6 Pruning Mistakes That Can Ruin Your Garden, According to Horticulturists

Pruning is an integral part of growing healthy plants. However, pruning mistakes can be very detrimental, introducing shock or infection to an otherwise thriving shrub, tree, or flower.

If done correctly, pruning can remove dead and diseased portions of a plant, preventing infection and keeping it in ideal shape. This practice can also improve a plant's exposure to sunlight and help increase air circulation, improving overall health.

So how can you avoid common pruning mistakes? We spoke to experts about the biggest issues that will compromise a plant's ability to produce fruit or vegetation. Here's everything you need to know to keep your plants looking and feeling their very best.

Pruning During the Wrong Season

The biggest pruning mistake to avoid is not doing so at the right time. For many woody shrubs, late winter into early spring is a great time to prune, says Anna Ohler, owner of Bright Lane Gardens—unless that shrub blooms in the spring.

“Spring-blooming shrubs and trees should be pruned after they flower,” she says. “If you prune them in late winter or early spring, you're likely to prune off freshly-formed buds, which will greatly reduce your blooms.”

The best time to prune depends on the specific plant. “Some prefer to be pruned while dormant, others during their growing season, and others during either the start or end of the growing season,” says Steve Corcoran, CEO of Lawn Love. “The key is to research your individual plants to learn exactly what they need.”

Pruning During the Wrong Time of Day

Timing is the most critical consideration when it comes to pruning. “This applies to not only the time of year,” says Luke Hammond, expert gardener at Seedtime. “Choose the best time of day to prune when possible. If you're pruning in extreme temperatures, this will add undue stress to the plant or tree.”

Trimming Without a Plan

Pruning should increase the amount of sunlight that reaches the interior of your plant or tree; it should also improve air circulation. In order to achieve these goals, it’s important to have a plan before haphazardly cutting away.

Assess your plant first, noticing any crossing or competing branches. Research your specific plant to find its proper shape and pruning guidelines. Finally, decide which cuts to make, and make sure you’re not removing more than one-third of its entire structure.

Using Dirty Tools

Any time you cut a plant, you create an open wound that's vulnerable to disease.

“When you prune with dirty shears or trimmers, you're exposing that open wound to bacteria or fungal spores that may be present on your tools,” says Ohler. “A quick wipe down with an alcohol wipe will ensure your tools are clean and ready to prune.”

Hammond advises using high-quality, sharp tools and making a clean cut in the right location with the proper angle. Sanitizing your tools periodically between cuts—even if it's for the same plant—can help decrease the risk of spreading diseases.

Dressing the Wound

Avoid putting anything on the cuts you make while pruning, as they will heal on their own. In fact, dressing the wound will only delay the plant’s ability to heal itself—and may introduce harmful bacteria or prevent the cut from closing. Do not, under any circumstances, paint the wound for cosmetic reasons or use a foreign substance—even if the packaging says it’s safe.

Taking Too Much

Over-pruning occurs when you remove too much from a tree or shrub in a single pruning session—usually more than one-third of the plant.

“This can shock the plant, which reduces its ability to grow, and leaves it susceptible to diseases and fungus,” Ohler says. “If you're trying to really shape an unruly shrub, plan to prune it in stages over the course of a few years, rather than pruning it all at once.”