The quiet Americans
Most people know and grow weigela. Since they were first introduced from temperate East Asia in 1845 they have continued to blossom in our borders. The selectors and hybridisers have produced a wide range for our enjoyment. They can vary in height from barely two to twelve feet. Flower colour can vary from white through all the shades of pink to dark red. There is a yellow one (Weigela middendorffiana) and a few that have both white and pink flowers at the same time eg 'Darts Colour Dream '. The leaves can be just as exciting. As well as green you can have purple and gold and a whole range of combinations in variegation. In short they are so good that few people bother with their quieter American cousins: Diervilla.
In fact they are so closely related that weigela used to be included in the genus Diervilla, but there are clear differences. The flowers, which are large and symmetrical in weigela, are two lipped in diervilla. They are always yellow and are borne on current years wood. In weigela they are borne on side branches on year-old wood. Diervilla are also much more modest shrubs, seldom reaching 5 ft, but spreading to at least that width via suckers.
There are three species, called bush honeysuckles in the USA. Diervilla lonicera is the most northerly growing. It has mid-yellow flowers that deepen in colour with age. D. sessilifolia is the most common in cultivation and has sulphur yellow flowers. D. rivularis is very similar to sessilifolia, but has lemon yellow flowers. It is only available in the UK as the selection 'Troja Black'. There is a hybrid between sessilifolia and lonicera called x splendens, which is also relatively easy to obtain. More recently two selections of sessilifolia have been available: 'Butterflies' which is smaller leaved, more upright and bears tighter flower clusters and 'Cool Splash' which is a very attractive, variegated form with white edges to its green leaves which sit well with the yellow flowers.
They are all refined little shrubs, easy to grow in any site that is neither bog nor desert in sun or part shade. However with the exception of 'Cool Splash' which glows out in part shade, to really appreciate them they need a fairly sunny site, for their real beauty is in the colouring of the leaves. They are well bronzed when they emerge in spring, and if grown in sun, this colour deepens and last through the season until reddening before falling in the autumn.
Diervilla will never replace weigela, but if you have a little space for something a bit different, think of trying one of the Quiet Americans.
First published in the Shropshire Group Newsletter, January 2012
and subsequently in Cornucopia Issue 31.
© Copyright for this article: Joe Sime
This article was taken from a copy of Cornucopia that was published in 2013. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.