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9 Tips for Protecting Plants When It's Hot Outside

Jill enjoys cooking, abstract painting, stewardship & learning about gardening through the MD Master Gardener & Master Naturalist programs.

The Heat Is On!

Make sure your plants survive the summer by protecting them from high temperatures and scorching rays.

Although it's usually a no-no because it encourages fungus, wetting leaves as well as the ground is a good idea when it's super hot outside. Picture: mock orange after a good soaking.

Although it's usually a no-no because it encourages fungus, wetting leaves as well as the ground is a good idea when it's super hot outside. Picture: mock orange after a good soaking.

Slow & Thorough Preemptive Watering

Begin watering your garden slowly and thoroughly days or even a week before hot weather hits.

Water your trees in the morning or, if you don't have time then, late at night, soaking the ground all around the trunk out to the drip line in order to saturate the root zone.

Water slowly & thoroughly.

Applying water to your garden too quickly will result in run-off, & that won't do your plants a bit of good.

Whether you use a sprinkler system, soaker hoses, drip irrigation or water jugs with holes in them, be sure to water your garden slowly so that the soil soaks up the moisture rather than shedding it.

You want to moisten not only the topsoil but also the root zone, that expanse of soil that extends a foot to 18 inches deep beneath the soil surface.

The rosemary plant in the foreground didn't make it during the last hot spell. I simply forgot about it!

The rosemary plant in the foreground didn't make it during the last hot spell. I simply forgot about it!

Check the moisture content of your soil.

How can you tell when you garden needs water?

Different types of soil take up and retain moisture differently. Sandy loam generally drains well, while clay soil holds onto the wet. Most soil, however, is a combination of materials. In other words, your soil probably isn't simply loam or clay or sand.

To make sure that you've watered thoroughly, in a way that will truly benefit your garden, get your hands dirty: stick your fingers down into the ground and check the soil's moisture content before you stop watering.

Another way to tell if your garden needs water? Look carefully at your plants. Are the leaves browned and/or curled? Is there leaf loss? Unfortunately, by the time that sort of damage shows, it may be too late to save some plants.

Last week, when the heat index in our area was at 105 every day, we lost a rosemary plant. By the time I noticed its dull color and curling leaves, no amount of water could save it. RIP R. officinalis!

Water in the morning if you can.

protecting-plants-from-too-much-sun

Slow and thorough watering in the morning is best if you can manage it.

Watering in the morning conserves water. Ordinarily, it's cooler in the morning, and the soil is cool, too, so water won't quickly dissipate through evapotranspiration as it will during the heat of the day.

If temperatures are really up there even in the early hours, you may opt to spray water all over your plants, too, not just on their root zones. Even in a heat wave, however, I tend to avoid wetting the leaves of plants that I know are prone to mildew, including roses, black-eyed Susan and bee balm.

Should you water at night?

If you don't have time in the morning, then very late at night is the second best time to water. At night, I avoid overhead watering completely as the water tends to cling to stems and leaves longer before evaporating, providing the perfect hot, wet environment for fungus and mildew. Instead, I apply all the water to the root zones only.

Should you water in the heat of the day?

In extremely hot drought conditions, you may decide to overhead water again in the heat of the day. Doing so will lower the temperature in your garden and provide moisture for spiders and other beneficial life.


Protect the Soil with Mulch

Evolvulus glomeratus 'Blue Daze" mulched with straw to survive the hot summer.

Evolvulus glomeratus 'Blue Daze" mulched with straw to survive the hot summer.

Water and then apply mulch.

Because it helps soil retain moisture, mulch is one of the best ways to keep plants cool during a heat wave.

Before adding mulch to your bed, water your flowers thoroughly and then apply the appropriate thickness.

Light-colored mulch like straw does double duty, helping hold moisture and cooling the ground by reflecting the sun's rays. For garden vegetables, silver plastic mulch is another option, as are wet weeds.

protecting-plants-from-too-much-sun

Wet Weed Mulch

A master gardener in Calvert County, Maryland, shared her unique method of mulching on the University of Maryland's Extension website: applying wet weeds as mulch. (Warning: don't do this with weeds that are in flower or that are going to seed. You'll end up with a lot more weeds!)

