Pruning garden plants
How to prune garden plants, Pruning garden plants, how to prune, gardener Bourne End, Marlow

Many gardeners or would be gardeners are intimidated by the prospect of pruning garden plants. It is perhaps the most mis-understood garden maintenance practice. But if you know what the objective is behind it, it becomes much simpler.

Consider first why you are pruning the plant. Then when is best for the plant, distinct from when is best for you. Sometimes the only time to prune is when you have time to do it.

There are several reasons for pruning

• Restricting the size of a plant, to avoid overpowering adjacent plants and the landscape.
• Removing growth that distracts from the shape, balance or symmetry of the plant.
• To remove diseased, dead, or diseased plant tissue, the Three Ds.
• Stimulate flowering and/or fruit production of old plants.
• Create a desired plant form, like a simple hedge or a more complex espalier.
• Direct growth in a particular form to eliminate or prevent problems. For example, reducing high of roses to prevent winter wind rock.
• Remove plant parts that obstruct views or visiblity, access, or conflict with structures or utility lines.

Different plants need different pruning

How to prune depends on the plant type. The RHS narrows it down to 13 distinct groups, but you can take a broader and simpler view. Consider first just three categories: broadleaf evergreen, narrowleaf evergreen and deciduous plants. Each type responds differently to pruning, so know the plant type before you begin.

Broadleaf evergreen plants

These have broad, wide, or flat leaves. Shedding of old leaves and the growth of new ones synchronise so that the plant looks like it is never without leaves.  Hence the term “evergreen”. Broadleaf evergreen plants include some of the most popular landscape plants. Examples include hollies, ligustrum (privet), photinia (most often Red Robin), elaeagnus, euonymus, azaleas, pyracantha, nandina (chinese or sacred bamboo), gardenia, pittosporum, osmanthus, buxus, camellia, aucuba, mahonia, fatsia, and magnolia.

Smaller leaved plants like Berberis also come into this category.

Broadleaf evergreens have latent buds along the branches and stems that can become a growing bud. A latent bud remains dormant until stimulated into growth. The presence of these special cells allows fairly drastic pruning of these plants without fear of killing them.

There are also dwarf forms with a compact, dense growth habit. These may need little or no pruning to control size or shape. Tip pruning may be used to encourage a thick, well-shaped plant, but can need rejuvenating after a few years. They can be pruned severely (6 to 12 inches from the ground) with satisfactory results. Do this in early spring, before any new growth begins.

But others are  substantial vigorous growers in need of annual or twice yearly pruning to control them. Tip pruning or trimming each year controls size or shape and is good practice for fast-growing broadleaf evergreen plants.

Narrowleaf evergreen plants, or Conifers

Conifers are mostly shrubs and trees that will not tolerate severe pruning. The narrowleaf evergreens have tiny, scale-like or needle-like leaves. Many produce a fruit-like cone, which gave the name “conifers”.

Examples include junipers, arborvitae, pine, cedar, spruce and teh controversial Leylandii. These evergreen shrubs need occasional foliage shearing in early spring to control size. they are without the latent buds that broadleafs have, meaning that you cannot prune them as severely. In fact if you cut back beyond the last green shoot you can end up with vast brown areas scarring the plant.

Conifers have a “dead zone”, located on the older portions of the branches of the plant. To avoid the “dead zone”, never remove more than one-third of the foliage. If you remove all the scales or needles with a pruning cut, no new growth will occur on the remaining limb, and drastic pruning of narrow-leaved evergreen plants can kill them.

This is why regular attention is essential. When they get too tall or wide little can be done to reduce them, other than complete removal.

Prune your conifers by removing a portion of the new lush growth, sometimes called the”candle”.  Once this growth has matured the buds present on it may not develop and grow. Trimming the tips of new growth, as you do with a hedge trimmer, before it matures can stimulate buds into growth. The effect is to  make the face of the hedge fuller and smoother.

Deciduous plants

Deciduous trees and shrubs have leaves like broadleaf evergreens but shed their leaves in the autumn or winter. They can be pruned hard without fear of killing them, like the broadleaf evergreens. Some common deciduous shrubs include forsythia, spiraea, weigela, lilac, rose, quince, honeysuckle, and hydrangea.

They’ll may need pruning to control the size and shape of the plant. Light to moderate tip pruning encourages thick new growth, resulting in bushy plants. Deciduous plants also may be pruned harder (thinning) or severely (rejuvenation), methods normally used before new growth begins in the spring.

Some different pruning methods

Pruning the tips encourages a thick, well-shaped plant.  That is effectively what happens with regular trimming.

Light tip pruning removes only a few inches of stem tips. This method is used to encourage bushier growth as it starts in the spring.

Thinning encourages broadleaf plants to flower and put on strong growth. This method is performed before the new growth begins.  Older or weaker branches should be cut back to a lateral branch or completely to the ground.

Shearing – hedge trimming – controls the shape and size of all types of shrubs. Shearing calls for clipping the newest foliage, usually just the surface couple of inches of new growth. Actually, shearing is a type of tip pruning that removes minimal foliage. Broadleaf evergreen hedges and screens are often sheared to promote thick, dense foliage.

The largest leaves of some hedging plants are not easy to trim and maintain a tidy finish. the larger the leaf the further away it should be from scrutiny. For hedges that are more closely observed try to use smaller leaved plants.

Rejuvenation is severe pruning used only on broadleaf evergreens and deciduous plants to control overgrown, leggy, and straggly plants. Use this method of pruning garden plants in early spring before the beginning of new growth.  For example, use it for fast growing clump-forming shrubs such as Buddleia and Mahonia. Cut back hard one-third of the oldest limbs  each year.

Espalier is the art of training the plant against a wall. Tall walls are best for this method. Pruning may be necessary several times throughout the year to direct the desired shape and form.

Topiary is the art of shaping plants into ornamental forms by careful pruning or trimming. Pruning is required several times during the year to keep them in perfect definition.

Timing

The time of year for pruning garden plants is important. Pruning at the wrong time will stimulate new growth, possibly left exposed to early frosts or freezes. It could also remove flower buds that have formed, reducing next year’s flowers. The following guidelines will help you prune your plants at the proper time. Most pruning is for size control, and should be done in late winter through early spring.

Pruning garden plants should take place after the landscape feature of your plant has passed. For spring flowering plants, prune in late spring as the flowering season is ending; this allows for adequate growth during the summer to produce flower buds for the next year. For fall-flowering plants, such as some of the camellias, use tip pruning or thinning method. Prune as the flowering season is ending. Plants with berries should be left until birds have eaten them.

For plants that produce flowers on one-year-old wood (usually those that bloom after June), such as hydrangeas, glossy abelia, and crape myrtle, cut away only those branches with spent flowers or prune (thinning method) in late winter to promote vigorous spring growth.