15 ways to repair heat-stressed plants
On hot days, when many of us retreat indoors to keep cool and comfortable, our garden is likely suffering heat stress and sun burn in silence. It’s often not until we return from work or dash to the mail box that we notice brown tipped leaves and flowers, wilting branches, and a golden crunchy lawn underfoot.
While a good watering will provide temporary relief, there are a few easy and affordable actions you can take that will help your plants and lawn cope better every time temperatures soar.
What to do when hot weather strikes
On hot, dry days, plants lose more water through their leaves and if it isn’t quickly replenished they become dehydrated, wilt and eventually die. So as soon as hot weather starts, soak the soil around your plants and your lawn with a hand-held hose or in-ground watering system early in the morning and/or after the sun goes down.
By watering at these times less water will be lost via evaporation and plants will be better prepared for the next hot day, advises Nursery & Garden Industry Victoria. Another good reason to water early and/or late is that leaves become hot when the sun is overhead and water can scald them. For us humans, it’s also more pleasant to spend time in the garden in the cooler parts of the day.
Watering by hand or using an in-ground watering system gives you better control over the amount and distribution of water, as opposed to the random and lighter spray from sprinklers, explains Greg Seaman of Eartheasy. He also recommends watering young plants, seedlings and seed beds twice a day during extreme hot weather as they have less leaves to create their own shade and smaller, less efficient root systems.
If you have any plants that are extremely heat affected, water them straight away as they might not survive until the evening’s watering session, advises Flower Power’s Jenna Beck. And if you find your small pot plants are heat-stressed with dried out soil, dunk them into a water-filled bucket or sink to soak the soil around the roots. When the soil is wet to the touch on the surface, remove the pot from the water.
Have you noticed water running off the dry top soil and not soaking in? Jenna suggests to temporarily stop watering to give the water time to soften the soil and make it more absorbent, then start watering again in 15 minutes.
Here are 15 ways to repair a scorched garden:
Don’t prune burnt, brown, or dead leaves
Brown, burnt top leaves may look unattractive but they are the first line of defense against the hot sun and scorching, dry winds, sacrificing themselves to provide much-needed shade to the lower newer leaves and branches – the important next generation – and to help keep the soil moist. So, put your clippers down and walk slowly away from the plant. You can do it! When the weather cools in autumn, you can clip it all away.
Strengthen and revive plants with a seaweed tonic
Nutrients rather than fertilisers will help your plants survive the hotter, drier months as the nitrogen in fertilisers can burn a heat stressed plant’s roots and force it to grow rather than repair itself. Flower Power’s Jenna Beck recommends a weekly application of Seasol, a seaweed solution which acts like a multivitamin, providing essential natural compounds and trace elements for resilience and growth, particularly root growth which is vital for water uptake.
Shade young and vulnerable plants
Protect vulnerable and young plants from direct sunlight and dry winds with shade cloths. Choose a high shade factor for young and heat-sensitive plants and a low factor for hardier, older plants. Also, don’t lay the cloths on or too close to your plants to allow good aeration and light, and secure tightly on one side or above the plants depending on your garden’s perspective to provide protection from the harsh midday or afternoon sun. A cost-effective shade cloth option is an old cotton bedsheet, which can be folded to increase its protection factor. In extreme hot weather, spray the shade cloth with water to cool your plants (a popular technique used to cool homes in Australia pre-electricity).
Position pots and planter boxes in the shade
Move your pots and planter boxes to shaded areas of your garden or balcony, or group them together to provide shade for each other during the hotter months. If they require some sunlight, place them where they will receive the early morning or late afternoon sun. Keep pots away from heat reflective surfaces, such as light coloured walls, and large glass windows and doors.
Apply a protective barrier to slow water loss
Spraying your plants with AgroBest’s Envy or Yates Waterwise DroughtShield (previously called Stressguard) adds a coat of biodegradable film that reduces their water loss and protects them from the heat, dry wind and sunburn. Spray both upper and lower leaf surfaces and stems and re-spray any new growth in the cooler part of the day. The film also stretches to accommodate growth and offers protection for up to three months – pretty much the entire summer.
Don’t mow as often (this one’s not hard to follow!)
By cutting your lawn too short you remove the shade that the taller blades provide, which in turn helps retain soil and blade moisture, explains Greg of Eartheasy. Cutting grass too low can also expose the roots to the sun, which increases moisture loss, sun damage, and wear and tear from foot traffic. So how low can you go? We recommend at least 8cm high. As with plants in hot weather, don’t fertilise your lawn as the nitrogen can burn the roots and heat-stressed lawns don’t absorb nutrients as well.
Water deeply and regularly year-round to nurture extensive root systems
Regular, adequate watering loosens the soil to help plants develop deep, extensive root systems, which are essential for surviving hot, dry weather. Be careful not to over-water as this can cause the roots to rot. If you are unsure of how much water to give your plants or tend to forget to water, invest in a drip system as it regularly delivers water slowly and consistently over a long period of time, rather than a deluge all at once.
Fertilise your garden and treat disease and pests
Fertilising and keeping disease and pests at bay in the cooler months will help nurture healthy, robust plants that will better cope during prolonged hot weather, and recover more readily from heat damage and dehydration.
Insulate the soil with mulch
Applying a layer of organic mulch after watering will insulate the soil against the heat and dry air by locking in moisture. With moisture loss reduced you won’t need to water as much and another benefit of mulch – it helps keep weeds at bay!
A light-coloured or reflective mulch that reflects the sun’s rays such as dry grass clippings. You can make your own grass mulch by spreading your clippings over the lawn either as you mow (without a mower catcher) or after on a sunny day to dry out.
Create an underground water storage for your plants
Water-saving granules or crystals provide water as the plant needs it by filtering through the soil surrounding its roots, absorbing water and slowly releasing it when the soil becomes dry. Spread granules or crystals such as Amgrow’s Wettasoil, Hortico Water Storage Crystals, and Richgro Ezi-Wet as per instructions and follow with a good soaking to provide water for them to absorb.
Condition your soil for better water penetration and retention
Soil conditioners improve water penetration and retention which helps plants cope in hot weather. Seasol’s Super Soil Wetter and Conditioner has liquid seaweed and compost that boosts growth and health while Yates’ Waterwise Soil Wetter has an agent that softens clay soils to improve root growth and water movement.
Clever plant location
Plant vulnerable and heat intolerant varieties away from areas exposed to full sunlight and prevailing winds over the hotter months and position young plants, which struggle to survive in hot, dry weather because of their shallow root systems, in the shade of larger plants. Be careful not to choose a densely shaded area as some sunlight is needed to thrive and grow.
Choose heat and drought tolerant plants
Choose plants that cope well in hot, dry conditions such as non-tropical natives such as bottlebrush and acacias (wattle), which have efficient and robust root systems and tough, thin leaves that reduce moisture loss, and succulents and cacti that retain water in their leaves and stems to use when the soil dries out.
Plant before or after hot weather
By planting in spring or autumn you give plants time to grow their root systems which will enable them to cope better when the hot weather arrives.
Prepare root-friendly soil
Soil that facilitates deep water penetration and retains moisture and nutrients is essential for plants to survive and thrive in hot, dry weather. Lighten heavy and dense soils with organic matter and sand to make it easier for roots to grow deep and for water to penetrate properly.
As you can see, with a little extra TLC you can help your garden recover from a hot spell and better prepare it for the next one. Now it’s your turn to head for the shade and enjoy a glass of ice cold water!
Do you have any summer planting tips you’d like to share with our readers?