15 Ways to Protect Your Plants From Extreme Heat

Weird weather is becoming the norm these days. This presents a challenge for gardeners, who must stay on top of changing patterns to maintain a garden full of thriving plants. One issue that is becoming (sadly) far more common across the world is frequent heat waves. How do you protect your plants from extreme heat?

Most well-cared-for plants will manage just fine on a few hot days, but heat waves with prolonged periods of abnormally hot weather can negatively impact your garden over time.

It’s important not to panic in these situations and fuss over your crops to the point where you end up harming rather than helping. Instead, you can employ these few strategies to provide short or long-term relief to keep your garden safe and happy in sweltering weather.

Understand Your Climate

The first step to mastering gardening in a heat wave (and, to be honest, gardening in general) is understanding your climate. This doesn’t just involve a general awareness of temperature changes. You must understand how hot your region gets and how long the temperatures will remain high.

Keep an eye on your local weather forecasts and research the average high temperatures during summer and the duration of heat waves.

• The Old Farmer’s Almanac has a Weather History Archive providing dates back to 1945!
• The National Weather Service also has a localized weather history tool and temperature graphs.

Considering the erratic weather in recent years, this is bound to change. Still, general awareness of the conditions, instead of not considering them, will help you shield your garden from damage and better prepare you when extreme heat arises.

By taking the time to understand your local climate, you’ll equip yourself with the knowledge required to give your garden the best fighting chance during sudden bouts of extreme heat. Plants are usually quite resilient, and if you start with the right strategies in place, the effects of extreme heat will be far less damaging.

Plant In The Right Position

If you live in a region known for scorching summers, the location of your plants can decide whether you have a vibrant and healthy garden or a sad and withered one. Under normal circumstances, giving sun-loving plants the brightest spots in your garden is best. But when the summer sun is unusually intense, even sun lovers can struggle.

I like to start by observing how the sunlight moves across the garden before I plant anything. Understanding where shadows fall throughout the day and the times they change will identify the perfect spots for planting.

Be sure to consider the change in seasons, too. For example, I installed a new bed that looked quite sad in the fall because I didn’t consider the sun’s movement when I planted it in spring.

When it comes to extreme heat, the most important observation is when and where the harsh afternoon sun hits the hardest. Then, avoid planting vulnerable plants in those spots and pick tough plants known to withstand heat well instead. Many sun-loving plants (tomatoes are a great example) can still benefit from a little afternoon shade when the temperatures rise to extreme levels.

The east-facing areas of your garden usually receive morning sun and afternoon shade if you can plant there. Alternatively, consider planting vulnerable plants under the dappled shade of larger, heat-resistant plants or installing a temporary shade cloth (discussed later).

Water Deeply

If you’re impatient or short on time and like to water quickly, you may want to reconsider your practices in the scorching heat.

When you lightly water, moisture remains near the surface, and it can evaporate quickly under the harsh sun. This encourages plants to develop shallow root systems as they stretch towards the water source rather than downward into the soil. Plants become more vulnerable to heat stress in these cases as they cannot access deeper moisture reserves in the soil.

Luckily, the solution is simple. Whenever you water, make sure you water slowly and deeply, penetrating the lower levels of soil to completely saturate it and encourage the roots to grow downwards. It may be a little more time-consuming, but plants with deep roots are much more resilient and capable of withstanding dry spells and extreme heat, making it well worth the effort.

Of course, how deep ‘deeply’ is will depend on the plant species and your garden conditions. But generally, it’s best to soak the soil until it begins to run off, wait until it seeps in, and water again to reach the lower soil layers. A soil moisture meter can also help you monitor how deeply you are watering.

Watering in this way takes a little more time and attention, but it can pay off significantly in plant health and resilience. Your crops will be more robust, ready to take on the scorching summer heat no matter what the weather throws at them.

Water At The Right Time

The timing of watering may not seem to matter too much, but when temperatures are high, timing is crucial. Watering during the day’s peak heat might seem like a good way to offer plants a quick cool-down, but it’s not the most effective strategy for long-term moisture retention.

