Based on 126 years of statewide average rainfall data, 2020 was the second wettest year on record, with 2018 being the wettest. 2021 has just gotten started, but it looks like we may be in for another record-breaking year in terms of heat and precipitation. This is not good news for anyone with a yard.
Everyone knows that for plants to grow and stay healthy, they require water and sunlight. However, it’s a lot more complicated than that. Excess water in the soil leaves no room for oxygen, a key component for plant metabolism. In school, children learn that humans breathe out carbon dioxide and breathe in oxygen, whereas plants “breathe” in carbon dioxide and release oxygen, but plants actually require a significant amount of oxygen as well, and they take it in through the roots as well as through the stomata (small pores) in leaves. When we have excessive rain, the soil is unable to drain fast enough and becomes waterlogged, which suffocates plant roots. After some period of time, the roots will begin to die.
The length of time a plant can survive in waterlogged soil depends on the species and the conditions under which it evolved. Some trees such as river birch, sycamore, and bald cypress naturally grow near (or in the case of bald cypress, in) bodies of water, so they can handle having “wet feet”. Other plants, such as those that grow in high altitudes where the air is less humid and the water table is lower, like azaleas, mountain laurel, or pasqueflower, will die quickly when exposed to boggy conditions. If you have plants in your landscape that aren’t tolerant of wet soils, you can expect there may be some losses this year. The larger the plant, the longer it will take to show decline, and for large trees it can actually take up to several years to die from lack of oxygen in the roots.
Another issue caused by wet weather is increased fungal diseases. Wet weather triggers spore production in fungi, and many fungal pathogens are spread through water droplets splashing between plants and into injured areas or new growth that has less protection than mature branches or leaves. To reduce infections, make sure you only prune during dry weather, and prune off broken branches that could provide an opening for disease to take hold.
The climate in North Carolina ranges from the colder, drier mountains in the west through the swampy coastal plains in the east. The piedmont in the center of the state has historically been the best of both worlds where a broad range of plants could be grown, but with warmer and wetter conditions each year, that may be changing. For established plantings, there isn’t much that can be done to protect plants from wet weather, but there are some things to take into considerations when adding new plants. Here are some tips for future-proofing your garden: