OVERVIEW OF PRUNING:
Tips for Maintaining a Healthy Garden

Any attempt I make here to fully cover the topic of pruning will need more pages than this column allows. What I do plan to do is challenge each of you to go out and get a good book on pruning.

One of the primary reasons for pruning is to make sure that plants are as healthy as possible. Proper and timely pruning removes weak and damaged limbs, and reduces the risk of disease and infection. Pruning also increases a plant's ornamental value and improves its natural appearance.

You have to first understand the principal way a plant responds to pruning in order to realize its full potential.

Knowing how plants grow will aid you in the how-and-why of pruning. Pruning should never be done without a good reason or clear purpose.

Why Pruning Works

The most important thing to know about pruning is that when a part of a plant is removed, its hormones are diverted. Plants have growth-regulating hormones that ensure the tips will continue to grow away from the roots: “apical dominance." When you remove these young green shoots, the plant is forced to divert its growth hormone, auxin, to the next highest node.

A node is usually located in the space where the leaf connects to the stem. Most plants respond with new growth at the node closest to where the cut is made. Some plants respond by producing multiple stems along nodes below the cut.

Each plant has different requirements when pruning. Knowing the growing habits of the plant will help you properly prune. Pruning ensures vigorous new growth, and keeps dead and decaying limbs from spreading disease and infection to younger healthier limbs.

Controlling Plant Size

Heavy pruning can be used to control plant size. When pruning heavily, there is usually a flush of new growth that leaves the impression it is because of pruning. However, you have actually cut down the plant's ability to produce food (photosynthesis), while forcing the plant to use up its stored food. Repeated heavy pruning without proper fertilizer actually hurts the plant in the long term. And even in the best cases, you will alter the new growth, not increase it.

Formative Pruning

Selectively removing buds in young plants to produce a particular form or a desired shape is perhaps the most obvious reason for pruning. For garden plants, this will also produce a pleasing appearance.

When To Prune

When pruning, it is important to understand the habits of the plant. If you are thinking about pruning your hydrangea back to the ground this spring, be prepared for sparse, if any, blooms this year. You see, hydrangeas only bloom on last year's stems, and pruning them back to stubs in early spring will produce wonderful leaves and very few, if any, blooms.

Always be careful when pruning in early spring since this is the time that food reserves are moving rapidly back up the stems, and cutting back harshly in early spring can severely hurt the plant. This problem can be avoided by pruning in late winter or once the plant has fully leafed out.

Winter pruning of deciduous trees allows you to see the structure of the tree without the obstruction of its leaves. Winter pruning also helps prevent the entry of pathogens, since healing will be rapid in spring. 

How To Prune

Once you know the time is right for your plant and you know which parts to remove, take care to perform the job in a way that ensures rapid healing with minimal risk of infection. Make clean cuts with reliable tools suitable for the task at hand (see this month's product profile), and avoid crushing or fraying twigs. This is where referring to a good pruning book is particularly helpful.

Prune above a bud that is the right height for the desired outcome. Make sure that the uppermost bud is pointing in the preferred direction, and make an upwardly sloping cut, starting on the opposite side of the shoot to the bud. Cutting on an angle ensures rainwater runs off. Refrain from using pruning seals since their benefits have not been proven; in fact many professionals are doubtful if these products have any value.   

Tools

Depending on the type of pruning you are planning to do, there are many products on the market. Only purchase tools from a company that is well respected - discount pruning tools produce discount results. Keep your tools sharpened and clean, and your plants will respond in a healthy manner.

The Final Cut

As with any overview, this article has hopefully inspired you to do more research in this area of gardening. Keep in mind that proper pruning is a must for plant health. The right tools and knowledge of pruning techniques will take you far in this very important yet often discounted area of plant maintenance.