If you thought that trees, shrubs and perennials go dormant in the winter and don’t need any water, think again.

While the fall may signal the end of summer watering, the gardening season certainly isn’t over. “Roots are still active, even after leaves drop,” said Sharon Yiesla, a plant clinic assistant at the Morton Arboretum in Chicago, Illinois. “The soil cools off much more slowly than the air does, and as long as it’s warm, the roots will continue to absorb water.”

Yiesla says that it is especially important to water in the Midwest this year, since late summer and autumn have been very dry in northern Illinois. The levels of rain this year have been low across many parts of the country, according to reports. For example, the Chicago area has received less than half as much rain as its yearly average.

Going into winter with dry roots can cause trouble for trees and plants in the spring. If the roots are damaged from drying out in the fall, they can’t absorb water in the spring. “Evergreens need stored-up water to make up for what they lose through their leaves, especially in the cold dry air of winter. People don’t realize that water is leaving those needles all winter long,” Yiesla said. “When evergreens don’t absorb a sufficient water supply in the fall, their needles can dry out, turn brown and die.”