Effective Strategies to Safeguard Your Garden During a Heatwave

The reality of climate change is undeniable, and its impact extends beyond human life to agriculture, including home gardens. Growing up in Arizona, I found gardening to be a constant challenge. Now, living in the Pacific Northwest, even here, extreme weather events like 'heat domes' create significant issues, leaving many gardeners in my community facing difficulties.

In my region, gardeners go to great lengths to shield their summer crops, using everything from intricate umbrella setups to white fabric coverings. Watering techniques are a frequent topic of heated discussion in local gardening circles. Below, you’ll find expert-backed tips that truly make a difference in helping your garden not only endure but thrive during intense heatwaves.

Consider using low tunnels and protective shade cloth

Umbrellas are only temporary solutions. With global warming, the weather patterns you experience this summer are likely to recur, so it’s essential to invest in long-term infrastructure. While sheets offer minimal protection, the real game-changer is shade cloth. This durable black fabric should be installed like a canopy over your most delicate garden areas. Available in varying levels of UV blockage, such as 50%, it effectively filters sunlight. You can purchase it by the foot at local garden centers or online retailers like Amazon.

Ensure the shade cloth doesn’t directly touch your plants or vegetables, as proper airflow is crucial. Many shade cloths come with grommets in the corners for easy attachment to trees or fences. If these aren’t available, you can use green steel posts from Home Depot, secured with a mallet, or create a low tunnel using PVC pipe and straps to support the fabric.

Understanding which plants to shield and which to leave exposed is critical. Often, we prioritize the wrong plants. Many gardeners focus on nightshades like tomatoes, eggplants, and peppers. While these can suffer from sunscald (similar to sunburn), they generally thrive in sunlight and heat. Protect them only after securing other more vulnerable plants with leftover fabric. These plants may struggle to pollinate or drop blossoms in extreme heat (above 95°F), but the primary concern during this season is preserving the fruit.

Peas have a short growing season and are typically finished by the time extreme heat arrives. Annual flowers, artichokes, roses, grass, and perennials like lilacs, irises, peonies, and tulips don’t require protection, as they either recover naturally or have already completed their cycle by mid-summer.

Key areas to prioritize for protection

Begin with hydrangeas, as they are highly vulnerable to extreme heat and can easily wither during a heatwave. Berries also need attention, as they face dual threats: leaf scorching and crop failure due to heat damage. This applies to strawberries and blueberries, but especially to cane berries such as raspberries, blackberries, and boysenberries.

Lettuce and cabbage are particularly prone to heat damage, making protective coverage essential. This also applies to other delicate, leafy annuals in your garden.

Consider covering cucumbers during extreme heat to ensure continued pollination and to prevent them from turning bitter. Unlike many other crops, cucumbers may still be producing fruit during this period.

Watering presents its own challenges

The myth that midday watering burns plants has been disproven, but it’s true that roots gravitate toward water. Surface watering during peak heat can cause roots to rise closer to the surface, where they risk heat damage. Water deeply at the root level early in the morning, avoiding overhead watering. Deep watering may reduce the need for daily irrigation. To determine when to water, check the soil moisture by feeling a few inches below the surface—this will guide your schedule.

Overwatering is a real concern, especially for plants like cucumbers and tomatoes. Even if they survive the heatwave, they might end up with poor flavor or issues like blossom rot. Consistent watering and proper nutrient supply are crucial. If you fertilize your plants weekly, apply it early in the day and water it in thoroughly. Avoid surface-level treatments during extreme heat.

Mature plants have a higher chance of surviving extreme conditions

Heatwaves during the transition to fall gardening are particularly challenging. Established plants with deep root systems can endure better, but young seedlings require extra care. This might involve providing shade or supplementing drip irrigation with hand-watering to ensure their survival.

It’s often overlooked, but even large, well-established trees and shrubs need deep watering a few times during the summer. This means a slow, prolonged soak over several hours to allow water to penetrate deeply. Remember, the roots of mature plants extend far beyond the base, so water should be applied over a wider area. Soaker hoses are ideal for this purpose.

Adapt your gardening practices

As a gardener, you’re likely aware of your planting zone, but you may not realize that global warming has caused some areas to shift zones. This change is permanent, so when planning your garden, consider incorporating structures for shade and drip irrigation to adapt to the new conditions.

Carefully consider plant selection and placement: Opt for species that can withstand heat and drought. Pay close attention to whether plants prefer shade or sun, and position them accordingly.

Encourage your plants to become water-efficient by avoiding overwatering. This practice helps them develop robust root systems, reducing their overall water needs.

Mulch extensively

Mulch plays a critical role in maintaining soil moisture and protecting plants from heat. Applying a thick layer of straw, wood chips, or organic mulch can transform your garden beds. It retains soil moisture effectively. Ensure mulch is kept away from plant and tree bases to prevent disease, but otherwise, apply it generously. Don’t forget, free wood chips are often available through services like Chip Drop.

Harvest crops promptly to avoid overripening

All edible produce should be harvested as soon as possible. Even crops typically left to ripen on the plant should be picked earlier than usual to prevent them from being damaged by excessive heat. This applies to tomatoes, eggplants, peppers, green beans, cucumbers, and berries. Regularly inspect your garden during cooler times, such as early mornings or evenings, to gather ripe produce.