Heat Wave Gardening Advice – Learn About Plant Care During A Heat Wave

Heat Wave Gardening Advice – Learn About Plant Care During A Heat Wave

By: Amy Grant

The time to prepare for plant care during a heat wave is well before it hits. That said, in this day and age of uncertain weather, even areas that are not known for high temps can get hit with a sudden heat wave and gardeners may find themselves gardening in a heat wave. Special care is needed for plants during a heat wave and there are, indeed, recommendations for heat wave gardening.

Heat Wave Gardening

A handy tool to help navigate heat wave gardening is from the American Horticultural Society. They have created a Heat Zone Map containing 12 zones across the United States. Each zone indicates the average number of days each year that a heat event occurs – when temperatures exceed 86 F. (30 C.), the temperature when plants begin to suffer from heat.

Planning a garden specific to your climate is the best way to combat gardening in a heat wave. While the map will indicate if you should be planting heat tolerant cultivars, it isn’t a cure all, especially if you have tender annuals growing. So how do you go about caring for plants in a heat wave?

Start with healthy plants. Healthy plants are more able to tolerate heat than those stressed by lack of irrigation and nutrients or weakened by disease and pests. Plant in soil that is well-draining, rich in organic nutrients, and easy to keep irrigated. Also, plant at the correct depth; roots that are too close to the surface will fry during a heat wave.

Caring for Plants in a Heat Wave

Even when your plants are in the best condition they can possibly be in, they still need specialized plant care during a heat wave. Be sure they are watered (water early in the morning), mulch around the roots to keep them cool and help retain moisture, and provide shade. Shade can be in the form of a shade cloth, old sheet, or even a beach umbrella.

Despite your best efforts of caring for plants in a heat wave, some will inevitably fail. Cool weather crops will bolt, for instance. Sometimes, you have to cut your losses and just replant with heat tolerant veggies like beans, chard, or carrots.

Plants grown in containers need extra special attention. Container grown plants tend to dry out more quickly than those in the garden so extra attention to watering is vital. Mulching around the roots will also help to keep them cool. Also, if possible, move the container into a shaded or semi-shaded area. If lacking that option, consider providing shade with a shade cloth or the like.

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Master Gardener: How to help protect plants from extreme heat

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Q: In the last few years, we have had early and sudden heat waves in Southern California. Is there any way to protect my plants from the extreme heat?

A: Extreme heat waves are particularly devastating early in the summer, when plants have not had a chance to acclimate. Although you may not be able to prevent all heat damage, there are a few steps you can take to minimize it.

Irrigate deeply and less frequently to encourage deep root growth. When an extreme heat wave is forecast, ensure that your garden is well-irrigated but not over-watered. The soil should be moist, but not muddy. Morning or early evening is the best time to water. Irrigating during the hottest part of the day results in water loss due to evaporation.

Mulch deeply to retain soil moisture and protect surface roots. Between 3 and 8 inches of organic mulch, such as natural bark chips, straw, or compost, is ideal. Dried grass clippings work especially well around young vegetable plants.

Shade cloth is useful protection against intense sun, but it should not touch the plants. Set up a support structure so that the cloth is at least a few inches above the top leaves.

When mowing your lawn, set the mower blade to the highest position. Keeping your grass longer helps to shade the ground, which keeps the soil moist longer and shades out sprouting weeds.

Finally, choose heat-tolerant plants. Succulents and natives are usually a safe bet. Plants that have small, thick leaves, and/or gray foliage are often well-adapted to hot climates.

The best time to water your plants during a heat wave

Friday, July 6, 2018, 10:10 AM - When the warmer weather strikes, our gardens and outdoor spaces become a perfect oasis for rest and relaxation. But as nice as the hot weather might be, extreme conditions and record-breaking temperatures can wreak havoc on your plants.

There’s of course no question, that when it’s hot, plants will need watering, but knowing when’s the best time to do this can be tricky. Evening watering gives plenty of time for the water to penetrate the soil and for the plant to take it up, but there is a concern that leaves staying damp overnight will provide access to disease.

On the other hand, morning watering means leaves will dry out faster – but there is less opportunity for the water to penetrate the soil and for plants to take it up before the day gets hot. So what’s the answer?

All living things need water to allow chemical reactions in their cells that provide energy for growth. Plants also need water to carry nutrients from the soil to the growing cells. This water is drawn up to replace water lost through stomata – the breathing holes in leaves. These stomata are needed for gas exchange – carbon dioxide in, oxygen out – during photosynthesis. In high light levels, on sunny days, a lot of carbon dioxide is fixed to make sugars by photosynthesis. Loss of water is also important to cool plants on hot days.

If plants run short of water they shut down their stomata and photosynthesis stops and is replaced by photorespiration – a process that releases carbon dioxide. Desert plants get around this by breathing at night and storing carbon dioxide for release to photosynthesis during the day while the stomata are shut. But in our gardens, few plants are adapted to do that.

