We’ve had some extreme heat in Virginia this summer, and we’re not alone. Extreme heat events are on the rise across the United States. Many gardeners know high temperatures can significantly impact plant growth, causing issues like blossom drop, increased disease problems, and reduced production. Unfortunately, high heat can also affect your freshly picked harvest.

In this post, we’ll talk about how heat may impact your freshly harvested produce and what you can do about it.

How Does Heat Harm Your Harvest?

High temperatures can impact the flavor, texture, nutrients, and appearance of your freshly harvested crops.

Increased Respiration: Hot produce undergoes a metabolic process to consume oxygen and stored sugars and carbohydrates, releasing carbon dioxide, water vapor, and heat. This process can make your produce less sweet, reduce its nutrient value, and change its texture.

Cellular Breakdown: High temperatures can cause cellular breakdown, which causes produce to rot more quickly. The longer your produce stays hot, the lower its shelf life will be.

Wilting: Hot weather harvesting can result in rapid water loss, causing wilting and soft textures in vegetables like collards, cilantro, lettuce, arugula, and basil.

Time Your Harvest

As you’d suspect, to keep your produce as fresh as possible, you want to harvest when temperatures are as cool as possible. Early mornings or evenings, when the temperatures are lower, the field isn’t in direct sunlight, and the plants are more hydrated, are the best times to pick your crops. Cooler, cloudy days can also be a good choice if they align with your harvest needs.

Immediately Cool Your Harvest

When you harvest your produce, you want to remove any field heat as quickly as possible. For most crops like broccoli, lettuce, and carrots, the best way to do this is to wash them in cool or cold water. For sensitive crops like lettuce, you can rinse off any dirt in cool water and then place them into an ice bath. This will help the leaves cool off and absorb moisture, keeping them crisp and flavorful longer.

Thoroughly dry any crops you wash or hydro-cool in an ice bath. Damp conditions can encourage the growth of mold and bacteria. A salad spinner is helpful for drying greens.

A few hot-weather crops like artichokes, melons, peppers, and tomatoes shouldn’t be tossed into an ice bath or washed immediately after harvesting. For these, move them into a cool space as quickly as possible. Ideally, somewhere with AC.

Move Your Harvest into the Shade

Move your produce out of the sunlight as quickly as possible. For large summer harvests, it’s best to carry each container of produce into the shade as soon as it’s full before moving on to the next one.

You can also use easy-ups or other shade canopies to temporarily shade the area you’re working in. Prolonged exposure to sunlight can impact your produce’s flavor, texture, and shelf-life.

Store Anything You Won’t Use Immediately at Appropriate Temperatures

Different crops keep best at different temperatures. Some crops like cauliflower, parsnips, and spinach keep well at 32°F. Others, like green beans, watermelons, and tomatoes, will store longer when kept at warmer temperatures between 40°F and 60°F. If you want to keep produce in cold storage, be sure to look up your crop’s exact storage requirements.

Check out the Cornell University Cold Storage Chart & Reference Guide for specifics.