6 Tips for Pre-Winter Perennial Pruning - Backyard Boss
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6 Tips for Pre-Winter Perennial Pruning

As winter quickly approaches, deciding which perennials to prune can be tricky. Even as an avid gardener, you may not be sure when you should prune your plants. Fall, winter, spring, summer, or not at all? As it turns out, it could be all of the above!

Many perennials require little maintenance in the fall, but others benefit from light or heavy pruning. Knowing which plants need pre-winter pruning is essential so you can help your garden thrive in the spring.

Here are six tips for pre-winter perennial pruning.

1. Avoid Pruning These Perennials

purple lilac tree in bloom
Image credit: webentwicklerin via Pixabay

The optimal time for pruning will vary depending on the type of perennial plants in your garden. Many plants prefer minimal pruning, especially in the fall, and are best left over winter. Know which plants you have to save yourself some time, and ensure you provide the best possible care for your perennials.

Prune spring flowering shrubs or those that flower on old wood, such as lilacs and oakleaf hydrangeas, after they finish flowering (usually late spring or summer). Prune evergreen shrubs, evergreens, summer flowering shrubs, and shade trees in late winter or early spring. If you are unsure, check your particular variety before pruning.

2. Prune Herbaceous Perennials

green leaf hosta in a shaded garden
Image credit: MabelAmber via Pixabay

Herbaceous perennials — plants that die back to the root system but come back every year — are more susceptible to disease and infestations. That’s because when the tops of the plants die, they are a perfect breeding ground for insects and disease. Common problematic herbaceous perennials include hostas, phlox, and bee balm.

Chrysanthemums, however, despite falling into this category, may be best left over winter without pruning. As a general rule of thumb, if you notice one of these perennials infested with insects or diseased, it’s best to cut it back to the ground in late fall. 

3. Prune After Several Hard Frosts

yellow flowers with frost in the garden
Image credit: Lakeblog via Pixabay

If you decide to cut back your herbaceous perennials, wait until after several heavy frosts. Many perennials can withstand a frost and continue to give the garden a pop of color through the cooler fall months. Enjoy the stunning fall garden while you can.

A heavy frost occurs when the temperatures drop below 28 degrees Fahrenheit. After a few heavy frosts, the upper portion of the plant will start to die. At this point, you’ll notice your plants are yellowing and turning mushy, signaling that it’s time to prune.

4. Check the Forecast and Prune Accordingly

tree branches against blue sky with sun shining through
Image credit: Marta Wave via Pexels

Check the forecast and plan your gardening days accordingly. There aren’t many nice days left before winter, so take advantage of them when you can. Even though the rain may be good for the ground, it’s important to prune on a mild, dry day.

Doing so helps prevent the spread of disease, and there’s nothing better than enjoying a warm fall day in the garden.

5. Prune Dead, Diseased, or Broken Branches

pruning shears rose bush
Image credit: Ray_Shrewsberry via Pixabay

Besides cutting back herbaceous perennials, fall is also a great time to maintain your other perennials. Completing some of this gardening in the autumn months can save you time in the cold winter and early spring.

Any time you notice dying, dead, diseased, or broken branches, you should remove them from your plants as soon as possible. They are susceptible to disease and infestation, and diseased branches can spread to neighboring plants. Removing this excess debris can also increase air circulation and help more light reach the plant.

Be sure to burn or dispose of any infected leaves or branches, as adding them to your compost pile may spread disease to other crops.

6. Remove Infested Plants

Snail on green leaf
Image credit: Krzysztof Niewolny via Unsplash

Leaving perennials over winter is fantastic for wildlife like birds and insects. It can also help insulate the plants from the cold. However, it’s best to remove the affected branches if you have insectslug, or snail-infested perennials. This helps ensure healthy plants in the spring months.

Cut insect-infested herbaceous perennials back to the base of the plant to discourage further spread, rather than just removing the infested leaves. Do not add these leaves or branches to compost piles.

Prepare to Prune

As the outdoor gardening season winds down, there may be time to prepare for the following year. Herbaceous perennials are most likely to benefit from pre-winter pruning, whereas it’s best to prune many other perennials in late winter, early spring, or summer. If you live in an area with heavy rain in the fall, you might experience more issues with pests and disease, requiring more stringent fall pruning practices.

Are you planning on doing any pre-winter perennial pruning? If you found this article helpful, please share!

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