Too much sunshine can take its toll on container gardens. They’re already at a disadvantage – potted plants tend to get hotter and dry out quicker than those planted in the cool ground.
The results can be scorched leaves, wilt, and even death if the roots get too dry – none of which are ideal for a summer patio display.
However, don’t let hot weather deter you from planting up some pretty pots. By protecting your plants from a heatwave, you can enjoy a thriving container garden that enhances your outdoor living space.
Keep your container garden looking its best all summer long with these easy ideas.
The first step when creating a heat-proof container display is choosing suitable plants. While some will quickly flop, scorch, or shrivel when exposed to soaring temperatures, there is a wide range of tougher, drought-tolerant options.
Coastal plants are often a good bet, as are those suitable for dry gardens. Many silver-leaved plants that hail from hotter climates are also drought-resistant (think lavender and Santolina chamaecyparissus, for instance).
Ornamental grasses and succulents make wonderful drought-tolerant container plants, too. And if you want to add more flowers to the view, there are plenty of beautiful bloomers that can beat the heat – from osteospermum to sunflowers. These ‘Tiger Eye Hybrid’ sunflowers from Burpee are particularly gorgeous, and their compact size makes them a top choice for pots.
‘Opt for containers made of materials that offer insulation, such as ceramic or thick plastic,’ advises Tony O’Neill, a gardening expert of SimplifyGardening.com. ‘This helps regulate soil temperature and reduce the impact of extreme heat on plant roots.’
Larger pots are less prone to drying out, as the greater quantity of soil will help to conserve moisture. Choosing light-colored planters can also help; the paler hue will reflect the heat.
If you’ve already used terracotta pots for your container garden, pay particular attention to the plants inside during sizzling hot days. Although they have a timeless aesthetic, these types of pots are very porous, meaning any water you add will evaporate quickly.
Remember, planting into pots without drainage holes is a common container gardening mistake that’s definitely worth avoiding. Otherwise, the soil can become waterlogged, which can damage the plants’ roots.
Tony recommends shielding your potted plants from direct sunlight during the hottest parts of the day. Consider moving them to a shaded area or positioning them strategically under existing shade sources, such as trees or awnings, he says.
You can also use a shade cloth – ‘a helpful product that is easy to hang over a designated area of a patio or deck,’ suggests Anna Ohler, the Owner of Bright Lane Gardens, a plant nursery in Michigan. ‘The lightweight material dapples the sunlight exposure which can help with temperature regulation,’ she explains. This JIWINNER Sunblock Shade Cloth from Amazon is well-rated and comes in four different sizes. Ensure it’s fixed above the plants, without touching them, to allow for airflow.
Alternative methods to provide afternoon shade include putting bed sheets or other materials over the plants, using stakes or other supports to keep them above the plant canopy, says Dr. Clydette Alsup-Egbers, Associate Professor of Environmental Plant Science at Missouri State University. ‘I’ve even seen gardeners use large umbrellas over their plants when it’s really hot.’
‘I always recommend adding a healthy layer of organic mulch (such as cedar chips) to the surface of the soil on a container plant,’ says Anna. She advises applying it 2-2.5 inches thick – it will help the soil retain moisture by slowing down evaporation rates.
‘This mulch will incidentally also help insulate the plant during the winter months,’ she adds. What’s more, it’s useful in suppressing weeds, and some mulching materials will add nutrients to the soil as they break down.
Keeping your plants happily hydrated can be tricky during the height of a heatwave, but there are some tips and tricks that make it more manageable.
The Royal Horticultural Society recommends adding organic matter to your potting soil, which will improve water retention. However, they warn against adding fertilizer during planting as this can encourage too much lush growth which may be more susceptible to heat damage and reliant on frequent watering.
When it’s time to water your container plants, do so deeply and thoroughly, ensuring the soil is adequately moistened, says Tony. ‘However, avoid overwatering, as it can lead to root rot. Consider using a moisture meter [such as this Gouevn Soil Moisture Meter from Amazon] to monitor soil moisture levels.’
‘If you are growing plants with saucers underneath, be sure to remove any standing water from the saucers,’ says Dr. Clydette Alsup-Egbers. ‘Be aware that plants may need water more than once a day, especially if it’s a larger plant in a smaller container or if the wind is strong,’ she adds.
‘If using a hose, make sure to let any warm or hot water run through the hose before watering the plant,’ says Anna. ‘Cool water can help refresh the roots and will cool the soil.’
Tony also suggests trying self-watering containers or irrigation systems specifically designed for potted plants. ‘These systems can provide consistent moisture to the plants, even during hot and dry conditions,’ he says.
Summer-proofing your containers is essential for keeping your patio looking luscious and full of life. But that may not be the only outdoor area that needs a helping hand during extreme heat.
For instance, there are tips for growing grass in hot and dry weather, too, if you have a lawn. Borders can also benefit from some extra TLC, such as ensuring you water at the right time of day. There are also some gardening mistakes often made in a heatwave that are easily avoided. Bear all of this in mind, and you’ll be able to maintain a beautiful backyard that’s ready for alfresco entertaining in style.
Watering plants during a heatwave is vital to their survival. However, water restrictions are common in some zones and introduced in others during heatwaves, so careful use of water for rehydrating lawns, borders and containers is important.
‘When it’s hot, the best time of day to water plants is early morning or in the evening. Plants in containers should be watered twice a day, as soil dries out much quicker in pots. Bonus points if you use re-use rainwater from a water butt,’ say the experts at The Greenhouse People.
‘Water container plants generously, ideally in the evening, once the sun has moved off the garden, which will allow plenty of time for the water to penetrate into the soil before temperatures rise again the next day,’ says Rachel Crow, Homes &Garden’s gardening expert. ‘Otherwise water them early in the morning. Soak the soil thoroughly and try to avoid getting the foliage too wet. Never water the plants in full sun as the water will just evaporate off and you’ll waste water and your time.
