PRUNING ROSES WITH HEDGETRIMMERS:
British Trials Show It Produces More Blooms
By RNRS President, Ken Grapes
When next you are at our Gardens at St. Albans, do leave time to see the
various cultural trials which are now in progress, while bearing in mind
that some of them will take a few years to provide concrete evidence of
their efficacy or otherwise.
Many people, both within and outside the Society, are aware of the pruning
trials being carried out in association with the Consumer's Association, and
involving, in the case of one group of plants, pruning with a hedgetrimmer.
The results to date (and we are now into the third year) are, to say the
lease, surprising. But these trials are as yet by no means conclusive. Quite
apart from their intrinsic value, trials make us reassess accepted practice
and can be very thought-provoking. Appraise them yourselves.
Garden Trials Began In 1990
In spring, 1990, the Consumer's Association set up a trial in conjunction
with the Royal National Rose Society at St. Albans, to investigate whether
the time-consuming traditional method of pruning roses is really necessary.
Our trial was carried out on established beds of four varieties of
large-flowered (Hybrid Tea) roses and four cluster-flowered (Floribunda)
We pruned one third by the Traditional method, being careful to observe all
the rules, such as cutting to outward-facing buds and thinning out
Another third was rough pruned, by cutting all the shoots straight across
with pruning shears at the same height.
The rest were pruned with a hedgetrimmer.
The initial results aroused a lot of interest. Rough pruning and
hedgetrimmer pruning both induced stronger growth and an equally good or, in
many cases, better flowering performance than traditional pruning.
However, after just one growing season we could not say whether these easier
pruning methods would be free of longer-term problems. So we decided to keep
the trial going. Last year, we repeated the treatments and our rose experts
assessed the bushes in September.
The differences between the treatments were not quite so marked, but,
overall, the results were consistent with those of the previous year.
Rough Pruning and Hedgetrimmer Pruning again induced more growth and better
quality growth than traditional pruning.
With the Floribunda Roses, the blooms were again bigger and more numerous
after Hedgetrimmer and Rough Pruning. With the Hybrid Tea Roses, all three
pruning methods gave good blooms.
Traditional Pruning Method
All stems were pruned just above outward-facing buds with the cut sloping
down away from the bud. Dead or damaged shoots were cut back to healthy
wood, and the centers of the bushes were thinned out, if overcrowded. Old or
weak stems were cut back to a quarter of their length, or removed
Stems of the large-flowered (Hybrid Tea) roses were cut back to at least
half their length. The cluster-flowered (Floribunda) roses had some old
stems cut back to within a few inches of the ground, whilst new shoots
growing from the base were only lightly pruned.
Rough Pruning Method
The shoots were all trimmed with pruning shears at the same level, and all
the cuts were roughly horizontal. We did not worry about whether the cuts
were above a bed, or not. Each rose was trimmed to the same height as the
traditionally pruned block in that bed. Any dead wood was removed.
Hedgtrimmer Pruning Method
Roses were cut to the same height as above, using a hedgetrimmer. No dead
wood was removed. The hedgetrimmer cuts were very ragged, leaving lots of
snagged and ripped shoots.
Dieback Not A Problem
Traditional pruning methods for roses were developed centuries ago, when
most varieties were susceptible to dieback. These pruning methods have been
passed on from generation to generation, without question, ever since.
However, rose breeding has come a long way, and many modern varieties don't
suffer badly from the effects of dieback, because they are so much more
Dieback can affect new growth beneath the visibly damaged stems, causing
thin, weak shoots. These shoots produce fewer flowers, which are smaller,
and less well shaped than on normal plants. The weaker shoots are also more
susceptible to diseases such as blackspot and mildew, and they can bow over
and sag under the weight of flowers.
Our trials showed that Rough Pruning and Hedgetrimmer Pruning caused no more
dieback than traditional pruning.
The Trial Goes On
From our initial results, rough pruning, or using a hedgetrimmer seems to
give better short-term results than traditional pruning.
However, we do not advise that you switch pruning methods until we bring you
more long-term results. It is possible that roses which are roughly-pruned
may become overcrowded in the center, and therefore more prone to diseases.
Traditional pruning encourages the development of open-centered bushes. It
may therefore be necessary to alternate between Rough or Hedgtrimmer Pruning
and Traditional Pruning. We shall keep you updated on any new developments
as they occur.
Other Trials Underway
Although many Brit "purists" have foamed at the mouth, this particular trial
has achieved terrific press coverage and general interest. We feel that the
National Society should be doing this sort of thing on behalf of rose
growers and, indeed, this is but one of a series of trials now underway.
Tests are also in progress at St. Albans to compare ways of combating soil
sickness, to evaluate different planting practices and different mulching
materials (over 20 are being tried) and to assess disease resistance in a
spread of varieties.
Enthusiasts will keep this last-mentioned trial under particularly close
observation. The varieties in question are not sprayed but are otherwise
given normal cultural treatment.
This article was originally published by the Royal National Rose Society, in
conjunction with the British Gardening Magazine, "Gardening From Which?" It
was reprinted in the "American Rose" Magazine, August 1992.
We do not endorse the above pruning method. For the best way to prune roses
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