Gardening with Gael - Penstemons splash colour on gardens

PENSTEMONS: Attractive colourful blooms are always welcome in the garden!

Usually when Touchwood Books send me their monthly (or maybe its weekly) email I give it a cursory glance and manage to resist. That is, until their SPECIALS also become SALE items and then I allow myself a further look. As a result I have new book on penstemons. I discovered penstemons in the ‘Perennials Large and Small’ category in the Parva plants mail order catalogue many years ago. Very little was said about them in that catalogue and my book on bulbs and perennials other than attractive, showy and outstanding performers, prolific display of blooms, and easily grown in any well drained soil.

Their rapid growth and colourful blooms have guaranteed them a place in the garden. I have never given much thought to where I planted them other than that they are great fillers in an herbaceous border and require little care other than deadheading. Last year, in early spring while cutting back a badly overgrown penstemon I noticed small roots growing at the base of some of the leaf nodes. Instead of throwing them all on the compost I potted up a number of cuttings and then, because I had such a pile and couldn’t bear to throw them away I trimmed them and stuck them into a dry crumbly bank I have that has lots of gaps, is steep and difficult to plant and where weeds flourish in the bare patches of ground. 

The penstemons flourished. All summer and into winter they bore their flower spikes of deep purple bell shaped flowers. I was amazed. These plants had continued through the drought, ignored the weeds and filled the gaps. The new book I have bought has explained why.

Penstemons are native to North America and a number of them grow and flower in arid conditions. The author Robert Nold is an enthusiastic admirer of the genus and has 200 species in his garden. He has the same disinclination to spray as I have and believes the right conditions are all a plant needs to be healthy.

The barren conditions often experienced by penstemons in the wild can be replicated here in our sandy coastal gardens. ‘Penstemons’ he says ‘do not need a chocolate cake style soil’ and  I recoiled having just planted some in exactly that – lovely rich soil from my compost bin. I thought they deserved a treat. No, sandy soils, gravel, and well drained loam is all they require. They send their roots down for any moisture and prefer their crowns dry.

Trimming them back in the spring is also important. The plant protects the crown in winter, which, if exposed to frosts or a great deal of rain can be damaged and the plant die. By pure chance that is when I have always pruned them other than deadheading. 

There are many varieties on the market with colours ranging from the deepest purples, blues, reds and magentas to pink, white and combinations of both (white with pink edges etc). Once they are in your garden  propagating them is easy and keeps the plants tidy and compact. I think it is a good idea to introduce new fresh plants from time to time as well. The most reliable varieties include Alice Hindley (lilac blue and white), Appleblossom (pink and white), Blackbird (deep reddish purple), and Maurice Gibbs (red and white).