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Summer Proof the Garden

The doldrums have arrived. Gardening is at a minimum. I prefer to be inside, reading my newest garden magazine. Outside, plants may be loosing their vigor with bright green leaves fading to pale blueish gray, leaf edges crinkled, leaves dropping — all signs of heat stress. Meanwhile, bugs select the weakened plants for midsummer's wildest party, sucking and munching and having an orgy with all their friends and relatives. What's a gardener to do?heat stressed leaves

Don't let the doldrums get you down! Here are ten things one can do to summer proof the garden:

1. Choose the right plants. Many ornamental plants now have heat zone recommendations as well as hardiness zones listed on their tags. Developed by the American Horticultural Society in the late 1990s, the heat zone map identifies 12 heat zones in the US. These heat zones are based upon how many days a year the temperature rises above 86 degrees, the temperature when plant cells begin to deteriorate. I am in heat zone 8, which means there are 91-120 days when temperatures rise above 86. Look to see if a tag has two ratings for a given plant, such as 3-7/4-6. The first set of numbers indicates the plant is winter hardy in hardiness zones 3-7, and the second set of numbers indicates the plant will survive summers in heat zones 4 through 6. Remember the hardiness and heat zone maps are two different maps, so one needs to know both zones for one's location. I am on the edge of hardiness zones 7b/8a, but I am firmly in the middle of heat zone 8. There are plenty of plants that can take my winters but not my summers! Replace plants that die with others that are more likely to survive. Native plants are usually reliable, because they are well adapted to both winter and summer conditions.

2. Another thing that you can do to summer proof your plants is to add compost to the soil. This improves soil texture, creating large pores for water movement and air infiltration. Roots can also spread more easily, allowing the plant to reach nutrients and moisture. One trick to help retain moisture in sandy soil is to add clay based kitty litter.

3. Add a 3-4 inch layer of good organic mulch around the plant, but avoid piling the mulch directly against the base of the plant. I use a lot of pine straw, which complements my naturally acid soil. Avoid artificial mulches or gravel, which will radiate heat around the plant and is more suitable for desert type plants. 

4. Mow lawns high. This allows more leaf surface for photosynthesis, the process by which plants turn sunlight into energy. Do not fertilize lawns, except with a weak water based solution or with a top dressing of compost. 

5. Water deeply, less often. Frequent shallow watering encourages shallow root growth. Early morning watering is best. Drip irrigation systems winding their way through the plants are ideal. Bury them under the layer of mulch.

6. Group plants according to their water needs.

7. Windbreaks can protect plants against harsh summer winds. Trees, hedges, and fencing are options. Fences should allow air movement through the structure. Solid fences can create heat traps. 

8. I like to mix up a summer tonic for my garden. This consist of 2 tbs. of Epsom salts per gallon of water. To this I add fish emulsion or a seaweed fertilizer, prepared according to directions. The Epsom salts provide magnesium and sulfur, which promote photosynthesis. Fish emulsion and seaweed fertilizer supply many trace elements, amino acids, and enzymes that promote plant health and stress tolerance. I apply this to the soil around just about everything in my garden, especially those plants showing heat stress.

9. Provide shade during the hottest part of the day. You can make temporary shades out of shade cloth or other materials. I have seen colorful umbrellas propped here and there in a garden, giving relief to hydrangeas and other heat stressed plants.

10. Move plants in pots to more protected locations.This recent view of my lawn and garden shows that, so far at least, my garden is coming through this year's summer without too much heat stress.It may be tempting to ignore the garden when the summer doldrums strike. There have been years I wanted to give up and let the weeds have it. Don't! Early morning or late afternoon strolls give you an opportunity to check out plants when the temperatures are a bit cooler, and that is also is the best time to get garden chores done. And if you have summer proofed your garden, you and your plants can stay happy, even when the heat and humidity soars.


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Reader Comments (18)

Great post. We've had blessed relief from some of summer's worst heat because of almost daily rain showers all month. I never thought about giving my plants an umbrella but I have shaded new transplants with an upside down wire trashbasket.

I spent much of Spring trying to decide about planting windbreaks to the north to counter winter's chilling winds. Still have not decided.

Think I'll give my heirloom tomatoes some Epsom Salts and fish emulsion tomorrow and see if they can make it a while longer before succumbing to soil rootknot nematodes.

July 28, 2013 | Unregistered CommenterNell Jean

Great post! I wrote a similar short article for my local city magazine. Seems some gardening stages are universal. Although, suddenly we're experiencing a strange cold snap here in the Midwest. I am not happy about this--makes me want to move south!

