It’s Pruning Season

The beginning of March marks the start of pruning season for New Hampshire gardeners and home orchardists. This time of year is also when UNH Extension typically offers in-person pruning demonstrations around the state. 

In March and into early April, tree fruits like apples and pears, and small fruits like blueberries and raspberries, remain fully dormant while the worst of winter weather conditions have passed. Most pruning is done at the end of dormant season because injury from low winter temperatures are avoided, and because flower buds are easily recognized and pruning wounds heal quickly. But pruning is often intimidating, especially without understanding the fundamentals, so learning why to prune is a good place to start.

For fruiting trees and berry plants, good pruning regulates growth, increases production and yields, improves fruit size and quality, prevents disease, and maintains plant health and vigor.

For ornamental trees and shrubs, pruning helps maintain plant vigor, creates and preserves good structure, increases flower and fruit production, improves health, enhances ornamental characteristics, and limits and manages size.

Simply following the “three Ds” of pruning will take you a long way. Prune out anything that is dead, damaged or diseased. To go one step further, prune out branches that cross over and rub the bark of one another.

Mastering pruning requires understanding how plants respond to different kinds of cuts. Heading cuts stimulate branching, and thinning cuts stimulate stronger growth of the existing shoot. By understanding how and why to make different kinds of cuts, and by understanding a particular plant’s natural growth habits, you can approach annual pruning with confidence and a plan. The resource below addresses pruning tools, types of cuts, how to make clean cuts, branch healing, and when to prune.

Basics of pruning trees and shrubs – UNH Extension fact sheet

Fruit Trees

There are commonly three different pruning situations you will encounter with growing fruit trees

1. Pruning and training young trees
2. Maintenance pruning
3. Renovation of neglected fruit trees

We divide fruit trees into the following groups:

• Apple and pear
• Nectarine and peach
• Apricot, cherry and plum

Fruit tree pruning usually starts the year after planting, such as with apples and pears that are pruned to a single leader, with staking as a key first step. Training nectarines and peaches in year one may be recommended in order to establish primary structural branches. Apricots, cherries and plums can be pruned into either a leader or open center system. Pruning aims to achieve balance by removing oversized branches and excessively low branches and should result in branches relatively uniform in size and roughly evenly distributed around the trunk.

The same principles continue to apply to mature, fruit-bearing trees. Annual pruning, along with proper fertilization, should keep the amount of pruning manageable. Branch angles become very important, with branches pointing down and branches pointing directly upwards typically getting removed through pruning. The angle of branches you select to keep depends on the type of tree and the pruning system you’ve chosen.

Overgrown fruit trees should be pruned over the course of several years, removing no more than 1/3 of a tree’s canopy in a single year. Removing large upright shoots in the canopy and shortening excessively long limbs with thinning cuts, along with removing dead, diseased and damaged branches and crossing branches, are good areas to focus your efforts.

Resources

Growing plums, cherries and apricots in NH home orchards – UNH Extension fact sheet

Care of the mature backyard apple tree – UNH Extension fact sheet

Training and pruning young apple and pear trees – UNH Extension fact sheet

Pruning apples (video) – Umaine Cooperative Extension

Planting, training and pruning peaches (video series) – NC State Cooperative Extension

Small Fruits and Berries

Each of the small fruits grown in New Hampshire have different and unique pruning requirements and need to be discussed individually. Here we will focus on blueberries, brambles and grapes.

Highbush Blueberries

Blueberries should be pruned once a year in the late dormant period. Young blueberry plants don’t require or benefit from pruning beyond removing dead branches and weak, spindly growth. Once blueberries have been established for 3 years or more, pruning increases in order to remove older, less productive canes, thin out productive canes and removing weak fruiting branches on remaining canes.

Growing highbush blueberries – UNH Extension fact sheet

Pruning demonstration video – UMaine Cooperative Extension

Blackberries and Raspberries

Pruning brambles like blackberries and raspberries is unique, both in technique and timing. Depending on management and cultivars selected, you can influence whether you get one crop or two crops each year from red raspberries. Pruning brambles aims to prevent and manage disease by improving light penetration and air circulation, as well as contain the plants from outgrowing their planting space and improve production. Fall-bearing raspberries are typically mowed to the ground in the early spring, and raspberries and blackberries should both be tied to wire or posts for support, unless stout enough to support themselves well in a vertical position.

Growing raspberries and other bramble crops – UNH Extension fact sheet

Pruning demonstration video – UMaine Cooperative Extension

Grapes

Like most other fruits, grapes should be pruned in the late dormant season and should be pruned each year. During the planting year, grapes should be pruned back to two strong buds, and shoots should be allowed to grow and tied loosely to a stake. In the second year, grapes should be pruned back to 1 or 2 strong, upright stems, and your stem or stems should be tied to a training stake. Other pruning techniques beyond year one and two depend on the training and support system used, and there are four primary systems that can work well in New Hampshire home vineyards. All systems aim to keep vines productive and contained, and pruning plays a critical role in preventing and managing disease and are described in the fact sheet referenced below.

Pruning and training grapes in home vineyards – UNH Extension fact sheet

Ornamental Trees and Shrubs

Most ornamental trees and shrubs are pruned in the late dormant period, with the exception of spring blooming trees and shrubs which should be pruned immediately following bloom. If those trees and shrubs are pruned in the late dormant season, including notables like lilac, rhododendron and bigleaf hydrangea, you will remove the flower buds already developed and poised to bloom. Ornamental crabapples, pears and other members of the rose family are notable exceptions to this rule and should be pruned in the early spring to reduce the likelihood of disease (fire blight) transmission.  Like most fruits, late summer and fall pruning should be avoided due to potential for dieback at the site of pruning wounds.

Pruning deciduous trees: UNH Extension fact sheet

Learn more from a previously recorded virtual event

UNH Extension scheduled four interactive virtual sessions on pruning, offering opportunities for home gardeners and homesteaders to learn with Extension specialists. These sessions were hosted on Facebook Live. You can watch the recordings of those sessions through the links below.

• Pruning Tree Fruits with Jeremy DeLisle and George Hamilton
• Pruning Highbush Blueberries with Olivia Saunders and George Hamilton
• Pruning Brambles and Grapes with Becky Sideman, Heather Bryant and George Hamilton
• Pruning Ornamental Trees and Shrubs with Emma Erler

Listen to Pruning, Topping & Staking Trees & Shrubs, plus Witch Hazel Appreciation, an episode of the Granite State Gardening podcast.

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