Watering in the middle of the day causes more water to evaporate before the plants get a chance to absorb it. If you’re watering while the sun is high, you lose a large portion of that water to the atmosphere, watering less effectively.

The ideal time to water is in the cool hours of early morning. This allows the water to penetrate deeply into the soil and reach the roots, giving your crops a proper drink before temperatures increase. As a bonus, excess water on the plant’s foliage can dry off before the sun gets too intense, reducing the risk of fungal diseases.

If early morning watering is not feasible (either due to your schedule or simply because you don’t like getting up early), the next best option is to water in the late evening. Ensure you water at the base of the plant and avoid the leaves, as leaving them wet overnight can also invite unwanted diseases.

I’ve learned through many hot summers that keeping an eye on the forecast can also be incredibly useful. If a cooler day is predicted, take advantage of the forecast and give your plants a thorough watering rather than watering on hotter days. This saves water from unnecessary evaporation and prepares your garden for upcoming temperature increases.

Avoid Overwatering

Once you notice signs of heat stress, drenching your plants with water while attempting to bring them back to life is tempting. Unfortunately, this will usually do more harm than good. The line between hydration and overwatering is fine, and it’s crucial not to let the panic of scorching temperatures tip you over it.

Extra watering when your plants don’t need it isn’t a solution for extreme heat stress. Instead, it can lead to new issues like root rot and fungal diseases, which can be just as destructive as the heat stress you’re trying to combat. Excessive water can also limit airflow around the roots, causing them to suffocate.

One of the most common signs of overwatering is yellow leaves. Unfortunately, yellowing can also be a sign of underwatering, creating serious confusion among new gardeners. Simply press your fingers into the soil to test the moisture levels. If it’s moist, your plants have enough water to survive. If it’s dry, then it’s likely time to water.

Whenever you’re faced with soaring temperatures, don’t just ramp up the watering and hope for the best. Strive for a balance that keeps your plants adequately hydrated but not waterlogged.

Install Drip Irrigation

Extreme heat is tough to manage for occasional gardeners who can’t spend several hours a day keeping an eye on their plants (that’s most of us!) Watering a few more times a week than usual isn’t always feasible when you’re busy. That’s where drip irrigation comes in. 

These practical systems are designed to deliver water directly to where it’s needed most – the roots– ensuring they receive enough water while limiting water usage. By slowly releasing water near the roots, they ensure that the water doesn’t merely sit on the surface where it can rapidly evaporate.

As a bonus, drip irrigation also aids in preventing diseases caused by water-splashed foliage, maintaining the health of your plants while keeping them hydrated. Depending on your system, the valves can be adjusted to control the amount of water each plant receives, making it easier to cater to the specific needs of different plant varieties.

Installation can be time-consuming and pricey, and while many DIY options are available, it does take some work. However, once installed, the system is pretty straightforward and can even be automated with a timer, making your watering chores less of a hassle.

Make Use of Mulch

When gardening regularly in extreme heat, mulch should be your new best friend. An often-overlooked aspect of gardening, mulching has many benefits that extend far beyond aesthetics.

Mulch is spread on top of the soil to maintain moisture, regulate soil temperature, and suppress weed growth. You can use organic materials like straw, wood chips, or compost that improve soil health as they break down.

That’s just the benefits of mulch on a regular day. But why is mulch so crucial for your garden during extreme heat? The layer of mulch creates a barrier that reduces the intensity of the sun’s heat on the soil, helping to keep the roots relatively cool.

Simultaneously, it locks in the soil’s moisture to limit evaporation. When water is a precious commodity, especially during heat waves, you want as much moisture to remain in the soil as possible. A layer of mulch can cut evaporation rates dramatically, leaving a lot more water in the soil for your plants to absorb.

Spread a layer of mulch about 2 inches thick. Less than this amount may not limit evaporation or regulate soil temperature. But any more, and you could end up with a soggy covering prone to mold growth. As the mulch decomposes, it will naturally become thinner, so replenish it as needed.

Grow Groundcovers

If you don’t want to deal with the maintenance of mulching, you could always grow living mulch instead – groundcover plants.

