See my wisteria gallery courtesy of photo-sharing on flickr

https://www.flickr.com/photos/25977589@N07/galleries/72157647630069894/

These last two years have been a roller-coaster ride for wisterias. Reports of wisteria scale insect started to occur, being first identified in Wimbledon. Fortunately this insect cannot fly so it's spread has been slow, a Cambridge college has been infected but so far no reports in Oxford.

April/May 2011 was frost free and with out rain, and these were the perfect conditions for the Chinese wisterias to flower. 2012 looked like being a year hosepipe bans and March was warm and sunny. Then came frost and rain and the Chinese plants that had done well the year before lost their flowers to the weather. Simlarly the Japanese varieties suffered frosted buds, but where they escaped the cold their flowers were exceptional, perhaps benefitting from the wet start to flowering season.

Then as the poor summer continued many owners have had their plants hard pruned to try and get light back into their houses after the summer that never was.

Wisteria

Wisteria sinensis is the Chinese Wisteria and it’s introduction was a by-product of the tea trade. Traders at Canton admired the prolific blooms of a wisteria in the garden of a Chinese merchant and enquired whether they could have some young plants to send home. This was agreed, unlike the tea plant, which had to be smuggled out by Robert Fortune. In 1816 two wisterias reached our gardens and hence nurseries, it was so sort after that plants sold for six guineas! By 1835 that price had dropped to five shillings and it is believed that most of the Chinese Wisterias in Britain are vegetative descendants of those first imports. Flowers are born before the leaves in late April and early May. W. sinensis is best planted on a sunny wall where the residual heat will protect the flowers from frost. W. sinensis is very tolerant of winter pruning and it is for this plant that the three bud rule was developed. Prune all the new growth back to three buds in January except those stems which are needed to carry the plant onto the next section of wall or pergola.














Wisteria floribunda came into our gardens via the Dutch who were the only Europeans to trade successfully in Japan. These plants often take seven years to flower, so were not as common in our gardens, but in recent years this has changed. Also they must be planted in full sun preferably on a pergola or at least a south facing wall. Refrain from feeding and watering which aids the production of leaves and not flowers which are born in mid to late May so are less susceptible to frost damage. Wisteria floribunda has many more flower forms and colours, has better foliage and autumn colour. A better plant on paper, but in the garden you need a much longer time scale to grown them to full effect and exactly the right conditions. You just don’t get the spur development from floribunda as you do from sinensis. So I look to prune them more during the growing season, then just give them a tidy up in the winter adding extra ties, taking out any deadwood and long stems that have been missed. The plant in the picture is Wisteria floribunda ‘Shiro Noda’

The first wisterias to reach Britain came from America from 1724 onwards and are best represented as Wisteria frutescens. Neither as strong growing or free flowering as their oriental cousins, but have some admirers for their attractive bark and flowers born late June to August. Other species of interest are Wisteria japonica with small pale yellow flowers born July and August. Wisteria venusta is very vigorous white wisteria, again from Japan. Finally there are hybrid wisterias such as W. x formosa, a cross between sinensis and floribunda. Named wisterias could be a species or hybrid.