I’ll save you a read: right now, it feels like the heat and drought are winning. To me as a gardener, it also feels like it's winning.

If you have stepped outside to check on your garden or crops lately, you’ve probably noticed leaves crisping at the edges, flowers dropping, and a general sense of fatigue across the landscape. As a gardener, it can feel thoroughly discouraging. But to understand why our yards look so battered in late summer, it helps to look at how extreme heat creates a triple threat for plants, pollinators, and the humans who tend them.

The Botany of a Heatwave: What Heat Does to Plants

To grow and stay healthy, plants rely on three core physiological processes: photosynthesis, respiration and transpiration. Photosynthesis is the process of using sunlight, water, and carbon dioxide to manufacture their own food in the form of sugars. Respiration turns those manufactured sugars into usable energy to fuel daily growth and defense. Finally, transpiration pulls water and nutrients up from the soil through the vascular system, and releases water vapor through the leaves to cool down (much like human sweating).

Here is the bad news: for most temperate plant species, photosynthesis begins to break down at temperatures above 86°F (30°C). When air temperatures cross this threshold, microscopic pores on the leaves (stomata) slam shut to conserve water. This halts transpiration and stops photosynthesis in its tracks. Without water moving through the plant, leaves wilt, soil nutrients remain locked in the ground, and energy production stops.

To make matters worse, heatwaves impact plants round-the-clock.

Warm nights mean no rest for our plants. When nighttime temperatures stay stuck in the upper 70s, plants' respiration runs on overdrive all night long, burning up precious sugar reserves created during the day without making any new ones. This essentially starves the plant because it is cannibalizing sugars it would save for other processes. Starved of energy, plants stop producing natural defensive chemicals, leaving them sitting ducks for opportunistic pests and fungal pathogens.

One of the worst things about the heat is our fruits and vegetables are less productive and less nutritious. Ever wonder why your summer tomatoes turn a dull, pale yellow-orange instead of a rich, vibrant red? High temperatures inhibit the production of lycopene, the pigment responsible for that classic red color! When energy reserves run dangerously low, plants enter survival mode. They will intentionally drop their flowers and young fruit—essentially aborting "the babies"—because they simply do not have the resources to support reproduction and stay alive at the same time.

The Entomological Toll: What Heat Does to Pollinators

Pollinators are critical to plant reproduction in most of our plants, including our favorite fruits and vegetables, like strawberries, tomatoes, blueberries and pumpkins. Pollinators are a highly diverse group of organisms. Most folks think of honey bees, but there are so many more native pollinators in our North Carolina ecosystems. Bees, butterflies, moths, wasps, flies and beetles are all pollinators and there are hundreds, if not thousands, of species in each group, so it is hard to generalize the impact of drought and heat on pollinators because of their diversity.

While some insects thrive in warm weather, prolonged heatwaves combined with drought create severe challenges for the pollinators. It can be challenging for researchers to truly understand all of the effects because some of these critical organisms are challenging to study in the first place!

Fascinating research from researchers at four southeastern universities, including NC State University, showed that bumblebee colonies—particularly those with above-ground nests—can suffer heavy casualties during extreme heat. Instead of foraging for food, adult bees are forced to stay inside the nest and continuously fan their wings to keep colony temperatures below lethal levels.

A general heat and drought can lead to a nectar drought. Heat- and drought-stressed plants produce significantly less nectar and pollen. Nectar is the primary fuel source for adult pollinators. When flowers dry up, bees and butterflies must fly farther and expend far more energy for a fraction of the caloric reward. So, even though the temperatures might be ideal for movement, it doesn’t improve the efficiency of nectar production to keep up with the insect activity.

The Human Element: Heat Hazards for Farmers & Gardeners

We cannot talk about the garden without talking about the people who tend it. The NC State Climate Office paints a grim picture of extreme heat: "According to the National Weather Service, over the 30-year period from 1991–2020, there were an average of 141 deaths per year [in the U.S.] from heat-related causes. This is more than any other type of weather event during this period." For context, extreme heat claims more lives annually than hurricanes, tornadoes, or floods. Working outside in North Carolina's summer heat index is no joke.

To protect yourself while caring for your land:

• Listen to Advisories: Check weather apps daily and heed Heat Advisories or Excessive Heat Warnings from the National Weather Service.
• Shift Your Schedule: Do heavy outdoor chores during the coolest hours of the day (early morning or dusk). Avoid working during the peak heat window between 11:00 AM and 4:00 PM.
• Hydrate Proactively: Drink water before you feel thirsty, and incorporate electrolyte-supplemented beverages to replace lost salts.
• Take Mandatory Shade Breaks: Take a 10- to 15-minute break in the shade or air conditioning for every 45 minutes of outdoor work during high-heat periods. As the heat increases, decrease work windows between breaks.

How Can Gardeners and Farmers Help?

I always say "a healthy plant is a resistant plant," but during historic heatwaves, our goal shifts from helping plants thrive to helping them survive.

1. Prioritize Your Water: Collect rainwater when available, and prioritize supplemental watering for high-value crops, fruit trees, and young perennials rather than struggling annuals.
2. Invest in Shade Cloth: Vegetable gardens—especially tomatoes, peppers, and leafy greens—benefit tremendously from a 30% to 50% shade cloth stretched over the beds. This lowers ambient temperatures enough to keep photosynthesis moving and prevent fruit scorch.
3. Protect the Soil: Keep bare soil covered with 2 to 3 inches of organic mulch (pine straw, leaves, or wood chips) and top-dress with compost annually. Soil covered with mulch stays significantly cooler and retains precious moisture far longer than exposed dirt.
4. Practice "Garden Triage": Evaluate your plants with a critical eye. It is completely okay to let unthrifty or heavily stressed annuals go so you can focus your time and water on plants critical to your landscape.
5. Plant for the Future: Note which species and varieties in your yard and local communities handled the heat like champions this year, and consider expanding those drought-tolerant rockstars in your fall planting plans!

Get In Touch!

Amanda Bratcher is the horticulture agent with N.C. Cooperative Extension—Lee County Center. Have questions about keeping your garden alive through summer heat or taking care of your soil? Reach out to our office at 919-775-5624 or visit our events page to sign up for upcoming fall gardening programs!

This article originally appeared in The Sanford Herald. You can read more articles from the Herald on their website.

Resources

Plant Growth and Pollinators

Plant Physiology Section in the Extension Gardener Handbook

How Higher Temperatures Can Benefit (or Devastate) Bumble Bee Populations

Nesting biology shapes climate vulnerability of social bees (Bombus spp.)- Mullan, et al.

Veggies and Herbs Made in the Shade: A Growing Season Calendar for North Florida Fenneman

Weather in NC

NC State Climate Office

Subscribe to the NC State Climate Office’s Blog (it is pretty cool but also practical)

March 2026 Allison Whitaker and Corey Davis, Growing Season Scenarios Plants Pests and Pathogens Webinar from NC State Climate Office; July 2025 Lucy Bradley, Climate Resilient Strategies for Home Gardens & Landscapes (Free)

Heat Index Climatology

Heat Zone Comparison 1980 - 2099

Growing Seasons Article from National Geographic

Sustainable Gardening Institute Plant Heat Zones Map

Be Heat Safe

Heat.gov- a great resource for heat safety and they have a GREAT app

Heat Action Plan Toolkit from NC Department of Environmental Quality

Planning for Extreme Heat Cohort Program

They Call It Stupid Hot for a Reason (from Nautillus)