Heatwaves in summer are of course an increasingly common occurrence in many areas. So creating gardens that are able to withstand those conditions is an important consideration for many gardeners. In this article, you will learn how to protect plants from summer heat in your garden in the UK.
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Planning Ahead for Heatwaves in Summer
It is always important to plan ahead in your garden so that you can learn how to protect plants from summer heat, as well as be able to create a space that can truly meet our needs in a sustainable way, not only for a single summer but for many years to come.
It is unfortunately inevitable that our climate will continue to warm over the decades to come, and we need to be prepared in our gardens, as we do in a broader sense in our lives. We need to be able to both mitigate and adapt to Anthropocene climate change.
Part of being prepared means planning ahead for heatwaves in summer that we know we should expect to experience on a more frequent basis over the decades to come.
But what exactly does it mean to be prepared? What exactly can we do as garden designers and gardeners to plan ahead for heatwaves in summer, and know how to protect plants from summer heat?
Choosing the Right Plants for the Right Places
Firstly and most importantly, planning ahead and creating gardens that can survive heatwaves in summer means looking very carefully at the plants that we choose. We always need to think carefully about plant choices to find the right plants for the right places and the right purposes.
Heat Tolerant Plants
When we are planning a garden and choosing plants in the UK, we often tend to focus on plant hardiness in winter – thinking about the minimum temperatures that plants can cope with other the winter months.
But it is important to remember that has well as having minimum temperature requirements, plants can also only cope with temperatures that rise to a specific maximum too. So increasingly, to make sure that plants can cope with soaring temperatures during heatwaves, we need to look at heat-hardiness too.
Thinking about heat tolerance is especially important if you are a polytunnel grower. Since, of course, the temperatures in a polytunnel can and frequently will rise much higher than they do in the rest of your garden – making things easier for much of the year but also potentially making them more challenging during heatwaves.
It is important to understand that some plants can cope more easily with extreme heat than others. And to plan for the worst extremes that we might experience in our gardens over the years to come.
Drought Tolerant Plants
As well as thinking about the heat that plants can cope with, we should also consider drought-tolerance. Of course, during heat waves, water can often be in short supply, and of course water will evaporate more quickly from the soil or growing medium of garden areas and plants will transpire more as temperatures rise.
Plants that are better able to cope with the stresses involved not only in higher temperatures but also with low-water availability will often fare best during heatwaves and be able to withstand extreme conditions.
Understanding the Impact of Heat on Plants
It is important, in order to be able to choose the right plants, to understand the mechanisms within plants, and how heat impacts those plants.
Excessive heat can stress plants by causing water loss through transpiration, leading to wilting, stunted growth, and even death. It can also increase the risk of sunburn and the scorching of leaves and damage plants physiologically.
Creating Shade and Shelter for Plants with Plants
Choosing the right plants for the right places is also important for learning how to protect plants from summer heat. This means not only thinking about the yields we can obtain and what we want to achieve, and of course how well plants will do in a given setting. It also involves thinking holistically, about how plants in your garden will work together.
It is important to remember, when designing your garden, the role that plants can play in creating shade, shelter and more optimal conditions for other plants growing close by.
Trees, shrubs, and taller herbaceous plants can be used to create more sheltered and cooler microclimates to support other plants that are not necessarily as well-adapted to the heat.
Careful consideration of sunlight and shade can help you to work out the right planting plan for your garden space. You can select plants carefully and combine them cleverly so that you optimise temperatures in the shoulder seasons and winter, while keeping things cool through the height of summer.
Protecting plants from a heatwave does not always involve man-made structures. Plants can often be the first line of defence for other plants, and can help you create shade and shelter for human use of the garden during extreme heat.
Utilising Protective Covers, Garden Structures and Windbreaks
While it can often be helpful to think first about how to use plants to provide protection for other plants during summer heatwaves, you might also consider adding other protective features.
Shade cover polytunnels, or other shade covers, for example, can be used to create an environment more conducive to growing certain crops in summer. Within or below such a structure there will be less worry over the survival of garden plants during heatwaves. The temperatures of both air and soil can be cooler inside, and water loss will be reduced.
Other garden structures such as pergolas, or gazebos might also be used to create beneficial shade in a garden, to help create cooler and damper areas where a wider range of plants can survive and thrive during summer heatwaves.
Natural windbreaks of trees and shrubs might also be enhanced with clever fencing etc. which can help to prevent wind-drying from worsening moisture loss during hot weather.
Maximising Soil Moisture and Reducing Evaporation
One important thing to understand about heatwaves is that plants can be stressed by both the air temperature and, crucially, the temperatures of the soil. Soil health is of course crucial to plant health at all times, and so taking care of the soil is of paramount importance.
There are several steps that we can take to ensure that the soil has the health and resilience it needs and that we keep it moist and cool during heatwaves in summer.
One crucial thing that we can do is ensure that the soil contains plenty of organic matter. Higher organic matter content makes for a healthier soil, which can retain water more effectively without becoming waterlogged or overly saturated.
Covering the soil with a mulch of organic matter helps to retain soil moisture, as well as adding nutrients and suppressing weeds to a degree. Mulches also help to keep the soil cool by reducing the area of soil that remains bare.
Bare soil should be kept to a minimum and we should ideally try to keep living roots in the soil over as much of the year as possible. Vegetative cover reduces soil temperatures and helps to keep plant roots and soil micro-organisms safe during heatwaves in summer.
Avoiding Common Mistakes in a Heatwave
Of course, planning and preparing, careful design and creation of a heatwave-proof garden are more important. But how you maintain a garden during a heatwave in summer can be important too.
During heatwaves, there are a number of common mistakes that people can make.
For example, people will often make the mistake of watering little and often during hot weather. But this approach can cause shallower roots and make plants less able to withstand hot, dry weather in future.
You will typically have to water more often in hot weather, but each time you water, you should make sure that you water deeply and well. This will encourage deeper root growth.
Additional Tips for Heatwave Gardening
When gardening and maintaining a garden during a heatwave, it is important to make sure you have suitable watering or irrigation systems in place. It is a very good idea to make sure you have set up sustainable and water-wise irrigation systems for all your growing spaces.
Having sustainable water systems in place will make it easier for you to maintain your garden even during heatwaves. Using rainwater you have harvested earlier in the year can safeguard your garden during potential hosepipe bans.
You should make sure you choose irrigation options that keep freshwater use to a minimum, and that you have also taken steps like shade creation and mulching to reduce water use.
You should also have made sure that you have taken steps to keep a polytunnel growing area as cool as possible during summer heatwaves. And done all you can to protect other important areas of your garden.
Check out more tips on how to deal with a heatwave in your polytunnel garden.
Natural History Museum. (n.d.). What is the Anthropocene? [online] Retrieved from: https://www.nhm.ac.uk/discover/what-is-the-anthropocene.html [accessed 27/07/23]
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.