After the thunderstorms that often accompany hot weather, she pulls weeds while they're still wet and piles them around the plants in her garden. The wet weeds add more water to the garden, act as a mulch to hold moisture in and eventually decompose, feeding the soil.

As they say, "It's all good!"

Perform Routine Garden Maintenance

Removing weeds and deadheading should continue even in hot weather. In fact, both are beneficial to your garden and will reduce plant stress.

Weeds not only take up nutrients that your flowers and vegetables could be using, but they also use precious moisture, so pull them up!

The easiest time to do so will most likely be in the morning when the ground is moist with dew.

Removing spent blooms will also reduce plant stress. In fact, hot weather is a good time to make up a morning bouquet of fresh blooms.

Provide Shade for Plants

Turtlehead grows in the only spot in our yard I can keep consistently moist. Beside an open rain barrel, it's shaded by crape myrtle and azalea. Can't wait to its pretty pink blooms in late summer!

Turtlehead grows in the only spot in our yard I can keep consistently moist. Beside an open rain barrel, it's shaded by crape myrtle and azalea. Can't wait to its pretty pink blooms in late summer!

Using covers to provide plants with shade is an option, but I find covers a lot of trouble and not all that effective.

I prefer using other plants to provide shade.

Together, a mix of short and tall plants creates a more moist environment, and ... it seems to work. (Shade is one of the many benefits of the Three Sisters method of planting, a centuries old practice common among Native Americans.)

The hottest days of summer are also a good time to move potted plants into shady locations under trees and shrubs or in your flowerbeds.

Give Non-Native Plants Special Care

Non-native plants probably won't be as equipped to handle the heat in your area as well as native plants. Pictured: a butterfly bush in our side yard that tends to wilt in really hot weather.

Non-native plants probably won't be as equipped to handle the heat in your area as well as native plants. Pictured: a butterfly bush in our side yard that tends to wilt in really hot weather.

Native plants generally have coping strategies that help them survive the particular area in which they are indigenous, so if your area regularly suffers from heat waves, your native plants will survive the hot, dry weather better than exotics.

Plants have various drought-coping traits. Perhaps their pores shut down so that they don't lose water through evapotranspiration (moisture loss through leaves). Or perhaps their leaves are silvery to reflect the sun's rays or fuzzy to provide shade and keep the plant cool.

Non-natives may not be drought tolerant, so you're going to have to provide them with water in order for them to survive a heat wave. As noted above, water the plants slowly and thoroughly so that the topsoil and the root zone are moistened. And check them frequently for signs of stress--curled leaves, burnt stems and leaves, leaf loss and dull leaf color.

Tough Plants Need Love, Too

Plants with tough foliage may not wilt in a heat wave, but that doesn't mean they aren't stressed.

Plants with tough foliage may not wilt in a heat wave, but that doesn't mean they aren't stressed.

Check Drought-Tolerant Plants for Stress

Tough, drought hardy plants may not wilt in a heat wave, but that doesn't mean they aren't suffering.

Check them for signs of stress, too. Are their leaves warm to the touch? Curled up? Have they developed a lackluster color? Warm, dull, curling leaves are all signs of stress.

Give the plants a good, slow drink of water early in the morning. Although you may have chosen drought-tolerant plants specifically so that you would not have to water them, sometimes, when the heat is extremely severe, you simply have to—if you want them all to survive.

Use a Water Delivery System

Drip irrigation is great, but you don't have to have it in order to save plants from the heat.

Drip irrigation is great, but you don't have to have it in order to save plants from the heat.

Drip Irrigation

Drip irrigation is an efficient, water-conserving way to water to plants slowly and thoroughly.

In drip irrigation, plastic tubing is used to deliver water drop by drop to plants' root zones.

Most home gardeners probably don't have a drip irrigation setup for their vegetable plants—or even for their foundation plants—although installing drip irrigation for "permanent" features in the landscape (like shrubs and small trees) is becoming more common.

