Environmental Stress

Don’t Let Dry Soil Follow Your Plants Into Winter!

By Holly McNamara, UConn Plant Diagnostic Lab

This year, Connecticut’s notably dry summer conditions have continued into fall. According to the U.S. Drought Monitor, all counties are abnormally dry for this time of year, and some are even considered to be in a moderate drought. Thus, many trees, shrubs, and perennials are heading into winter low on moisture. These conditions combined with the dry air, low precipitation, and fluctuating temperatures characteristic of Connecticut winters can lead to plant damage if no supplemental water is provided. Many of your plants will benefit from a deep final soak before the ground freezes.

Fall drought stress often doesn’t show up until spring, or even the following summer.Affected plants may appear perfectly normal and resume growth in the spring, using stored food energy. Plants may be weakened or die in late spring or summer when temperatures rise. Browning evergreens, delayed leaf-out, and sudden dieback are common signs of plants that went into winter too dry.

Moist soil is so important in the fall and winter months because it provides insulation to the roots. It may seem counter-intuitive, but properly hydrated soil does a much better job at protecting roots from freezing temperatures than dry soil. Root damage occurs for this reason when plants do not receive enough late-season moisture.

Woody plants with shallow root systems require the most supplemental water during extended dry periods in the fall and winter. Trees in this category include maples, birches, willows, and dogwoods. This category also includes perennials, and shrubs like hydrangeas, boxwoods, and azaleas. These plants benefit from mulch to further conserve soil moisture and buffer the roots from temperature swings. Apply mulch about 2 to 4 inches away from the trunk all the way to the outermost reach of its branches in a doughnut shape.

Evergreen needles up close
Evergreens need sufficient water in dry falls to help prevent winter injury. Photo by Heather Zidack

Evergreens also benefit from fall and winter watering because they do not go dormant in the winter. Evergreens of any age are still actively respiring during the coldest months of the year and will continuously lose water through their needles. If they go into the winter with dry soil, they are more likely to have a difficult spring recovery. This is especially true for those in open or windy areas.

Only water when daytime temperatures are above 40°F, ideally in the late morning or early afternoon so the water can soak in before possible freezing at night. Feel the soil at a depth of 4 to 6 inches to ensure that supplemental water is necessary. Soil should be consistently moist, but not oversaturated or muddy. Stop supplemental watering after the ground freezes because plants cannot absorb water through frozen soil. To water, use a soaker hose to provide a slow stream of water that can penetrate deeper into the soil with limited runoff. If your hose is already stored away for the winter, and your tree or shrub is small, consider drilling a 1/8-inch hole at the bottom of a 5-gallon bucket and filling that with water for a slow, steady stream. If dry weather continues into the winter and there’s little snow cover, additional watering once or twice a month may be needed until the soil hardens.

A final round of watering now can prevent root injury that won’t be visible until much later. Evergreens, deciduous trees, and other landscape plantings will head into winter stronger with a little extra attention this month. Giving the soil one last watering before it freezes is one of the simplest ways to protect your landscape from winter stress.

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at extension.uconn.edu/locations.

This article was published in the Hartford Courant October 25, 2025

Why is My Lilac Blooming in the Fall?

By Pamm Cooper, UConn Home & Garden Education Center

Bumblebees on fall blooming lilacs
Photo by Pamm Cooper, UConn Home & Garden Education Center

Spring-blooming woody plants like lilacs (especially the old, grafted varieties), ornamental cherries, forsythia, crabapples, azaleas and some magnolias set their flower buds for the following year in early summer shortly after flowering.  Usually, flower buds are triggered to bloom by environmental conditions which normally occur after an extended fall and winter cold period, followed by longer days and warming temperatures in spring. It is not typical for these plants to have a second bloom in the fall, but environmental conditions sometimes trigger premature flowering in the fall. Some plants may have only a few flowers rebloom, while other plants may have more flowers open in the fall.  

Some of the reasons for this out of season bloom are extended summer heat and drought conditions where supplemental water is lacking.  Severe early defoliation, especially from certain fungal pathogens, can also contribute to reblooming. The past two springs have been very wet and diseases such as anthracnose and Pseudocercospora spp. leaf spot may have caused leaves to brown, shrivel and drop early. This stresses the shrub and contributes to out of sync rebloom if other conditions are right. Good sanitation practices such as cleaning up infected leaves will be helpful in reducing fungal infections the following year. 

If a plant is healthy and relatively unstressed, the normal seasonal move to cooler weather triggers dormancy. Plants that are deciduous will drop leaves as daylight length and temperature both decrease. Next year’s leaf and flower buds will also remain in a dormant state. Flowering and leafing out will be triggered by increasing daylight and air temperatures the next spring. 

Lilac flowers opening in October
Photo by Pamm Cooper, UConn Home & Garden Education Center

If certain woody plants have been stressed during the growing season, however, the change to cooler weather followed by some warmer weather can trigger some of the flower buds to open prematurely. This false dormancy especially affects flower buds near the tops of old-style lilacs where it is sunnier and warmer. Ornamental cherries may show sporadic flowering all over the tree where there is a southern exposure.  

While fall reblooming of ornamental trees and shrubs can lead to a disappointing floral display the following spring, it is not harmful to the plant. After a less showy spring bloom period, flower buds will be produced normally. If stressful conditions caused by environmental conditions, insect pests or fungal pathogens are minimal, then a second bloom in autumn is unlikely to occur. Gardeners and landscapers can only do so much, and while the weather is out of our control, making sure plants are maintained properly to avoid stress during the summer will go a long way in helping them remain as healthy as possible.  

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at extension.uconn.edu/locations.

This article was published in the Hartford Courant October 18, 2025