To prune: the google dictionary defines this horticultural verb as “…trim (a tree, shrub, or bush) by cutting away dead or overgrown branches or stems, especially to increase fruitfulness and growth.”
For most people, pruning is a chore that must be done every year, the reasons for pruning differing from plant to plant. Like grass mowing (which is a form of pruning), landscape pruning is intended to produce a neat, organized landscape. So, every year in late June through July, many landscapes are unfortunately transformed from apparently uncontrolled growth to tidy balls, squares, pyramids and umbrellas, stiffly-disciplined groups of shrubs like soldiers on parade. Unless the plant material being pruned is an evergreen species (boxwood, yew, juniper to name a few) being formed into topiaries, or those few deciduous species that are suited to special pruning, hornbeam hedges, espaliered or fan-shaped fruit trees for example, these formal shapes may look out of place and prove detrimental to the plants. Deciduous plants are usually unsuitable for this type of formal pruning for many reasons, among them a fast growth rate which requires frequent pruning, and different growth habits that require different timing and placement of pruning cuts.
Boxwood Topiaries
Landscape plants are chosen for a variety of reasons, among them their flowers, fragrances, flower color, foliage color, bark color, ease of culture, hardiness, and growth habit (such as weeping, upright or spreading). Though some evergreens such as rhododendron, mountain laurel and gardenia are cultivated for their flowers, most evergreen species are cultivated for their shape, foliage color and size with little regard for their flowering habit. Deciduous species, on the other hand, are often grown for their flowers, which can occur on wood that is the current year’s growth, last year’s growth, or two-year-old growth, depending on the plant.
PRUNING DECIDUOUS PLANTS
Identifying the plant is key to pruning deciduous plants. You do need to identify what type of wood the plant flowers on, but you don’t have to be a botanist to do that. Observation may prove sufficient. When does the plant flower? Generally speaking, plants that flower on current growth flower later than those that flower on previous years’ growth. Does the wood appear light-colored when it flowers? Old wood is usually darker than newer growth. The internet or your local garden center can also prove a useful source of information about your plants. Some care must be taken, lest you inadvertently rob yourself of a display of flowers because you cut off all the flowering wood. Plants that flower on current growth should be pruned in early spring, usually March, to allow new growth to form before flowering. Plants that flower on one-year-old wood should be pruned after flowering, generally to shape the plant and clear away old, diseased, mal-formed wood. Plants that flower on two-year-old wood may be pruned at any time, generally to shape the plant and trim away wood older than two years old. Well-executed pruning will maintain a plant’s ability to flower, keep it healthy and within bounds in the landscape.
Well-pruned mature forsythia (specimen plant)
Pruning isn’t just about appearance. The health and productivity of plants is a major concern of pruning. Deciduous plants generally respond well to appropriate pruning, producing more flowers and/or fruit as a result. Reducing the overall size and thinning the interior of plants reduces the risk of disease, as it promotes free air movement through the plant. The removal of dead, diseased and dying wood cleans up the plant visually, while decreasing the threat of future disease and canker problems. Branches that grow through the plant from one side to the other should be removed to prevent tangled growth. Old wood that is not producing good, viable growth should also be removed.
Typical pruning for fruit production
As you work at pruning, where to make your cuts will become increasingly self-evident. One rule that must be followed regardless of species or type of plant is that no more than 25% of the total vegetation is to be removed. Removing more foliage will compromise the plant’s ability to photosynthesize, and is very detrimental to its overall health.
Next time, the blog will continue the discussion of pruning by considering the challenges of evergreen pruning, and a general overview of types of pruning.