These 7 Plants Should Never Be Pruned in January – Wait Until Spring Instead

January is a classic pruning month. The holidays have passed and spring, while it might not be around the corner, is looming large in your mind. The garden is dormant, and your plants are all in need of a good trimming. Right?

Not so fast! One of the basics of pruning is timing. So while pruning plants in January is a vital part of garden revitalization, you can't go cutting willy-nilly. Some plants can be seriously hurt by January pruning. Winter burn is a serious threat, and chopping back some plants removes vital insulation that keeps them protected.

Disease is another factor. Certain fungal spores are happy to spread during those occasional January warm spells. And a dormant tree or shrub can't quickly heal over pruning cuts, which leaves open wounds in the bark for those spores to land on. No good!

It's not all about the plant's health, either. Many plants that bloom in spring (and some that bloom in summer) set their flower buds the previous year on old growth. Every branch you prune in January cuts away potential blossoms. It might not hurt the plant, but it will make this year's flower show a lot more lackluster.

Here's a list of seven plants you should never prune in January.

1. Forsythia

Forsythia (Forsythia spp.) is one of the very first bloomers of spring. In fact, these bushes are so ready to flower that they often jump the gun, opening up their blossoms well ahead of time during an unseasonably warm spell. (My own poor shrub decided to bloom right before Christmas this year!)

It should come as no surprise, then, that forsythias have their flower buds set well ahead of spring. In fact they set them in the summer of the previous growing season. So every cut you make in January is going to be lopping off future flowers!

Leave your forsythia alone for now, and be ready to prune it in the spring, immediately after it finishes flowering.

2. Lilacs

Though they bloom a little later, lilacs (Syringa vulgaris) are in much the same boat as forsythias. They develop next year's buds in the summer, soon after flowering. If you prune them back in January, you'll be stuck with a year of no flowers.

Prune lilacs in late spring or early summer, immediately after flowering but before new buds have set.

3. Rhododendron

Most rhododendrons (Rhododenron spp.) are evergreens, so you may see their foliage standing out against the snow and feel inspired to trim them back a bit. Resist the temptation! Yet another early spring bloomer, rhododendrons set their flower buds the summer before. If you prune them in winter, you're signing up for a very lackluster season.

(The same goes for azaleas, which are technically a kind of rhododendron.)

Prune your rhododendrons in spring, after all the flowers have faded.

Drop the Pruners, Pick These Up Instead

4. Bigleaf Hydrangea

Hydrangeas are famously tricky to prune, because there are so many different varieties that have different blooming patterns. Some bloom on old wood, some on new, and some on both. Bigleaf hydrangeas (Hydrangea macrophylla) are old wood bloomers. That means their buds develop in late summer or early fall and overwinter on the plant. Prune them any time in winter, and you're lopping off potential flowers.

The best time to prune bigleaf hydrangeas is summer, immediately after the blooms have faded.

5. Lavender

Of all the plants on this list, lavender is probably the most sensitive. It's a Mediterranean native, used to dry soil and warm sun. That means it's especially at risk during the cold, dark winter – the only chance it has of survival is entering a deep, undisturbed dormancy. And what's more disturbing than getting pruned?

Pruning lavender in January exposes the inner, protected parts of the plant to harsh cold and wind. Moisture in the woody stems is likely to freeze, splitting open the bark and letting in even more cold.

Wait until summer, when your lavender is done flowering. Then you can give it a hearty trim.

6. Boxwood

Boxwood (Buxus sempervirens) is another plant that's very prone to winter damage. Have you ever seen boxwoods with brown leaves, entire sections of the shrub turned crispy and sad? This can be caused by a number of issues, but one major culprit is winter burn. Much like with lavender, removing branches disrupts the plant's natural insulation, letting cold both into the shrub's center and under its bark.

Prune boxwood in early spring, just as new stems starts to emerge. This will encourage healthier, bushier growth.

7. Peaches

Peach trees (Prunus persica) should never be cut in January. In fact, most stone fruit trees, including plums, apricots, and cherries should be left alone!

This is largely because of the prevalence of Silver Leaf Disease – a fungal infection that spreads via airborne spores that are most active during the damp, cold months of mid-winter. When you make a cut in January, the tree is dormant and unable to produce the protective callus tissue needed to seal the wound.

Prune peach trees in very late winter or early spring, when no rain is predicted for several days. This should give the tree time to heal over any cuts before the damp spread of disease.

Is January Pruning Ever Okay?

There's always an exception to the rule, isn't there? In this case, there are actually three generally accepted exceptions. Those are the 3 D's – dead, damaged, and diseased. If parts of your plants fit into any of these categories, it may be okay to prune them out, even in the depths of winter.

But before you start cutting, ask yourself why you would normally avoid pruning this plant. If it's to preserve already-set flower buds (say on a rhododendron or an azalea), then cutting out dead branches isn't going to do as much harm. If it's a boxwood, say, then removing dead or damaged foliage is going to expose more of the shrub to the elements, and might actually lead to more damage. Just use your common sense.

I would add a fourth D to this list: dangerous. If a limb of your peach tree has broken off and is hanging above your yard, don't wait until spring! Call in a professional to get it removed right away.

Shop Winter Pruning Essentials

If you do need to prune, do it with the right gear.