Fall is right around the corner and the morning temperatures have already started to trend downwards. That being said, the Lee County Extension Office received an uptick in calls in August and September this year of homeowners reporting their trees and shrubs dropping their leaves or their plants’ leaves changing colors early. Some of these reports were easy to explain away due to the lack of rain; but some of them were more serious, as there are some species that have not been able to continue to grow in a healthy, successful way. It is anecdotes like these that tell us our community is paying attention to what is happening around them, and that we as a community are observing plants’ response to a changing climate.

Remember from Botany 101 that one of the most important things about plants is their inability to move. As organisms, they have to be self-sufficient as they are only able to grow where they germinate unless they are moved by a human or have developed the adaptation to growing in such a way as to seem like they “move”. There are physiological adaptations, like hormones, that allow plants to respond successfully to environmental stimuli, meaning when something “bad” happens to them, they can recover growth. For example, they have the ability to push out a new flush of growth after getting mowed down on the side of the road. But, plants also can’t “go inside” like us to escape the brutal heat of our NC summers.

Going back to where the weather comes in: The Sanford station for the National Weather Service reported that Sanford received more than one inch less than the monthly average of rainfall (according to data from 1991-2022) in April, June, July and August this year (May was more than two inches above the average). We also experienced more days above 90 degrees than in the last three years from June to August. Disclaimer: Of course, this data only tells a story at one point in the county, the Sanford Airport, as many of us know when we watch the red and orange blips on the radar go around our property on the weather maps; it still gives us a stick to measure by and a way to compare and contrast data through time.

The inconsistent rainfall in Sanford and that it was less rain, coupled with the consistently hot temperatures caused plants and ecosystems to become stressed. One of the ways this stress is expressed is through early “fall color” and leaf drop. It doesn’t mean your plant is dying! It just means your plant is trying to be efficient with its energy and water by shedding a few leaves early. The problem really starts when plants have to do this every year because of weather that is not ideal to support their optimal growth. One of the plants that seem to have taken a turn for the worst is Yoshino Cherries, Prunus x yedoensis.

Moving forward there are a few things you can do to help your landscape in times of stress. First is water when you don’t see any rain on the horizon in the 10-day forecast. Don’t water every day, but water deeply once or twice in that period. The second is to mulch your plants! You can use compost, pine needles or triple-shredded hardwood. Whatever organic matter you can get to shield the soil from sunlight and water loss. Third, do not treat your plants with fungicides or insecticides when we will have days above the 90s. Wait until the evening when it is cooler.

A final note on North Carolina’s changing climate: The overall trend for North Carolina, based on current data and models, is not so much an increasing temperature as an increasing amount of extreme rainfall events that have the potential to swing back to extreme periods of drought. You can read more about it in the Climate Change Report from NC State.

References:

Gardening Tips for Heat-stressed Landscapes

Heat Effects in Farming

Find Sanford Climate Data Here

The Full NC Climate Science Report

Technical Description of How Plants Respond to Heat Stress

Amanda Wilkins is the Horticulture Agent with N.C. Cooperative Extension in Lee County.