Dealing with Winter’s Wrath

May 23rd, 2014

We’re far enough along in spring now that it’s finally become apparent what croaked from our brutal winter and what was merely set back.

I think that overall, most plants are going to recover, despite the worst winter in 25 years for plant damage. (For more on that, see the post I wrote on what caused all of the botanical destruction.)

Way more leaf browning and dropping happened this winter than usual, but I’m seeing a majority of denuded branches pushing out new leaves in the last couple of weeks.

In the case of hydrangeas, butterfly bush and crape myrtle, most of them survived, but the top growth generally died. That means you’ll have to cut off dead branches back to the new growth that (hopefully) is emerging from around the base of the plants.

It’s taken nearly 2 to 3 weeks longer than usual to determine what’s dead and what’s not because of the cool, slow start this season.

Normally, even the last of the spring waker-uppers is back to life by mid-May.

When the latest emergers finally poke out their new shoots or leaf buds, that’s a sign that everything else that’s alive should be showing new growth as well.

Just as forsythia is a good indicator shrub at the season’s beginning, crape myrtle and nandina are good indicators at the back end.

Black locust is one of the last trees to leaf out, and hardy hibiscus is one of the last perennials to show its face. If you’ve got a fig, that’s about as late to leaf out or poke up new shoots as anything.

When you see those plants back to life, you should be seeing life in other plants damaged by winter.

Of course, the indicator plants also could be dead. So even in a late year like this, if nothing is happening by mid-June, you can figure your lifeless plants are, as Garden Talk radio host Bob Carey terms it, “toast.”

Other death signs are that your leafless branches will snap instead of bend. And when you scratch off the bark, you’ll see brown, not green.

If all of those check out, it’s time to throw in the towel and think about a replacement – either now (if you keep the replacements well watered through summer) or at our next good planting window (right after Labor Day through October).

So what do we do now with our winter-ailing plants?

Here’s a case-by-case rundown:

Things That Suffered Foliage Damage Only. These are plants (primarily evergreens and especially broad-leaf ones) that suffered winter “windburn.”

Unable to take up new moisture from the frozen ground to replace that being lost through foliage, windburned plants first show browning around the leaf edges or needle tips. In more severe cases, the leaves completely brown and eventually drop.

Assuming the branches are still alive, new leaves and needles should now be poking out. You need to do nothing to these, other than possibly shaking off or pulling off the browned foliage to hurry along the replacement cleanup.

Plants to watch in this boat: azalea, rhododendron, holly, evergreen euonymus, ivy, cherry laurel, cotoneaster, boxwood, leucothoe, aucuba, daphne, hardy camellia, sweetbox, privet, blue atlas cedar, Japanese red cedar.

Things That Suffered Branch Dieback. This is one step worse than above. Not only have leaves or needles dropped, but the branches themselves have died.

This damage normally starts at the branch tips and works its way lower as the damage becomes more severe.

Sometimes it’s just the tips that die because that’s the newest growth, which is most vulnerable to cold winds, especially if the tips didn’t have sufficient time to “harden off” heading into winter.

Sometimes the branch death happens back to where snow insulated the wood and flower buds. That explains why you might’ve seen forsythia and quince, for example, flowering only low on the plant. And it explains why you now might be seeing leaf buds poking out low on some shrub branches while the higher or outermost sections are dead.

Anything that’s not showing signs of life by mid-June can be cut back to live growth or the whole way to the ground in the case of plants regrowing from the base or the roots. In other cases, you may need to thin out dead branches while leaving live ones to grow.

Plants likely in this boat: bigleaf or mophead hydrangea, butterfly bush, fig, crape myrtle, roses, nandina, Leyland cypress, scotch broom, genista (Dyer’s greenwood), redbud, photinia, mahonia and reportedly, even some forsythia. Everything in the above “Plants That Suffered Foliage Damage Only” category also could fit into this group if damage progressed from leaf damage into branch death. Cut back to live growth.

Note 1: Patience for regrowth is required here.

Note 2: Hydrangeas may not bloom this season because the flower buds on the dead branches are also dead.

Things That Are Dead: For plants where you’ve been waiting for something to happen but see nothing by mid-June, these are likely goners.

You can try watering, fertilizing and waiting a little longer if you want, but it’ll take close to a miracle for a comeback at this point.

Replacement is your main option. But, hey, look at it as an opportunity to try something new or different!

Plants that could fall into this boat: crape myrtle, heath, heather, osmanthus, hardy camellia, fig, Leyland cypress, caryopteris, newly planted western arborvitae, mahonia, some butterfly bush and possibly anything in the above two categories. I’ve even seen/heard of a few dead Hinoki cypress and KNOCK OUT (R) roses.

Things With Broken or Disfigured Branches: These are plants that had their branches pulled down or snapped off under the weight of the winter’s wet snows and ice storms.

Definitely remove any broken branches that are still hanging, especially ones that could fall on someone.

Cut back to live junctures or to just outside the little ring where a large branch attaches to a smaller one or to the trunk. You don’t want stubs or ragged ends that are prone to infection.

Growth that’s just sagging but not broken is more of a cosmetic issue. Pruning back to more upright growth might fix a few things. Using soft ties to “bundle” up splayed-apart arborvitae is an option for that species.

Otherwise, plants that are now ugly enough form-wise should be removed and replaced.

Plants in this boat: white pine, pear, elm, tulip poplar, willow, silver maple, arborvitae, Leyland cypress, hackberry, ash.

(For more on strong- vs. weak-limbed trees, see my article on “Muscle Trees.”)

Split Tree Bark. Sun-fueled warm-ups in the morning following cold nights caused a fair amount of vertical bark splits on trees.

This happens when the sap freezes overnight, then expands with daytime thawing. The pressure can cause splitting, especially on thin-barked species and usually on the south side of the trunk.

The solution is to do a “bark trace,” which involves cutting the bark back slightly from around the wound. Cornell University has an excellent fact sheet on this. Painting or tarring these wounds is not recommended.

Plants likely in this boat: maple, cherry, apple, blackgum, honeylocust, linden, beech.

Salt-Injured Plants. This is most evident now by roadside evergreens that are browned out only on the road side. This browning was caused by salty slush being plowed onto the foliage.

There’s not much you can do about that at this point, other than to hope new growth pushes out from the browned branches.

If the branches are dead, try cutting them back to live growth and being patient to see if recovery happens. If not – or if it’s going painfully and unsightly slow – the option is removal and replacement, preferably farther back from the road.

For prevention, protect roadside evergreens with a burlap screen over winter or make a note to hose off the plantings (if possible) as soon as you can after each plowing event.

Salt buildup in roadside soil also could lead to worse leaf and needle browning this summer in the event of hot, dry weather. Salty soil is more prone to drying injury.

Plants in this boat: Primarily Leyland cypress, arborvitae and boxwood. Possibly some hollies.