Pruning
your Clematis
“To
prune or not to prune?” is the most often asked question. It should be noted that incorrect pruning
would never bring an early death to the clematis. At worst an inappropriate pruning will only delay flowering. Furthermore, if all varieties were left
unpruned they would all flower very well.
However, as is explained below, the flowers would not necessarily cover
the plant as well as they otherwise could.
Our first
tip on pruning applies to all clematis varieties. The first February or March after planting all clematis should be
cut back. At this time, you should be
able to see leaf buds developing as your plant breaks dormancy. You should leave two sets of buds on each
stem between where you make your cut and soil level. In subsequent years the following recommendations should be used.
In
an effort to simplify things, we have used three main pruning categories.
Are
varieties that flower only on growth produced the previous year. Pruning should consist of cutting out weak
or dead stems as soon as they are finished blooming in May or June. Pruning later than June or very severe
pruning will result in fewer blooms the following spring. The very popular Montana varieties fall into
this group and even though they will survive in our colder climates, if the
tops are nipped off by extreme frosts, blooms that should have occurred in
early spring might occur in the fall, if at all.
Group (B) Group B
is broken down into two sub groups:
Group B
(1) – are the varieties that flower on wood that has been
hardened by the previous season’s growth.
Normal blooming patterns for this group consist of a heavy flush of
flowers in May-June on the previous season’s growth followed by a second
smaller flush of blooms in September on the current season’s growth.
Group
B (2) – are the varieties that bloom simultaneously on last year’s growth
and the current season’s growth. Group
B (2) varieties normally bloom from June to September continuously. For pruning purposes these varieties can be
treated either as group B (1) or group C and for that reason work extremely
well in combination planting with group B (1) or group C varieties. If planted alone a group C pruning regime
every second year is recommended.
For both
group B (1) and B (2), in late February or March a light pruning with some
variation in the length of the stems will help produce a well balanced group B
plant. Any weak or dead wood should be
removed at this time and careful spacing of the remaining stems is all that is
required. The spacing of the stems will
allow room for next spring’s mass of blooms to open pleasingly. A severe pruning will reduce the number of
blooms at the plant’s next flowering, but will not hurt the plant; in many
cases it will help produce a better-balanced plant. If your group B clematis has been neglected for many years, it
can be rejuvenated by severely cutting back most of the old growth.
Group C
These
varieties bloom only on the current year’s growth. Blooms commence in early summer and continue through to
fall. Plants should be cut back in late
February or March to two strong sets of buds on each stem as close to ground
level as possible. This will provide a
plant with blooms that start near ground level and continue to the top of the
plant. The majority of the Group C
clematis through a tree or have it bloom in an area above its normal blooming
height, this characteristic can be used to your advantage. You can prune an established plant at almost
any height or not prune at all to accomplish your objective. Keep in mind that Group C clematis bloom on
the current season’s growth, so that if treated in an untraditional way the
blooms will be at the tip of the plant and bare stem will gradually appear over
a few years. This provides an
opportunity to plant a lower growing group B variety to hide the bare stem and
to extend the blooming season.