These low-growing plants spread quickly to inhibit weed growth and provide an additional protective layer between the harsh sun and the tender soil, effectively shielding it from the sun’s rays as mulch does. As they sprawl across your beds, they cast a shadow on the soil surface beneath them, lowering the temperature and maintaining much-needed moisture.

From an aesthetic perspective, groundcovers can also bring something extra to your garden design, filling in empty spaces and controlling soil erosion in a practical and pleasing way. Creeping sedums are a personal favorite and great for heat tolerance, but there are hundreds of options to try.

When establishing a ground cover, consider the local climate, your garden’s conditions, and the plant’s specific needs. Some groundcovers prefer shady spots and won’t handle full sun and extreme heat well.

Choose The Right Containers

During periods of extreme heat, the first parts of your garden you should tend to are your containers. Containers dry out quickly and require regular attention when temperatures are high. For those in warmer climates, choosing your containers carefully is one way to mitigate heat stress in container plants.

Dark-colored containers are great for dramatic design but not the most practical in extreme heat. Dark colors are known to absorb and retain heat, meaning that a black or dark blue pot can quickly become a miniature oven for your plant’s root system. This can lead to overheated roots and a dried-out plant, even if you’re meticulous with your watering routine.

Light-colored pots like whites or natural tones do a much better job of reflecting sunlight rather than absorbing it. As a result, these containers stay significantly cooler, ensuring that the soil within doesn’t heat up too much and keeping your plants happier in the long run.

The size of your containers also matters. In small containers, the soil volume is limited, drying out quickly and leaving your plant thirsty and stressed. A larger pot holds more soil which retains moisture longer, giving your plant a buffer against the intense heat.

Material choice is another characteristic to consider. Plastic pots, while lightweight and inexpensive, tend to heat up quickly. Opting for naturally porous clay or ceramic pots allows for better air circulation and can help keep the root zone cooler.

Next time you go pot shopping, remember to consider these factors before planting. Choose light-colored, sizable, and breathable material containers to give your plants a fighting chance during those scorching summer days.

Move Containers

There’s a huge advantage that container plants have over their in-ground counterparts – mobility. One of the easiest ways to protect your container plants from extreme heat is simply moving them to a cooler, shadier location during the hottest parts of the day.

When considering locations to move your containers, look for spots that offer some protection from the afternoon sun, which tends to be the hottest. Areas under large trees or on the east side of buildings are ideal. Another good spot is under a pergola or patio, where the plant will still receive some indirect light.

Make sure you consider the weight and size of your containers before deciding to move them. Large pots can be heavy and frustrating to relocate regularly. You can place them on wheels to make large containers easier to move, but if they are stuck in place, you may need to opt for one of the other protection methods.

DIY Temporary Shade

If a heatwave is bearing down on your garden and your plants are at risk, creating temporary shade is an affordable solution in a pinch. It will give your plants the relief they need from intense sunlight and heat, preventing sunburn and wilting without compromising growth.

Luckily, this usually involves materials you likely already have on hand. A piece of shade cloth or even an old bedsheet and a few poles are all you need to get started.

Start by pushing four poles (old stakes are great for this) into the ground around the plants. Then, attach the corners of the cloth or sheet to each stake’s top, ensuring it’s high enough not to touch the plants. The goal is to filter out the harshest sun, so make sure your cloth is angled correctly so it doesn’t block out the sun completely.

For smaller plants, umbrellas are far easier to use. This way, you can target specific plants that need protection without covering entire beds. Set up patio or beach umbrellas to cast shade over the plants that need it most, blocking out the afternoon sun.

If you have raised beds, creating a raised bed cover is even easier.

Once the extreme heat has passed, gradually expose your plants to their normal light conditions to help them acclimatize.

Install Permanent Shade

Temporary shade isn’t ideal when extreme heat is a consistent issue in your garden. Instead, you can look into installing a permanent shade that allows light in but filters the harshest rays.

Pergolas or shade sails are common options, but there are many solutions to choose from, depending on the layout of your garden and the plants you want to protect. Unfortunately, this is a more significant investment compared to other heat-protection methods. But it provides a lasting solution, reducing your plants’ heat stress year after year.

