One of my most memorable gaffes in the garden was the time I sprayed a Japanese cedar with horticultural oil. That would take care of the mites, I thought. Instead, it nearly took care of the tree. The oil stripped the cedar’s needles of their waxy coating just in time for some freezing weather. The entire foliage turned brown, and I spent the winter looking at a 12-foot evergreen that appeared dead. My urge was to rip it out.
A gardening friend told me to wait to see whether it re-foliated. And lo, by the following May it was verdant with fresh growth. It is now 40 feet high and looking as hearty as its two companions.
The moral is that plants that seem dead may not be. In early spring, this misdiagnosis enters peak season. It is the time of year when trees and shrubs look their most winter-battered and when the gardener is most eager to see everything lush and healthy.
This spring will be worse than most, especially for broadleaf evergreens. Evergreens need to be fully hydrated before the ground freezes to minimize wilting and leaf scorch when frigid temperatures and winds arrive. But plants in the Mid-Atlantic entered winter in near-drought conditions and then had to endure a prolonged freeze at the end of the year.
The result is already evident — a great deal of browning and scorching on such popular plants as azaleas, cherry laurels and camellias.
David Yost, a horticulturist at Merrifield Garden Center in Fair Oaks, Va., is already fielding questions from customers and expects a lot more. “When the temperatures get warmer and people are out and become aware of this damage, we’ll see many more” anxious inquiries, he said.
I compared notes with Yost and several other plant experts, and the one abiding piece of advice is this: Wait.
Yost tells the story of his own winter-burned camellia where all the leaves turned brown and began to fall. He had already ordered a replacement plant when he noticed that the “dead” plant was producing new growth. This wasn’t until late May. By the end of summer, the camellia was fully foliated.
“Our message,” he said, “is basically do nothing.”
With woody plants that appear dead, there is a quick way to gauge their vitality: If you scrape the bark, either with your thumbnail or a blade, a green layer beneath suggests all is well. (If one branch tests brown, check others.) But even if it looks dead, give it a while before reaching for the shovel.
In the garden, false death comes in a number of forms, but the general advice is the same: Wait a few weeks and see what happens. By late May, you will know what is alive and what isn’t.
Unlike hibernating deciduous plants, conifers and broadleaf evergreens must endure the full brunt of winter; this includes desiccation caused by frozen soil, de-icing-salt injury, wind burn, sun scorch and the general damage to tissue from hard freezes. The damage can be particularly conspicuous on broadleaf evergreens, and expect to see various degrees of injury on azaleas, rhododendrons, some hollies, aucubas, cherry laurels, nandinas and camellias, to name the most obvious.
The damage ranges from brown edges to entire leaf browning and stem dieback.
Plants with damaged leaves but with stems intact will develop new foliage this spring. Those with dead stems are likely to produce new shoots either from the base of the plant or at the point on a branch below the freeze damage. There is no need to cut off leaves that are brown. Beyond getting exasperated by the tedium of the task, you risk damaging the replacement buds at the base of each leaf. The bush will drop affected leaves when it’s ready.
Nandinas tend to concentrate their foliage on the upper half of their stems, and this legginess is accentuated after a harsh winter when lower leaves shrivel and drop. The solution is to remove some canes entirely and cut others down to about 12 inches above the ground. This will promote thicker, lower growth in the months ahead. Yost cautions against drastic pruning of damaged plants, which will remove stored energy in latent buds and further stress them.
Deciduous trees and shrubs
Some small trees and shrubs are prone to damage to their branches after a harsh winter, but because the roots are more protected than the top growth, many plants will re-sprout from the ground. This may mess up their shape and diminish their presence for a year or two, but the plant should come back strongly and successfully from an established root system, especially with some gentle shaping from the gardener.
In the Mid-Atlantic, the obvious candidates for this type of injury are hydrangeas, fig trees and buddleias. You could add some crape myrtles, loropetalum and vitex to the list. A damaged fig will regrow as a multibranched, large shrub and will take two or three years before it fruits again. The crape myrtle and buddleia should flower this summer.
Most mophead and lacecap hydrangeas that are top-killed won’t flower this year. The exception will be popular new varieties that have been bred to bloom on new growth, but even with those the display will be diminished. Allow them to re-sprout from the ground. Pay attention to frosts next spring after they have sprouted and cover them at night if needed.
Rosemary, lavender and culinary sages are vulnerable to the type of winter we just had. I have seen lavender plants in protected urban locations looking fine and others beaten and ragged, but I think most will come back if their owners resist the urge to tidy them by cutting them back. Wait until you see new growth next month, and then trim back dead wood at that point. Avoid a hard pruning and leave emerging shoots to develop. The same general advice holds for garden sage. Wait to see what grows and then do some grooming. Some ornamental sages — Salvia microphylla and S. guaranitica varieties — may have just squeaked by in protected sites. Wait to see what re-sprouts.
I suspect that most rosemary plants hereabout will be dead this spring — you should know in three or four weeks. Some varieties are hardier than others, but any winter temperatures in the teens or below will put them in peril. Once I’ve established that they’re kaput, I simply rip them out and plant afresh. Young, new rosemary plants should be hardened off — conditioned for cool spring nights — and planted in free-draining and enriched soil. They will soon bulk up and, if planted in spring, be ready for their first winter come December.
Some plants take longer than others to wake up in spring, especially after a cold winter. Tardiness might give the impression that they have given up the ghost, but again patience is the key. According to a 2014 study, the leaf-out dates of woody plants can vary by as much as three months, with trees being later than shrubs, conifers later than flowering plants and even the diameter of a plant’s plumbing affecting when it begins to grow.
One popular late starter is the crape myrtle, which may not stir until late April or early May. Another is the native fringe tree. Perennials, too, can take their time. Because they grow directly from the ground, their appearance is directly related to soil temperatures, which vary by soil type, drainage and location.
Some hosta varieties appear in March; others appear a month later. The hardy hibiscus of late summer is notoriously tardy to appear in spring. Horticulturist Kata Kress Wallace of Hoffman Nursery in Rougemont, N.C., reminded me that baptisias are also slow to emerge. She said Solomon’s seal can be late, too, or even skip a whole year of top growth after a harsh winter, if newly planted.
What to do
The advice with winter-damaged plants is not to act, which is frustrating to the nurturers among us, but here are three steps that will help the plant and gardener alike.
Water: Give damaged plants one good watering and then monitor the soil conditions as the spring warms up. If it remains dry, water every week or so. You want the soil to be neither bone-dry nor saturated.
Mulch: A light mulch will help retain soil moisture and keep competing weeds away. Let it be a layer of no more than two inches and don’t pile mulch against trunks or stems. Shredded and half-rotted leaves — leaf mold — are perfect for this and will break down and feed the soil quickly.
Feed: A light feeding of slow-release fertilizer will help plants grow. Whether you use organic or chemical feed is your choice, but follow the directions and err on the side of too little rather than too much.
And remember, there will be enough general flowering and leafing out in the weeks ahead to keep your eyes — and mind — off winter’s battered survivors.
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