If you lose plants to drought each year or spend lots of money each year irrigating your plants, drip irrigation could save you money in the long run. It doesn't really cost that much—usually anywhere from 50¢ to a dollar per foot, and that includes all the parts that you need.

Homemade Drip Irrigation (It's not pretty, but it works.)

If even 1¢ per foot sounds like too much to pay for drip irrigation, then check out this essentially cost-free method of slowly delivering water to specific plants.

All you need are empty plastic jugs, something to punch holes with and water.

You'll need large jugs, such as gallon milk or vinegar jugs, about 3-4 of them per small tree or shrub.

You'll need empty plastic jugs. Gallon milk jugs work well.

You'll need empty plastic jugs. Gallon milk jugs work well.

You could also bury jugs with holes in them in your vegetable garden next to plants that require lots of water, like tomatoes.

Some gardeners bury empty jugs, leaving just the tops exposed and filling them with water several times per week in hot weather. Here's how it's done.

  • First, clean the empty jugs thoroughly. Then use an awl or scissors to make a small hole near the bottom of each jug.
  • Fill the jugs with water from your rain barrel, or stick your fingers over the small holes and fill the jugs with a hose.
  • Finally, set the water-filled jugs around the base of thirsty trees or shrubs. The jugs will slowly leak water, delivering moisture to the root zones without causing run-off.

Soaker Hoses

Although soaker hoses can't target specific trees and shrubs like drip irrigation can, they do deliver water slowly, eliminating runoff and providing moisture deep down into the soil. They're ideal for a vegetable garden or flowerbed where plants are ordinarily planted close together.

Made from recycled rubber, soaker hoses have small holes (pores, really) all along their length that slowly weep water.

Can you spot the soaker hose? It's just hard to see thanks to plant life & about an inch of shredded bark mulch.

Can you spot the soaker hose? It's just hard to see thanks to plant life & about an inch of shredded bark mulch.

Downspout, Rain Barrel, Soaker Hose Combination

If you're not capturing at least some of the water that your roof sheds during a rain, you're missing out on a great source of free water for your garden.

My husband and I recently added another rain barrel to our garden. This one we attached to a downspout and a soaker hose, and it's made watering at least one small section of our flowerbeds much easier during the heat waves.

First, we the downspout next to our front flowerbed with a reciprocating saw. Then we attached a downspout adaptor from the shortened drainpipe to the rain barrel.

Funnel water from a downspout into a rain barrel.Attach a soaker hose to the barrel, and snake the hose through your flowerbed.

Funnel water from a downspout into a rain barrel.Attach a soaker hose to the barrel, and snake the hose through your flowerbed.

Next, we attached a soaker hose to the spigot and stretched the hose through the flowerbed.

From past experience, I expect the hose to last four years. (That's about how long the last "permanently" placed soaker hose lasted for us in a bed before it developed rot.)

Before a rain, make sure that the spigot on your barrel is closed so that you'll capture the run-off from your roof. (Excess water will overflow from the barrel at the top.)

Before a rain, make sure that the spigot on your barrel is closed so that you'll capture the run-off from your roof. (Excess water will overflow from the barrel at the top.)

Soaker hoses can be buried in mulch or soil and left in place year round.

Burying soaker hoses is a good idea for several reasons. It will prevent water loss due to evaporation in extremely hot weather.

A buried soaker hose is also more inconspicuous than one that rests on top of the ground, and burying it gets the water closer to where you want it to be (the soil) so there's less likelihood of run-off.

Shasta daisies, Autumn Joy sedum, zinnia, love-in-the-mist, silver mound & marigolds easily mask the soaker hose in our flowerbed.

Shasta daisies, Autumn Joy sedum, zinnia, love-in-the-mist, silver mound & marigolds easily mask the soaker hose in our flowerbed.

