Variegated lady’s mantle (Alchemilla mollis)
New plants on trial: Top Shrub – Physocarpus Coppertina

New penstemons

Penstemonpenshamczar I’ve just finished writing as piece about new penstemons for The Garden, the members’ magazine of the Royal Horticultural Society. It will appear in the July issue. But I was struck by the fact that most of the penstemon breeding in Britain is of the taller, large-flowered, blowsier types while in North America work is more concentrated on shorter, hardier, smaller-flowered varieties. But each country could, I think, grow more of the plants raised on the other side of the Atlantic.

Penstemonpinkdawn It’s true that the flamboyant recent British introductions – mostly in series with names such as Pensham, Seas, Volcano, Ice Cream and the more compact Patio are not even hardy in all of Britain so are certainly tender by American standards – many may be rated zone 7, most of Britain is zone 8, but excessive moisture in the fall and in the spring snowmelt can also be fatal. The answer is to grow them in North America as temp-perennials, seasonal flowers for a spectacular summer display in borders or containers. Then either take cuttings and overwinter them young plants frost-free or simply replace them the following year.

In Britain, Penstemon digitalis ‘Husker Red’ is widely grown, and new hybrids of it like the lovely ‘Pink Dawn’, bred at the Chicago Botanic Garden, and sumptuous ‘Dark Towers’, bred by Dale Lindgren at the University of Nebraska (not yet released), will be too. Look out for them. But the shorter, hardier introductions from US breeding are not often seen.Penstemondarktowers

The Mexicali Hybrids, well known in the US are rarely grown, likewise the Saskatoon Hybrids. Dan Heims says that his five creations of this type - ‘Crushed Grapes’ (deep purple), ‘Party Dress’ (pale pink, ‘Pink Chablis’ (salmon pink) and ‘Sweet Grapes’ (lavender purple) plus ‘Coral Carpet’ (coral pink, not yet released) will take -35C. Great for the front of a sunny, well-drained border on either side of the Atlantic. And no worries about winter cold.

Penstemoncoralcarpet In fact, it turns out that even in the US these neat and prolific newcomers are not as popular as perhaps they deserve. I have to say that the two small plants that came to me by mail were far too wet and died as a result. And Dan says keeping them from getting too wet is crucial. But they're so colorful and so prolific… I’d certainly give them another try.