THE SUMMER STUNNERS
Perky penstemons will bring long lasting dazzle to your scheme
Many of our best-loved summer blooms come from the americas — dahlias, petunias and fuchsias. Penstemons, though less familiar, are just as good. Related to foxgloves, penstemons produce spikes of hanging tubular flowers from June to late autumn. But unlike foxgloves, they develop perennial clumps.
you can plant containerised penstemons any time between april and early autumn. They’re easy to grow and if not yet in flower, soon will be. Hayloft Plants (hayloft-plants.co.uk) have a good range.
apart from elegance, the penstemon’s great virtue is persistence in flowering. Mature plants constantly produce new flower stems as long as you keep removing spent ones. a puny specimen planted in May becomes a generous clump by august and flowering can continue until late October.
Some varieties are fully winter hardy. Others get through most winters with little protection.
Lay fleece or a compost mulch over the plants in autumn, or keep potted plants in a cold frame. Take a few cuttings, too — in case of winter losses.
The world knows only 22 foxglove species but there are about 250 penstemons, all from the americas.
Some are worth growing, but the hybrids flower for longer and make a prettier show. apart from white, colours run through reds, pinks, purples and almost to blue.
TOUGH BEAUTIES
HARDINESS varies, but there’s a useful rule of thumb. Varieties with narrow leaves and slender flowers tend to be the toughest. Those with broader leaves and wider flowers are more tender. among modern hybrids, the Pensham series produce whitethroated flowers in red, amelia Jayne; plummy pink, Laura; and purple Czar. if you prefer scarlet, try Red Riding Hood and purple, Plum Jerkum.
all varieties mentioned so far are borderline tender. They’ll get through a gentle winter but keep them protected.
Hardier varieties include Sour Grapes whose purple flowers carry a greenish sheen. i used to grow the narrow-leaved pink variety evelyn, but if you can’t find that, Hidcote Pink is nearly as hardy.
among reds, these veteran varieties are still unbeaten. Firebird — or Schoenholzeri — has mid-size, scarlet blooms and amazing vigour. andenken an Friedrich Hahn — old name Garnet — is similar but with wine-red flowers.
VERSATILE PLANTS
PENSTEMONS do best in fertile, well-drained soil, but can also cope with heavy clays or sharp-draining sand. Keep them watered on thin soils and if you can, compost beds each year. Penstemons also make excellent pot plants. Use a roomy container that drains well and is in a sunny position.
do not allow your penstemons to set seed. enjoy the flower spikes but cut each back before the last few blooms drop. each severed stem will then produce new shoots.
When growth finally stops, don’t cut your plants back. Leave them until april, when new basal shoots will grow.
They’re so easy to propagate. Cuttings taken between april and September will root in a few weeks. So if you take some today, the resulting young plants might even flower this autumn.