Wisteria

In Japan, China, and Korea Wisteria naturally grows through trees in moist woodland and by streams, the woody stems twining up to the light.  I have read of tresses of the lilac flowers being seen all down wooded hillsides in Japan, something I'd like to see for myself in time.
Some wisteria are already in flower in London and now is a good time to visit nurseries to choose the blossom colour you want.  There are many lovely varieties - white, pink, lilac, purple - but you can't really rely on a word description to necessarily match your idealised version of the blooms.  Neither modernist nor minimalist it's still a classy plant, originating in Asia, that epitomises the English country garden, and seen here on a Georgian townhouse. The greyish gnarled stems imply a long-established history when formally trained on a building. Less often in the UK (due to lack of space, maybe, and because we also like other climbers like clematis and roses) but more common in Japan is to see the plant trained on sturdily built pergolas where the racemes (tresses of flowers) can hang down.  At Giverny, Monet's garden in Normandy, a wisteria walk on a bridge means the flowers are reflected in the water to stunning effect. Wisteria can also be allowed to naturally scramble its nine metres or more through a suitably large and strong tree.

Wisteria needs full sun or partial shade. It is a member of the pea family, Papilionaceae - the five petals of its flowers, just as those of peas and beans, resemble the four wings and body of a butterfly when opened flat.  As most other members of this family, the roots form nitrogen-fixing bacterial associations, so plants don't really need a lot of fertiliser other than a normal mulch of organic material (one rich in leaf mould - think woodland floor - would be ideal).  If you add a high-nitrogen fertiliser, there will be lots of leafy growth at the expense of flowers.  However, potash is needed to get those lovely great droops of flowers.
Pruning is essential to maximise floriferousness (that's a real word used by horticulturalists). As other woody plants that flower before July, flowers are produced on the previous season's growth and you prune after flowering.  In late July or August, shorten the current season's shoots to 30cm (unless they are to establish framework or replace damaged branches). The flower buds form at the base of these shoots. In late winter, towards the end of the dormant period, cut these shoots back to 5 cm or so (not more) of the older wood. The flowering stems will erupt into growth.

urban - over Leylandii  in Lambeth Walk

Oval cricket ground

beautifying a garage

Wisteria floribunda (from Japan - the Japanese for wisteria is 'fuji') twines clockwise; W. sinensis (from China) anticlockwise.  Most varieties for horticultural sales are crossings and re-crossings of these two species and also W. brachybotrys. Scions (shoots) are grafted onto rootstock. Do not plant any grown from seed as you are likely to be disappointed. Plant so that the union is the ground (see here for general instructions about planting a wall climber). After planting prune back the leading shoot to 90cm above the ground. In the first growing season tie in lateral shoots and cut back sub-lateral shoots to two or three buds. During the first winter cut back laterals by one third and sub-laterals by two or three buds. Repeat this pattern for new growth.

I'm lookng forward to my Wisteria client getting years of pleasure from the wisteria we choose and plant together!

Green walls, Green Park

Being queue averse, I abandoned Van Gogh at the Royal Academy and went to look at two green walls planted nearby last year, each in a blast of publicity. At Anthropologie, left, an American shop for women's clothes in Regent's Street, the indoor wall is sustained by UV lights.  It spans three storeys. At the Athenaeum hotel, right, in Piccadilly, the wall clothes one corner of the building.

In both cases the modular planting pockets are visible, salt deposits have accumulated (not so attractive) and some species clearly do better than others.

Green walls are expensive to install and intensive to maintain.  These two examples felt to me as sustainable as annual bedding, and a bit sad. Neither shoppers nor tourists looked at them. 

There is something in green walls, and I want them to work, but I think the difficulty of keeping them looking good will mean they are a passing fashion and unlikely to attract many more corporate commissions.

Across the road, un-designer, unfashionable and  really rather vulgar :) narcissi and cheery blossom brought joy to all in Green Park, left in front of Buckingham Palace, and right, behind the Foreign Office.