Winter dieback is the loss of stems, shoots, buds and sometimes entire branches of trees and shrubs due to winter cold and winds. Most common are shoots and buds of deciduous shrubs with flower buds being the most susceptible winter injury.
As mentioned earlier, watering plants several hours before a freeze is the first defense against damage. During a temporary cold snap, cover entire shrubs with burlap, sheets or blankets for insulation.
Other plants, like trees and shrubs, become dormant, or rest in the winter. Tree and shrubs, along with herbaceous (soft-stemmed) plants live for two years or more and are referred to as perennials. They store their food, or sap, in their roots as mentioned above.
As winter progresses, the ground freezes and the sun and wind evaporate more water from the leaves or needles than the plant can uptake to replace it, and the plant gradually turns from green to brown, bronze, or even orange or purple.
Most leaf drop of deciduous trees and shrubs occurs by mid-December. Some plants will start dropping leaves as early as the second week of November while others drop leaves later. But of course, much of that depends on the weather and tree health. If it's unusually cold early, leaf drop is early.
Late winter is a good time to prune most plants. Because plants and their pests are dormant this time of year, pruning cuts can be made without the risk of pests and pathogens entering the tree through the wound.
Despite the fact your plants are dormant and brown, they should still be watered periodically. Plants that remain dehydrated in winter months often don't survive until spring. Not only does this create extra landscaping costs in warmer months, it can actually damage your plumbing.
A brown shrub could still have some live growth and will bounce back with some TLC. Inspect your shrubs for any sign of green growth. If your shrub turned brown because of weather conditions, it can potentially bounce back as the extreme weather subsides.
For some shrubs (azaleas, abelias, hollies and others), a hard renovation pruning will allow the entire shrub to regrow evenly. In other shrubs, including many (but not all) needled evergreens, the loss of a section is never fully recovered because of the way they grow.
Pests or disease: Insects like borers or a disease like boxwood blight can cause shrubs to change color. Water problems: Both too much and too little water can stress a shrub out and cause it to turn brown.
Symptoms of freeze damage include shriveling and browning or blackening of damaged tissue. Damaged growth usually becomes limp. Eventually, damaged or destroyed leaves drop from the tree or shrub. Fortunately, trees and shrubs have the ability to leaf out again if the initial growth is damaged or destroyed.
“Most garden plants are tolerant of a brief freeze period—as long as the roots are still healthy, you'll typically see them recover just fine in the spring,” says Lindsay Pangborn, Gardening Expert at Bloomscape.
Four to six inches of bark mulch, straw, or shredded leaves - especially when placed around newly planted trees or shrubs - keeps soil temperatures constant and prevents plants from heaving out of the ground due to cycles of freezing and thawing.
Shrubs are fairly permanent elements of your garden. They are either deciduous, which means they go dormant and lose their leaves in winter, or evergreen, which means they don't go dormant and do retain their foliage all winter.
Just like humans, plants get cold and need protection from frigid temperatures. Evergreen shrubs can withstand flurries, but heavy snow and other hazards of the upcoming season can wreak havoc on these workhorse yard plantings.
Fortunately, trees and shrubs can be fertilized heavier in the fall and winter months without the risk of leaf burn. This is because, when temperatures start to drop, plants stop sending water and nutrients up to the leaves.
If the roots cannot pull up any water, the water that transpired from the leaves cannot be replaced; therefore, these cells die causing brown tissue. Once the snow melts, you may observe noticeable differences in shrubs or plants that were partially snow-covered.
Removing dead or dying branches will not only help to prevent the spread of disease to other parts of the plant, but it will also help the tree or shrub to focus on producing new, healthy growth. Older wood that no longer flowers can also be removed.
Rejuvenation pruning, also called renewal pruning, involves cutting some types of shrubs almost down to the ground, leaving only 6 to 24 inches. Done every three to five years, this extreme method of pruning can indeed rejuvenate an overgrown or misshapen shrub, just as the name implies.
There are several reasons for shrubs to have brown leaves and dead branches. These include: Extreme temperatures: A sudden cold spell can shock the leaves into turning brown. We commonly call this winter burn or winter damage, but it can also happen during a heat wave.
One option is to prune them back over a three-year period. Begin by removing one-third of the largest, oldest stems at ground level in late winter/early spring (March or early April). The following year (again in March or early April), prune out one-half of the remaining old stems.
Most outdoor plants can go without water for about a week. Container plants are the thirstiest. Most need to be watered daily.
When the air and soil temperatures consistently fall below 40 F, it's time to stop watering. The ground can't absorb water once the top few inches freeze. Continue to water your plants up until this point so they're as well-hydrated as possible going into winter.
The best time to water plants is in the morning or evening.
Morning watering is actually preferable to evening watering as the plant has time to dry before the sun goes down. At night, water tends to rest in the soil, around the roots, and on the foliage, which encourages rot, fungal growth, and insects.