The ABC’s of Pruning: When and How to Prune to Get the Best Results

pruning shrubs and trees

Learn how to prune your shrubs and trees

Pruning seems like a no brainer until you have your shears in hand and are standing in front of your shrub or tree and you aren’t so sure where to start and more importantly, where to end! Here we offer some simple tips for best-pruning practices to help guide you as you stand in front of your beloved plant or to give you some background information when you decide to hire the experts.

“It’s key that you don’t treat your entire property in one way when it comes to pruning. It’s important to know what you have so you know what to do and when. Many of our clients ask us to prune during their fall clean up, which isn’t ideal, because in the fall you can only work on a few of the plants in your landscape. Since so many of the plants are off limits, it’s best to wait until the dormant or green season to prune,” says Mike Annes, Greenwise Client Relationship Manager.

Why Do I Need to Prune?

Pruning serves so many purposes, from encouraging flowering and fruiting to getting rid of diseased or damaged branches to promoting growth. The key is removing certain kinds of growth before problems start.

For example, when you properly prune younger trees, you help the tree develop a robust structure and grow in an eye-catching way. If you start when the tree is young, you are less likely to end up with an overgrown tree that will require a lot of corrective fixes later.

Pruning is a good way to cut back fast-growing shoots, suckers or water sprouts, which don’t look good and are weak, so more likely to break as they grow.

What are shoots, suckers and water sprouts, you ask? Good question. Shoots and sprouts are terms used interchangeably and refer to those new branches that sprout from older branches in the tree or shrub. They often sprout or shoot up perpendicular to the larger branch. You don’t want to get rid of these entirely, only prune about half of them.

water sprouts or shoots

You can see the water sprouts or shoots growing straight up from the main branch

Suckers come up from the ground and compete with the existing tree, so you want to get rid of all of them so they won’t weaken the tree. Suckers in bushes, such as Lilacs and Viburnums, will help rejuvenate the plant, so you don’t need to get rid of those; maybe just thin them out, depending on how many there are.

suckers at the base of a bush

Suckers form at the base of a shrub or tree

Obviously pruning diseased, broken or crossed branches is necessary to prevent large branches from breaking off and causing injury or property damage. Crossed branches can rub against each other, creating wounds that invite infection and boring insects, which can affect the entire tree.

Don’t overdo it! We recommend that you don’t remove more than ¼ of a plant each season unless you are pruning to rejuvenate your plant and then it’s okay to prune down to 12 or 18”. By over-pruning you can create even more stress, which can lead to even more suckers and water sprouts as your tree tries to rebound.

Thinning branches help your plants breathe. When air circulates properly through a plant, it helps your plant remain disease free and reduce insect damage. When thinning, you want to thin out those branches that make up the dense mass of the plant. Be careful! Take a step back after every few cuts to make sure you are creating the shape you want. You don’t want to hollow out the center, so be careful not to prune too much.

When Should I Prune?

When to prune depends on what you are pruning. Around here, from November to mid-March, our plants are in a dormant stage. Did you know pruning cuts heal faster during dormancy? That makes winter the best time to prune, shape and thin many of your deciduous plants, trees and shrubs. Even making large cuts is a low risk venture this time of year. Plus, you get fantastic results in the spring!

Winter is also the only time you should prune Oaks and Elms. Oaks are protected trees in our area and should only be pruned in the winter so that you don’t transmit diseases.

Evergreens and Maples should be pruned in the spring, summer or early fall. Pruning evergreens too late can promote young growth that isn’t strong enough to handle the cold weather, making it burn off and turn brown. And Maples bleed, so you shouldn’t prune them after November. By bleeding we mean you’ll see sap dripping from the cut you’ve made. This won’t impact a mature tree, but it may cause problems for a sapling to lose so much sap. It’s best to avoid any problems by pruning your Maples in the summer. Once the leaf buds open, the sap is no longer under pressure and won’t leak out during pruning.

Your flowering shrubs should be pruned as soon as the flowers fade in May or June. If you prune them after July, you might affect how much they flower the next season.

Here’s a quick guide for pruning depending on if you are doing aesthetic or structural pruning.

Aesthetic Pruning

Aesthetic or in-season pruning is when you want to reduce the height and width as well as the overall shape of your shrub or tree. Here’s the rule of thumb:

  • Prune in season from May through July
  • Prune flowering shrubs, such as Lilacs or Viburnum, soon after the flowers fade between May and June
  • Prune hedges between May and July, and if you’ve got a formal hedge, you should do this twice during the season

Structural Pruning

Structural pruning is when you want to thin and rejuvenate your shrubs and trees. For shrubs, we typically only cut back ¼ of the plant per season. This is best done during the dormant season, typically after January 1. When you want to prune to rejuvenate a plant, that’s best done in the late dormant season from late February to early March.

Some Major No No’s When It Comes to Pruning

Snipping the tips:  when you snip a little at the tips, you can do more damage than making large cuts. Pruning stimulates growth, so when you snip a little at the tips, you are creating an environment where several new branches can take its place. Pretty soon, you’ll have a plant with way too many branches.

Shearing the top:  This is called “topping” and you don’t want to do it unless you are purposely doing a pruning technique like pollarding. When you shear off the top, you’ll create a new arrangement of shoots that could make the shrub unmanageable. Instead, you want to follow the natural lines of the plant when you prune.

Leaving a stub: When you prune, you want to prune back to a bud or branch rather than leaving a stub. Stubs encourage horizontal sucker growth and disease. Be sure to prune above a bud, so you can get a new branch to grow from the bud.

Skipping the winter pruning: dormant pruning means healthier plants when spring arrives. And it will arrive! So, don’t skip pruning those plants that thrive with dormant pruning in the winter. If you do snip the tips or shear the top, be sure to team that up with winter pruning.

What about Evergreens?

Most evergreens have a strong central branch leader, which requires little pruning except to control plant height, increase the density of branching, or to shear into special shapes. When evergreens do need pruning, they typically need to be pruned at different times of the year.

Arborvitae will withstand heavy pruning and shearing because new branches develop from concealed buds in the corners of the branches. It’s best to prune these in early spring or mid-summer.

Yews: To maintain size, prune in the late winter or early spring, before new growth begins. Prune them again in mid-June. If you shear your yews, do it after new growth has expanded. Follow-up shearing should continue throughout the growing season. To avoid stimulating new growth late in the season (thus preventing winter injury), do not shear yews after August.

What’s the Difference between Pruning and Shearing?

People often ask for shearing when they mean pruning and pruning when they mean shearing. What’s the what? Shearing is what we often do to shape a yew or a formal hedge. You can shear using a machine or by hand and it’s very noticeable.

Pruning, on the other hand, when done correctly should be less obvious and is always done by hand.

“With pruning you don’t want to make it noticeable. You are simply cleaning out dead and crossing branches or any branches rubbing up against the house or hanging too low over the walkway. When you do it right, it’s hard to know you’ve done it. When it’s obvious, you probably have over pruned,” explains Marcos Ayala, Greenwise Client Relationship Manager.

Need help with pruning? Greenwise is happy to help. You can contact your client relationship manager at 847-866-1930 for more detailed pruning plans for your property.

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