As the water shortage gets more severe plants will wilt – the beginning of cell collapse. Initially this is temporary wilting and the plant can recover rapidly when water is available. But further drying will cause permanent wilting, which results in the death of parts of the plant – or even all of it. Some plants survive drought by dying down below ground – this is the case with garden bulbs such as bluebells, daffodils, tulips and snowdrops. Others may shed their leaves or survive only as seeds.



What is generally agreed is that plants should not be watered while in full sun. The notion that wet leaves on sunny days cause scorch in plants was disproved nearly ten years ago. But there is no doubt that watering in full sun is not water efficient – as much of it will evaporate before entering the soil.

In the current hot breezy weather it is probably best to water in the early evening. This gives the plants enough time to dry out, but there is still the chance for overnight water uptake by the roots. And if you want to water in the morning then start very early – before the sun is shining.

When you water, the key thing is to ensure all layers of the soil in the root zone are wet. Regular light watering causes shallow rooting of plants and makes them less drought tolerant. So water plants thoroughly but occasionally – and don’t let the soil completely dry out because it becomes harder to wet at that stage.

You can water the soil rather than the plant, but take care not to cause the soil surface to form a hard pan. A bit of mulch (wood chips or compost) can protect the soil and keep moisture in – but beware of slugs.


Plants can have too much of a good thing – and while the surface might be dry, the soil 15-20cm down, might not be. Most plants will have a greater root depth so could well be pulling up water that you can’t see.

The best rule of thumb is if the plant is not wilting it probably has access to water. Some herbaceous plants will wilt in full sun to save moisture but will then rehydrate as the temperature cools later in the day (temporary wilting). My garden lupins are doing this on a daily cycle at present, but they are deep rooted and they do pick up in the evening.

You must keep containerised plants well watered. Water on to the soil and water in the evening. As with any other watering, water thoroughly and then not again until there is sign of need. Greenhouse tomatoes will probably need watering daily at present. And if you are growing carrots make sure the soil stays moist or you may end up with split roots.

Your lawn will probably be looking quite dry, but don’t worry too much about this – as grasses die back when dry but can regrow quite quickly when the rains return. One things to remember though, is to avoid excessive walking on a brown lawn or you will end up with bald patches – this is because the combination of drought and heavy wear are just too much for your lawn to handle.

So the message is clear, enjoy your garden in the heat, but remember that your plants are similar to us humans – they too enjoy a bit of shade and a nice drink.

This article was originally published on The Conversation. Read the original article.

2. Water your garden and shrubs early in the morning.

A heat wave can dry surface soil quickly, which dehydrates shallow roots. Water is also lost through leaves in hot weather, so your plants will need a thorough watering. This should be done early in the morning, especially if you use a sprinkler to water, since most water from a sprinkler is lost to wind and evaporation during the hot times of the day.

Watering in the morning also prevents heat scald, which can damage leaves that are watered while the sun is directly overhead. In extreme hot weather, seed and nursery beds may need a second watering later in the day–along with smaller raised beds and containers.

During a heat wave, the need for water conservation is heightened. Hand watering has the advantage of delivering just the right amount of water for each crop. It is also a more efficient method of watering compared to sprinklers, since only the targeted crops are watered.

Soaker hoses are ideal since they can be used anytime during the day, because plant leaves are not wetted. Soaker hoses can be placed beneath the mulch to access the soil directly while hidden from view.

Watering in the morning is also a great defence against slugs, since conditions are drier overnight. Fungal diseases are also discouraged. It’s also more pleasant for you to water in the early morning while it’s still cool in the garden.

The best kids' garden furniture to buy, including mud kitchens, playhouses and sun loungers

Mud kitchens have been all the rage recently, thanks to their guaranteed garden fun. This classic style from Amazon features an oven with door, a removable splash tub, a starter set of stainless steel pans and a mixing whisk. We're certain kids will love this.

Let your little ones relax in style with this adorable mini chaise lounger. We love the mini cup holders, perfect for a refreshing drink in the garden.

Designed to enhance playtime, this deluxe picnic table has two green containers for sandpit or water. They are also easy to remove, too, meaning that you can use it as a classic table afterwards.

What an adorable mini bistro set! With a heavy-duty steel frame, it provides a safe space for your little ones to relax in the sunshine. The umbrella provides a shield from the sun, while the folding chairs can be easily stored away after use.

This affordable swing chair will go down a treat with children. Made from pine wood, it's a brilliant buy for just £17.99. Simply hang and secure from the branch of a tree and enjoy.

If you're after a kids garden furniture set, then look no further: this stylish wooden table with bench is perfect eating, doing crafts and playing table game. It's tilt-proof, has been tested for harmful substances and has no clamp points.

If you're looking for a fancier mud pie kitchen then add this one to your wish list. With a little window, shelves and space for cooking, it lets children get hands-on in the garden.