Pergolas provide dappled shade, allowing just the right amount of sunlight to peek through while protecting plants from the harsh midday sun. On the other hand, shade sails, made from fabric and stretched between points, provide denser shade and can be installed at different angles to block the sun as it moves. You’ll need something like an awning or gazebo for more intense shade.

Because these structures are permanent, you also need to consider the sun’s movement between seasons. The sun’s angle changes throughout the year, so a location that works perfectly in the summer may not offer the same protection in the spring or fall. Hopefully, there won’t be too many instances of extreme heat in these seasons, but it is something to consider.

Permanent structures require some investment and planning, but the benefits they offer in plant protection from extreme heat (and the bonus of a cool spot to relax in, depending on how you place it) can make it a worthwhile project for many gardeners.

Use Plants To Create Shade

Another form of ‘permanent’ structure that can shield your plants from the sun is, excitingly, other plants. Larger plants like trees and shrubs can offer a protective canopy for smaller, delicate plants more susceptible to scorching heat.

As this level of shade is slightly trickier to control, it’s important to understand how larger plants will impact your garden after planting and after they have matured.

Consider the eventual size and shape of your shade-creating plants and how their shade will move throughout the day. Like the other shading methods, this will ensure they’ll cast their shadow where needed most without completely blocking access to the sun and stunting growth.

Choose large-leaved deciduous trees for the highest level of shade if you’ve got the space. Their wide-spreading branches and dense leaves provide a large shadow and relief from the heat. When they lose their leaves in the winter, they also allow the much-needed sunlight to penetrate through.

For a quicker solution, consider fast-growing and tall annuals or perennials. Tall grasses or ornamental plants like sunflowers can provide a fast-growing cover for lower-growing plants and vegetables in a crisis. Climbers can also create a living shade when grown over a pergola or trellis, as long as they can withstand the heat.

This is a great way to add more plants to your garden for diverse functionality. They may take some time to establish but will end up improving the overall look of your backyard at the same time.

Hold Off On Pruning

When the temperatures start to soar, and plants begin to wilt, it’s tempting to grab your shears and start pruning, trimming away all the impacted growth. However, as is the case in times of frost, pruning during extreme temperatures might actually do more harm than good.

Pruning stimulates new growth, producing a hormone that encourages the plant to heal in that spot. While this is usually a good thing, during a heatwave, this puts additional stress on the plant. It’s already struggling to deal with the intense heat, and now it must also allocate precious resources to grow new leaves or branches.

Mature leaves are better adapted to handle hot conditions than new, tender growth. The mature leaves have a fully developed structure designed to protect the plant from sun and heat damage. On the other hand, new growth is more susceptible to sunscald and can use up more water than mature leaves.

The canopy of leaves also provides shade to the lower parts of the plant and the surrounding soil, helping to keep them cool. Pruning may expose previously shaded areas to the harsh sun, leading to sunscald or excessive evaporation from the soil.

Although it’s incredibly difficult when you want to help your plants and improve the overall look of your garden, hold off on any significant pruning until conditions improve. Instead, focus on watering and caring for your plants, ensuring they’re as healthy as possible to withstand the heat wave.

Keep Up With Weeding

Weeding may be a therapeutic activity for some, but it’s a chore for most. I (and my knees and back) tend to agree with the latter. But weeding becomes even more crucial if you’re trying to protect your plants from extreme heat.

Weeds, by definition, aggressively compete with your desired plants for resources, including water, nutrients, and sunlight. In the hot summer months, when water is already scarce, they soak up moisture before your plants can access it, increasing the chances of stress.

Keeping on top of weeds can feel like a never-ending task, especially during the growing season when they seem to pop up overnight. However, a consistent weeding routine can help to keep them under control and keep your plants safe from heat. Aim for a regular, manageable weeding schedule that stops the problem from getting out of hand.

By eliminating these pesky competitors, you can help ensure your plants have ample resources to see them through the heat. Plus, your garden will look tidier too.