Safe, healthy and beautiful pruning requires just the right combination of scientific knowledge, artistic skill, and, of course, the proper tools for the job. Armed with a basic understanding of plant growth and response systems, every gardener should be able to keep their gardens properly pruned, vigorous and picturesque.

Some basic plant science: Before you start cutting, it is critical to realize that plants do not have immune systems like people have. They don’t have the ability to send disease- and injury-fighting defenses out to heal cuts or battle back disease the way that we do. Instead, they respond by walling off their healthy areas from damaged or diseased sections. Plants are best able to create these protective “walls” at the point where a branch has emerged from another branch. At this junction, you may see a ridge or swollen “collar” on the stem. These raised areas should be left undamaged and intact on the healthy, living section after you cut. But, make your cuts as close as possible to this connection point and cut cleanly. Ripping and tearing is a big no-no.

Plant growth is regulated by a series of hormones. The bud at the tip of each branch (called an apical bud), whether at the tippy-top of a large conifer or the end of a side branch on a tiny maple, excretes a hormone that travels down the stem, controlling whether the buds along the stem remain dormant or open up to create new branches. This is why when we shear a shrub it appears to flush out with new growth. Each shearing cut removes hundreds of tiny apical buds as well as the regulating hormones they exude. This is why when a tree is topped (also a big no-no), several ugly shoots are likely to emerge – often from immature buds that may form weak, hazard-forming branch attachments.

So, rather than cut off the outsides and tops of your trees and shrubs, instead clear out the interiors of dead, damaged, rubbing or suckering branches first. Lastly, make any shaping cuts, but be sure that these cuts are made where a branch connects to another one. The result: this trimming method will remove the apical bud and all of the buds it was controlling on the branch below it, or your cut will leave behind an existing stem with a bud leader, which will take over apical dominance.

Artistic skill: If you follow the basic guidelines described above, odds are your pruning cuts will look beautiful. Art follows science in this case. Really, the sign of a good pruning job is that you can barely tell that cuts have been made. The finished plant will look open and airy and will have a natural looking form. (Unless, of course, you’re creating a  topiary garden filled with lots of sheared shapes.)

Picking the right tool for the fine-pruning job:

Whenever I go into the garden to work, I’m sure to be wearing two holsters with pruning tools – a bypass hand shear and a folding hand saw. The hand shears are perfect for most cuts, but when I encounter a branch too large for shears to cut cleanly, I pull out the saw.

When using a saw, I’m careful to make an undercut followed by a cut that removes the weight of the branch. I do this about one to two feet away from the point where this big branch meets another one. Doing this helps ensure that I remove the weight of the branch without accidentally tearing the part of the tree that I plan to leave intact. After I have removed the weight, I then make an undercut followed by a complete cut to remove any stumpy branches.

On some occasions, I’ll need a taller tool for cuts higher than my arms and ladder can reach. For these situations, I gather up a pole saw (aka Tree Pruner) and carefully clip and saw to clean out tree interiors.

Remember: Keep those pruning tools sharp for clean cuts and to make pruning easier on your body. Keep your shears and saws clean and sterilized to avoid passing any disease from one plant to another or from one side of a shrub to the other side.

Timing: Picking the right time of year to prune can be tricky. Generally speaking, avoid pruning in fall just before cold weather settles in. Once trees and shrubs are fully dormant for winter, most can be pruned – depending on when they flower and the temperature. And, in many cases, doing some pruning immediately after a tree or shrub flowers works well – unless your plant is a food producer. Timing pruning can be tricky and vary by region as well as plant variety. Fortunately, Fiskars has put together a series of articles focused on how to prune particular plants properly.