Pro Tip Recap

  1. Stay apprised of local weather predictions so you can water thoroughly prior to a heat wave.
  2. Water early in the morning if possible.
  3. Water slowly and thoroughly in order to wet not only the topsoil, but also the root zone, encouraging roots to grow deep.
  4. When applying mulch to conserve moisture, water the ground thoroughly first.
  5. Perform garden maintenance like weeding even when it's hot.
  6. Plant heat sensitive plants in the shade of other plants, and move potted plants into the shade or indoors in the afternoon.
  7. Use a water delivery method that is easy for you to implement and appropriate for your budget.
  8. Give special care to non-native plants.
  9. Also check drought-tolerant plants and trees for stress. When the heat is extreme, they may need water, too.


Why Do Some Plants Wilt after Watering?

Sometimes, plants will wilt on a hot day even if you've watered them.

I notice this phenomena with our Shasta daisies. The problem, I discovered, isn't a lack of water in the soil; it's the plant's inability to take up water as quickly as it needs to in order to replenish moisture lost during evapotranspiration.

When the sun starts going down and the water loss through the leaves begins to lessen, the plant will perk up again.

A clump of Shasta daisies alongside zinnia and hyacinth bean vine one day after a nasty week of over-the-top hot weather. No wilting now, but boy were they wilted earlier!

A clump of Shasta daisies alongside zinnia and hyacinth bean vine one day after a nasty week of over-the-top hot weather. No wilting now, but boy were they wilted earlier!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2013 Jill Spencer

Comments

Jill Spencer (author) from United States on January 16, 2014:

Hi Rebecca! When I saw that I had a comment on this hub, I thought I'd been spammed. LOL. It's so cold outside! In fact, it's starting to snow here. I think you were the hubber who suggested this topic in a comment on another hub, and, as you can see, I finally got around to writing about it. We had a very hot & dry or very hot & wet summer last year with little moderate weather in between, so gardening was a real challenge. Thanks for the comment! All the best, Jill

Rebecca Mealey from Northeastern Georgia, USA on January 13, 2014:

I wanted to read this because I don't have a lot of shade in my yard, so the tips were helpful...even though hot weather seems far, far away! Your photos are spectacular. I enjoyed just looking at them. I love the milk jug idea!

Jeanne Grunert on October 22, 2013:

Good Hub! You always have great gardening advice. Thanks for sharing it, and I loved the photos, too.

Jill Spencer (author) from United States on October 22, 2013:

Hi thumbi7! Thanks for your kind comments. I really appreciate them! A rain barrel is such a savings in so many ways--for the amount of well water we use & on my back! Take care, Jill

JR Krishna from India on October 21, 2013:

The tips for watering the plants are very useful. Using rain barrel to collect water is a brilliant idea.

I loved reading this article

Thanks for sharing

Jill Spencer (author) from United States on October 21, 2013:

Thanks so much, kikalina. I love rain barrels, too. Wish I had two more of them! Take care, Jill

kikalina from Europe on October 21, 2013:

Your hubs are amazing.. The photos fantastic and your rainwater barrel is a great idea. Sharing

Jill Spencer (author) from United States on September 02, 2013:

Hi Thelma! Nice to hear from you! I hope the tips come in handy for you. Take care, Jill

Thelma Alberts from Germany and Philippines on September 01, 2013:

Thanks for the useful information. Great hub and I´ll be pinning this for later use. Have a great week!

Jill Spencer (author) from United States on August 21, 2013:

Our summer's been either really wet (too wet) or hot and too dry. A tough year for tomatoes! Thanks for dropping by, Glimmer Twin Fan. Take care, Jill

Claudia Mitchell on August 21, 2013:

We've had a fairly wet summer, with the exception of the last few weeks. I wish we had drip irrigation, but the way my yard it, it would not look really nice with all of the hoses spread around. Mostly I try to plant perennials that don't need too much water, but my deck things and my few annuals definitely need it. Pinned/shared this really useful hub.

Jill Spencer (author) from United States on August 04, 2013:

Hi Carol! Haven't heard from you in a while. Hope you're doing well. Thanks for commenting. I'm sure it's really, really hot in AZ. Would plastic flowers melt in the heat there? Take care, Jill

carol stanley from Arizona on August 04, 2013:

We have heat but no plants in our yard..You are always a wake up call I should start sprucing up the yard.