July 28, 2013 | Unregistered CommenterPlantPostings

Great post Debs! A really handy guide and collection of advice to make the most and minimise damage on such a dry and warm season there. Such intense length of summer warmth is unlikely to happen here but understand in zones that experience summer similar to yours this post will come in handy.

July 29, 2013 | Unregistered CommenterMark and Gaz

Great advice, and I was interested to read about the heat zone maps. You certainly have to contend with high heat in your garden, for days on end! For us up here in New England, we tend to get one-off situations where we get record high temperatures for a week, then all goes back to "normal". The plants aren't exposed to high temperatures for very long at all, but that single blast of 6 days or so is a real stress test for plants used to more moderate conditions all summer. It's a challenge!

July 29, 2013 | Unregistered CommenterLaurrie

Great hints Deb! I have definitely hit the doldroms. It had been very hot here for about 2 1/2 weeks with no rain and I just couldn't muster up the energy to go out. Now there's a pleasant cool snap and we've had rain so a perfect time for weeding!! Thanks for all the tips. Plus I think I'll pick up a gardening magazine this week - good idea!

July 29, 2013 | Unregistered CommenterAstrid

Excellent and informative post! And my husband will apprecaite the part about cutting grass high. He bemoans the neighbors (and our two Dad's) who, he says, skin the yard down to a layer of dirt and destroy their grass. A friend used to call him Grass Man. And thank you for the Epsom Salt/fish emulsion recipe. Great thing to know!!!! I am headed out to stake my sunflowers per his instructions today lest they fall over and break when they bloom. We created a sunny strip beside a creek as I was running out of sunny spots so I got my seeds in the ground late!

July 29, 2013 | Unregistered CommenterJody Raines

Perfect advice. Everytime I see any of my plants stressed, I feel guilty! I am trying to reduce the number of plants that need irrigation and add more that are heat tolerant; notice the tolerant not that they love it, very few plants except cactus actually love the heat especially if there are drought conditions.

July 29, 2013 | Unregistered CommenterChristina

Good advice for us all. At the moment our heat wave has finished, thank goodness, and the welcome rain has arrived, making the garden look so much happier. Plants are not stressed any more, some have been cut back, these will hopefully sprout again and flower later in the year.

July 29, 2013 | Unregistered Commenterpauline

All excellent suggestions. Oddly as we got to the height of summer the weather suddenly got rather cool, so things are looking pretty good. It is fairly dry, though.

July 29, 2013 | Unregistered Commenterjason

Deb I'm glad you are not letting the heat get you down, good advice and I like that they have recognised that hardiness zoning is not the only zoning needed, I could use one that says how warm/hot a plant needs it to be to grow, my hardiness zone is higher than yours as it's 9 because we don't get cold winters, the sea keeps us warm but a summer high barely reaches 18C/65F much lower than you, I've been kept out of my garden because of the bugs that want to party on me! I agree with planting natives too, you can also find plants from other countries with similar conditions to yours, which gives a bit more variety, keep cool, Frances

July 29, 2013 | Unregistered CommenterIsland Threads

Wonderful advice here, Deb!

I've learned the hard way that, the south, heat kills more plants than cold. Like yours, my garden is entering its summer doldrums. Everything is looking tired and ratty. Come to think of it, so am I! So I'm going to try to give the garden a new burst of energy and get some epsom salts, as you recommended.

Sound advice! Especially about protecting plants from wind. We have had an exceptionally dry summer (for us) and the water loss due to the drying effect of the wind has been striking. Our summer ended about an hour ago, when the rain finally came. At least we got a glimpse of what the summer doldrums are like.

July 30, 2013 | Unregistered CommenterThe Gardening Shoe

Such great advice, and I am taking the cat litter hint to heart...under the fir trees it's nasty, no water, no way. This is only my second summer, so there is so much soil amending to do..and it's now to hot to do anything but watch the compost perculate.


Great idea with the epsom salts...I wish I could tackle the weeds but work prevents me from getting out in the morning and by the time I get home it is too hot and humid....

July 31, 2013 | Unregistered CommenterDonna@Gardens Eye View

Great tips. I've never applied artificial fertilisers to my garden, but a tonic sounds like just what my garden needs.

August 2, 2013 | Unregistered Commenterb-a-g

I love the idea of a summer tonic! One for me and one for the plants...jeannine

August 3, 2013 | Unregistered CommenterJeannine

such a beautiful garden you have, light and airy.

August 5, 2013 | Unregistered CommenterDiana Studer
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