that can be bent right or left on the stem - a useful feature for floral displays.

Tall garden phlox are a beauty to behold, the large, dense flower clusters, produced in abundance during summer. Phlox Hybrids Mix is a perennial, cultivated strain. The colours are wonderful, the sweetly fragrant, evening scent is captivating and they are very easy to grow.

Phacelia is a very attractive plant and one with a variety of uses. Very rich in both nectar and pollen, it is listed as one of the top 20 honey-producing flowers for honeybees. It is ideal for a wildlife-friendly planting scheme and makes a wonderful green manure.

Persicaria orientalis ‘Cerise Pearls’ is a new, modern-day variety that grows to a more manageable height of 100 to 140cm . Tall enough to give the same airy effect, yet so much easier to place in the garden. From August to October the whole plant is spectacularly draped with long, dangling, velour-like cerise tassels.

Russian Sage is one of the great garden plants of all time, but if you've been frustrated by their floppy nature, this new variety will be a welcome addition. Growing to about 60 to 75cm tall, Perovskia atriplicifolia 'Taiga' is also the first Russian sage available as a first year flowering perennial.

Penstemon barbatus 'Twizzle White' adds a graceful twist to the garden. A first year flowering perennial, that is hardy and vigorous, it boasts twice the length of flowering stems, giving longer, more elegant wands for the vase while preserving the natural elegance of Penstemon barbatus.

Awarded the Fleuroselect Gold Medal for striking colour, plant habit, and flowering performance, Penstemon barbatus 'Twizzle Scarlet' is a first year flowering perennial that will add height and high-impact colour to the border, giving superb flowering performance from mid to late summer.

A winner of both an AAS and Fleuroselect Awards, Penstemon ‘Twizzle Purple' is a first year flowering perennial that boasts twice the length of flowering stem. Strong, trouble-free plants produce trumpet shaped magenta-violet blooms that flutter all along tall, slender stems.

Penstemon barbatus 'Twizzle Coral' adds a graceful twist to the garden. A first year flowering perennial, that is hardy and vigorous, it boasts twice the length of flowering stems, giving longer, more elegant wands for the vase while preserving the natural elegance of Penstemon barbatus.

Awarded a Fleuroselect Medal for striking colour, plant habit, and flowering performance, Penstemon barbatus 'Twizzle Blue' is a first year flowering perennial that will add height and high-impact colour to the border, giving superb flowering performance from mid to late summer.

Pennisetum alopecuroides var. viridescens has broader leaves and darker flower heads than the regular species and, growing to around 60cm tall, it is also slightly smaller. It has graceful smoky purple-black plumes that contrast nicely with the slender arching, glossy, deep green foliage.

Pennisetum alopecuroides is an especially appealing species, it changes its appearance and colour throughout the growing season. In late summer graceful fountain-like plumes emerge in profusion, they slowly change colour to a blend of green, soft pinks and light-colored maroons before maturing to light tan.