Jill Spencer (author) from United States on August 02, 2013:

Hi Patricia! Here we're vacillating between hot, dry stretches and steamy periods of excessive rain. Not the best year for tomatoes! (at least for us.) Nice to hear from you. Have fun this weekend. --Jill

Patricia Scott from North Central Florida on August 01, 2013:

You are so clever, Jill. You are right..the jugs are not pretty but they get the job done. This summer where I live in north central Florida our irrigation has not been a problem...we have had so much rain that my rain containers are full all the time..and I am thankful for that.

You have offered so many helpful suggestions. I am bookmarking for later reference.

Voted up++++ Angels are om the way ps

Jill Spencer (author) from United States on July 27, 2013:

That sounds like paradise, Deb! Have a good weekend. --Jill

Deb Hirt from Stillwater, OK on July 27, 2013:

This is a perfect time to discuss this. The weather is crazy all over the country. It rained again yesterday and topped out at 82!

Jill Spencer (author) from United States on July 26, 2013:

Thanks, Eddy. Always nice to hear from you. Have a great weekend!--Jill

Eiddwen from Wales on July 26, 2013:

Interesting and useful the dirt farmer.

Voted up and here's wishing you a great day.

Eddy.

Jill Spencer (author) from United States on July 25, 2013:

Hi Lee. I've never tried to sterilize the soil but your idea sounds like a good one. I might even try scraping up the infected topsoil first and replacing it. Thanks for commenting!

Hey livingsta! Thanks! Hope the ideas work for your mum.

@ Thelma. I can't say enough good things about rain barrels, although I wouldn't recommend one w/out a cover because of mosquitoes and tadpoles!

@ Sherry. Don't put flowering weeds or weeds that have gone to seed in your beds! Sorry I didn't explain that better. In fact, I usually chop up the weeds that I use as green manure. Thanks for your comment! I'm going to go back and add that to the hub. All the best, Jill

Sherry Hewins from Sierra Foothills, CA on July 25, 2013:

Great tips, but I wonder with the wet weed mulching, doesn't that reseed the soil with weeds for the next year? I've been tempted to do that as I have plenty of weeds available.

Thelma Raker Coffone from Blue Ridge Mountains, USA on July 25, 2013:

As always, a great article and your pics are beautiful. I also am thinking of a rain barrel. It just makes good sense.

livingsta from United Kingdom on July 25, 2013:

Very informative article for gardeners. I have gathered a few tips here which I will be passing on to my mum. Thank you for sharing this with us. Voted up and sharing!

Lee Raynor from Citra Florida on July 25, 2013:

Hey Jill

Good tips here. Your Hubs are always informative. We're having a very wet summer this year (From 1 to 4 inches a week) so I haven't watered in weeks. My freezers are full of veggies and the gardens all look like Hell, weeds have taken over but summer is not gardening season in Florida.

I'm trying to sterilize the soil where I cut down some tomato plants by covering it with clear plastic sheets. Any advice? I read someplace that you can cook the soil that way and kill weeds and pathogens.

Jill Spencer (author) from United States on July 25, 2013:

Hey MsDora! Glad you can use some of these ideas. Here in MD, we're having a bit of a respite from the heat right now, but expect temps to rise again soon. Stay cool! --Jill

Dora Weithers from The Caribbean on July 25, 2013:

I gained lots of new ideas from this article--the water jugs, watering at night etc. Voted Up and Useful. Thank you very much for sharing.

Jill Spencer (author) from United States on July 24, 2013:

Hi purl3agony! You're going to love having a rain barrel. I'd like to have one more. It makes watering so easy, and it comes out at a good temperature, not so cold that it shocks the plants. Thanks for the vote!

Donna Herron from USA on July 24, 2013:

Love this article. We are thinking about getting a rain barrel to put all the rain we are getting to good use :) Thanks for the photos of your rain barrel set up. I appreciate all this information. Voted up!!

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