‘Container plants will probably require watering daily – possibly even twice daily – during a heatwave, but take your cue from the plant itself and see if it’s wilting and looking thirsty. Just as you don’t want it parched, you also don’t want to go to the other extreme and overwater it.’
Plants need to be watered generously, so that the water penetrates the root zone. However, The Greenhouse People also urge some caution around overwatering plants, ‘which can cause them to leach nutrients and cut off the supply of oxygen to the roots. Instead, pick up the watering can and provide focussed watering at the base of the plant, so roots can benefit as quickly as possible.’
The advantage of a watering can is that it won’t disturb soil like a strong stream from a hosepipe will. Ensure, whatever you use during watering, that the water doesn’t hit or sit on the plants leaves, which can cause leaf burn.
‘If you use a sprinkler, it is impossible not to wet the leaves when watering the garden, so in that case, water early in the morning so that the foliage will dry early and quickly to minimize disease risk,’ say the experts at Bonnie Plants.
You should avoid leaving plant leaves damp where possible as moisture and heat leaves plants more prone to fungal infections such as powdery mildew. It can be cumbersome to get rid of powdery mildew, so prevention is the best solution.
‘Container plants will be the first to dry out in a heatwave so you need to take extra care to ensure they do not perish in especially hot spells. Move containers into a shady spot where they will be protected from the heat of the midday sun,’ says Rachel Crow.
Plants suffering in borders can be protected from clever garden shade ideas. These could be something as simple as shade cloth (available at Amazon), which can be fixed above plants with stakes to provide protection from the heat of the sun. Shade cloth comes in different grades so that you can choose one to suit the shade needs of the plants below, though between 30 to 50 per cent shade cloths are recommended by experts for most plants.
If hot weather is a persistent problem where you live, you may want to consider more permanent solutions, such as pergola shade ideas, to protect plants long-term.
Companion planting is usually talked about in terms of warding off pests or encouraging pollinators. However, you can use companions as a natural way to create shade to protect plants from heat. The best way to do this is to plant tall heat-tolerant plants around more tender, shade-loving plants. Ask for help at your local garden center to ensure you position plants that enjoy growing together for best results.
‘Most gardeners can appreciate the benefit of mulching. This can hinder weeds, eliminating the need for hard work when you’d rather be sipping a cool drink in the shade, as well as offer nutrient-rich organic matter to provide a lifeline when things get hot,’ say the experts at The Greenhouse People.
Mulching borders and containers will help plants’ roots retain moisture. A layer around 3in deep will stop the heat penetrating the soil and ensure it stays moist.
‘If you lay down this thick layer, the top few inches of soil where most root activity occurs will be kept moist and cool. This will increase your crop yield if you’re a vegetable gardener and reduce the amount of watering needed no matter what you’re growing,’ they continue.
It’s important to choose the right type of mulch for the zone you are in and the plants you are trying to protect, since each will offer a different level of moisture retention, however a simple guide is that light-colored top layer mulches can offer more protection from heat than dark-colored ones.
‘One mulch that will increase water retention is vermiculite (available at Amazon). This can be found in potting soil or purchased by itself. A miracle product for gardeners, vermiculite increases nutrient retention and aerates the soil, resulting in healthier plants,’ conclude The Greenhouse People.
If you are a fan of permaculture gardening, which espouses a more natural approach, you may have a natural layer of mulch from fallen leaves on your borders and containers already. However, in areas where there are wildfires, you will want to cover or replace this with non-flammable mulches, such as pebbles or gravel.
We have already said that container gardening ideas are vulnerable to extreme heat, and while watering and moving them to shade can help, you may find that the containers’ material is constantly losing the battle for you.
Terracotta is the worst culprit: if not sealed, it allows for quick evaporation, meaning plants will dry out much more quickly. Sealing this material with terracotta sealant (available at Amazon) will improve the situation.
Plants left in the black plastic containers you bought them in will suffer too – these will be best protected from heat by repotting into light-colored containers which reflect sunlight (and deflect heat) more effectively.
If your plants need feeding and there’s a heatwave too, it’s important to ensure that you feed them at the right time. Fertilizer should never be added to dry soil which can lead to the plants becoming ‘burnt’. Ensure the soil is kept moist during and after fertilizing to allow the nutrients to be properly absorbed.
To keep your lawn green and thick during a heatwave, it is not necessary to use your entire zipcode’s water supply.
‘A well-established lawn should require minimal watering in increased temperatures. Once a week should be enough and your mowing routine should drop to once a week during periods of drought,’ say The Greenhouse People.
‘Before you mow, check the blades are sharp, to give a clean cut to the grass. When mowing, adjust your blade to a higher setting to ensure grass stems provide maximum shade to the soil. Afterwards, leave the cuttings instead of raking to provide shade and to avoid damaging your lawn.’
Just because there’s a heatwave that doesn’t mean you don’t want to improve your backyard’s looks with new plants. However, putting them in at the right time of day is vital to them doing as well as possible.
‘If you add new plants to your garden in the summer, plant on a cloudy day and water well if the weather is warm. Increase the plant’s chances of surviving the heat by using half mulch half potting mix,’ say The Greenhouse People.
And if you’re going to put in new plants, ensure you are thinking drought-tolerant planting ideas.
‘You might want to consider drought-resistant plants alongside more heat-sensitive varieties to keep your garden looking healthy,’ say The Greenhouse People. ‘Herb garden ideas such as rosemary, marjoram and lavender love the heat and their flavor becomes more intense in the hot summer months.’
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