introduction to PruninG 87
individual perennial often can be pruned many different ways for similar results.
There are also different ways it can be pruned for slightly different results. Certain
tools or techniques may be preferred by some and not others. Use the information
provided here as a guideline, then experiment, have fun, and learn as you go.WHY WE PRUNE
What, how, and when to prune perennials varies from region to region, from year
to year, and with the age of the plant. The condition of the plant, whether it is
healthy or stressed, and the fertility of the soil will affect pruning requirements,
as will weather conditions in a given year. Watch your plants closely: they usually
will tell you by their appearance what kind of pruning is in order. If in doubt (and
if I haven’t given you the answer in the Encyclopedia of Perennials), just watch
the plant and experiment—leggy, tatty old growth and new fresh growth at the
base of a plant are red flags summoning the pruners. Pruning also depends on
the individual gardener’s objectives. I have listed below some important objec-
tives in pruning; they are discussed in detail in the chapters that follow.Extend bloom period or promote repeat bloom
Extending the bloom period or promoting repeat bloom is one of the most
important reasons to prune perennials. Even though we all appreciate the many
attributes of perennials, the beauty of their flowers is probably the primary
reason that most people grow them. Most perennials only flower for 3 weeks,
some for an even a shorter period of time, so if something can be done to extend
the flowering season, it will be a worthwhile endeavor. Deadheading, the
removal of faded or spent—basically dead—flowers, is a rather morbid name for
a technique that can give life to your garden through prolonged bloom or repeat
bloom of certain species. In many (but not all) cases, if the bloom is not allowed
to go to seed, the plant will continue to put out new blooms in an attempt to
complete the life cycle. When we deadhead, we force the plant to put its energy
into new flower and shoot production, rather than into seed production.Encourage lush new growth
Cutting plants back when old growth has become tatty can promote lush new
growth from the base of the plant. This new growth contributes to the overall
appearance of the garden, refreshing it and holding that spot in the overall
design. Remember, foliage form, texture, and color contribute to the garden
effect for a much longer period of time than do flowers.Regenerate or extend the life of plants
Pruning is not simply cosmetic. Pruning can also increase the vigor and life
expectancy of the plants, as well as improve their resistance to disease and harsh
weather conditions. This is particularly true with woody perennials—perennials
that have hard and thickened stems or trunks and do not die back to the ground.
For a wide range of short-lived, usually biennial species, life span can be
extended by several years if the plants are cut down immediately after flowering.
As discussed above, a plant’s main biological goal is to produce seed, which will
become the next generation. Unlimited seed production pulls strength from the
plant and leads to death of these biennials. If the deadheads are removed before
seeds start to set, the plants get confused, thus stimulating new shoot production
and a further year of flowering. This can be an advantage or a disadvantage,
depending on your objectives. I often prefer seeding some species for a more
natural, unplanned look. Pruning allows us these choices.