Grapevine Pruning and Training
Grapevines
are trained to a trellis or other support. An older trellis training system is the 4-cane-Kniffen
and is often used for American cultivars. The
bilateral cordon
training system is the most common system used in Missouri for both French hybrid and
American cultivars in commercial vineyards. Grapes may also be
trained to arbors or pergolas.
Three years are required to train vines to any system. In the first
season one to two shoots are trained to the top wire as future trunks.
You can form the trunk with one shoot and remove the other in the dormant
season, or you can train up a "double trunk" vine.
In the second season, shoots are trained along the top and bottom wires in
both directions for 4-cane-Kniffen, just along the
top wires for the bilateral cordon system or along the architecture of an
arbor or pergola where shoots, leaves and fruit is desired.
In the third season, fruiting
shoots will grow from the wood trained along the wires or other
architecture. Renew long
canes from the central trunk each year for 4-cane-Kniffen. Maintain mature cordons along the top wire
or structure and renew short canes (spurs) from the
cordon. Prune every
year in the dormant season (February - March). Pruning wounds may
bleed, but this is no cause for alarm.
Green shoots that grew from buds
on canes or spurs in the
spring will turn woody and brown in fall when they turn from shoots to
canes (photo above
shows the brown cane at the point it grows from older gray
wood). The buds
on the canes will develop into green shoots that bear leaves, tendrils and grape clusters
in the next growing season (see photo right).
When the vines are mature, they will fill up the allotted
space. Most of last years shoots that turned into the brown canes with
dormant buds being pruned in the dormant season will be removed. Vines
should generally be pruned back to 30 or 50 buds, depending on vigor.
The buds should be spread out as evenly as possible in the allotted
space (from 4 - 6 shoots per foot of trellis). Weak vines should be pruned back to about 20 fruiting buds
and later de-fruited so that they can become stronger.
Some canes or spurs that are not used to produce the crop but are
healthy may be cut back to 1 to 2 bud "renewal spurs". These renewal
spurs will produce green shoots that change into canes for the next years
crop. The trunk (and top cordon in bilateral cordon training) is maintained year after year and the new canes are
selected from this wood every year. It is important to keep the
renewal spurs and the fruiting wood close to the trunk or cordons in order
to maintain the architecture of the training system.
