PLANTED a wisteria about 18 months ago. The first spring it flowered
on the old wood. I let it grow for the summer to fill the framework.
I cut back some of the old wood in summer and again in winter to
get the spurs, which I thought would flower. Unfortunately, this
time it has failed to flower at all, even on the old woody spurs
that flowered last year and were untouched. It is in a sunny spot
and we get frosty winters so I am perplexed. Has it put all its
energy into growing or is the soil too rich?
older a wisteria gets, the better it will flower. However, you may
experience the odd hiccup in flowering for the first two or three
years. But judicious pruning can improve things and, in later years,
may be essential to control wisteria's sometimes rampant growth.
In summer, around December, cut back all new season's growth to
within three leaves of the main leaders (the old woody growth).
This might seem drastic, especially when you're effectively cutting
off as much as 75% of the leaf coverage. But the stubs you leave
will form the flower buds for next year's display. A couple of months
later cut back the next lot of new growth in the same way. Then
in late winter do the same to any remaining long shoots back and
remove any broken, weak or damaged pieces. If you stick to this
system you should get great annual flowering and your wisteria shouldn't
get out of hand.
Gardener, Issue 206, 2006, Page 37
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.