"The Old OakTree" wrote in message
...
It's been growing on the wall of my garage (south-facing) for about 10-12
years, and has never flowered, though it produces plenty of leaves.

Any suggestions?


I first posted this here 10 years ago, some found it useful then:

Wisteria in its native habitat is a forest plant. Mainly it grows in forest
with a high canopy and little light down below. Its method of
growth/flowering is to climb to the top of the tree canopy and flower there
in the light. How does the plant know that it has reached the top? Simple it
reaches the top of the canopy and flops over. In flopping over the flow of
hormone from the apical bud (the one at the growing tip) is disrupted and
buds below change from growth buds to flower buds.(Look up apical dominance
in a horticultural text book for a more rigorous description)


In pruning a Wisteria we are trying to fool the plant into thinking it is in
its native habitat and has reached the top of the tree canopy. Tall order?
(;-) No! quite simple really! We disrupt the flow of hormone from the apical
bud by cutting it off!!! This simple action instructs the buds below to
switch from growth to flowering mode.


How and when to prune?


Council of perfection: Never let extension growth get beyond two buds! When
it
does cut it back! Yep! An impossible ideal.


Achievable compromise: In the main period of growth ??July/August?? first
remove all weak, tangly growth completely to leave a number of main stems
(how many depends on how old the vine is and how large an area you wish to
cover). Then remove all extension growth to six buds from the main stem.
This
action promotes the growth/flower switch. Then in the dormant period
??Jan/Feb?? cut back these six bud stubs plus any further extension growth
to
two buds from the main stem. Hey presto you have created a flowering spur.
Enjoy the show in the spring & restart the pruning process in the summer.


(Why 6 buds first? Dunno. Maybe to avoid die back?)


How old before it flowers? Difficult to say. How old when you bought? this
years graft stock or a larger nursery grown plant? And: If you want it to
grow tall to cover an area you cannot do the essential pruning hence each
years growth if extension growth only: No flowers till it reaches the end of
the area or you prune. If you prune for flower it takes for ever to cover
the area. But, and this is an essential but, make sure you buy a grafted
plant as these come from early flowering parent strains. A seedling plant
may
be a complete reversion to its forest form.....


I have followed this pruning regime on innumerable Wisteria plants some
newish some old and threatened with removal 'cos "it never flowers". I have
yet to find one which fails to respond. But, do I hear someone ask, have I
ever found one which flowered without the labour intensive pruning? Yes!!
But
in each case it was on a pergola and was grown as a "roofing" plant and if
you think about it, this situation mimics closely the plant's habitat, it
gets to the top of the pergola and flops over and flowers!! But if you want
to clothe the legs of the pergola in flower then the pruning regime must be
followed.


Sorry I seem to have waffled on for rather a long time but I hope it is
useful!




pk