What do all of these moisture fluctuations mean for our gardens?

The results of the earlier rain deficit may not be noticeable, but many trees and shrubs were stressed by inconsistent moisture, not only this year but in the last several years. Both drought and extreme wet conditions can have a profound impact on soil health. The two extremes—too dry, too wet—prevent roots from taking in nutrients and impacts microbial activity. Microbes play many roles, including the breakdown of organic matter and helping plant roots extract nutrients from the soil.

One of the most important things a gardener can do to address both of these extremes is to routinely add organic matter to planting beds. This helps condition and loosen the soil so that it retains water when needed, but also moves moisture deeper into the soil so it’s not waterlogged.

Hot, dry, and sopping wet

Dry soils and waterlogged roots produce similar symptoms: Leaves may wilt, droop, curl, or turn yellow. Healthy plants move water (and nutrients) from their roots into the leaves where it evaporates. The leaves of some plants, like Annabelle hydrangea, wilt on hot, sunny days to help reduce evaporation, but they perk back up at night.

When the soil is so saturated with water that it displaces tiny air pockets that roots require, the plant may also wilt. Roots need oxygen, and when the soil takes days to dry, the roots can rot, causing plant stress or death.

Plants are largely made of water. An herbaceous plant may contain as much as 80 to 90 percent water—those juicy tomatoes, cucumbers, and melons are good examples. A woody plant can contain about 50 percent water. But with several inches of sudden rain, tomato skins may begin splitting because of excess moisture.

Annuals, like petunias and fuchsia, are often the first to show stress from drought or soggy soil. They may be stunted or quick to flower, produce seeds, and then fail to thrive. Like turf grass, an annual has roots that are shallow compared to perennials and woody plants, and a lack of moisture can result in shorter plants with fewer, smaller leaves. If there's too much moisture, the roots will suffocate.

Extremely dry or wet soil also affects a plant’s natural defenses and increases susceptibility to disease infections and insect invasions, including borers, bark beetles, canker, and root disease fungi.