Give your children a reason to head outside with this fun-packed outdoor playhouse. With a built-in kitchenette, kids can serve up fun play food to their friends at the attached picnic table.

In bright blue, this picnic table is brilliant if you're looking for a practical wipe-clean option. Seating up to four children comfortably, it folds flat for easy storage and transportation.

Looking for an investment piece? Treat your little ones to this wooden playhouse, which has a small door, two little windows and door handles so children can play safely.

Let your little ones dine alfresco this summer with this sweet table and chair set. Choose from pink and blue.

This wooden shop playhouse — made from smooth fir wood — is sure to inspire imagination. It comes with a chalkboard, windows and is also easy to slot together.

Match your kids' furniture to your very own with this adorable companion seat. It has been made from Scandinavian redwood and is perfect for children to sit and enjoy a snack.

This fun lookout tower has its own slide, ball pit, ladder, chalkboard and binoculars to inspire play. We're certain this will guarantee hours of fun!

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Help Your Lawn and Garden Through a Heat Wave

July 29, 2010 / 5:38 AM / CBS

It can be tough to keep your lawn green and your garden blooming in this kind of heat.

But master gardener William Moss has help. On "The Early Show," he shared how you can save your green spaces:

Get Your Lawn and Garden Through a Heat Wave

Summer is barely at the midway point and the heat has been stifling for man and plant alike. Many gardens and lawns have wilted and shriveled. But even for those unfortunate gardeners, there is still time to have beautiful summer landscapes with the right plants and techniques.

Drought tolerant plants make summer gardening easier, even in your lawn. Most lawns are a mixture of grasses, including Kentucky bluegrass. That's a cool-season grass that requires one to two inches of water a week and regular fertilization to keep a green lush look. Of course, all that watering and fertilizing means you'll be doing a lot of mowing to maintain a neat turf. But there are a couple alternatives for the laid-back gardener.

The first is to let your lawn go dormant. Rather than fight against nature, let cool-season grasses do what they naturally do and fade away in the summer heat. The lawn will look brown and dead, but it will only be brown and resting. As soon as cooler temps and rainfall return in September the lawn will green up again. The second option is to plant a lawn of buffalo grass. Buffalo grass is a native warm-season grass that is naturally green and growing in the hot summer months. It can thrive on a third of the water and fertilizer of Kentucky bluegrass. In fact many people do not water their buffalo grass lawns at all. It's great for communities with summer water restrictions that still want green lawns.

The downside of a warm-season grass lawn is that during the cooler months it goes dormant. Having dormant lawns in the summer or winter is simply not an option for many people. So most of us grow cool season lawns that require extra watering, fertilizing, and mowing when it gets hot. That's just the burden of a year-round green turf.

Fortunately, the landscape is a little easier than the lawn to keep beautiful through the heat. Plant selection is the key (check Some Like It Hot). There are plenty of drought tolerant shrubs, perennials, and annuals on the market. Native prairie plants are accustomed to summer heat. Mediterranean herbs, like thyme and marjoram, also thrive in hot, dry conditions.

The veggie garden is a little different. All crops will require regular watering to produce well. If your veggie garden has already been toasted by the heat, all hope is not lost. You still have time to plant beans this year and get a crop. For hot dry weather select cowpeas, black-eyed peas, yard-long beans, and tepary beans. These tough plants will fruit with more heat and less water than most other crops.

But unless you have well-established, drought tolerant plants you are going to have to water regularly and during a heat wave proper irrigation of your lawn and garden is crucial. Below are some tips for more info check out Summer Watering.

1. Lawns and gardens need about two inches per week during the height of summer.
2. Water early (near dawn) to reduce water loss through evaporation.
3. Water thoroughly and deeply. Soak the ground to a depth of six inches.
4. Don't water lawns and landscapes every day. If you water deeply and thoroughly, you won't have to. Allow the top few inches of soil to dry out between waterings.
Containers (especially hanging baskets and window boxes) are the exception and may require daily soakings.

Of course, there are a few horticultural tips and techniques can help landscapes and containers beat the heat. Apply a 2" layer of mulch around plants to help the soil stay moist. Compost makes excellent mulch and also improves the soil. Remove weeds as soon as you have a chance. Weeds take water and nutrients away from your plants. Reduce fertilizer use during a heat wave. Fertilized plants require more water than normal. Unless you plan to water more frequently, cut back on the fertilizer.

Finally, for vacation watering the best thing is to have a good neighbor or friend. Next best is to use timers with soaker hoses and/or sprinklers. And don't forget to do a rain dance!

Remember that heat waves are temporary. Keep your gardens healthy through the heat and they'll reward you with colorful flowers and bountiful crops.

For more information on how to help your garden beat the heat, visit William Moss' website here.

First published on July 29, 2010 / 5:38 AM

© 2010 CBS. All rights reserved.

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