Summer Heat Tips for Your Garden

How does your garden grow?

Does it feel like the only thing thriving in your garden during this heat is the Creeping Charlie?  Heat waves, especially this early and without much rain, can wreak havoc on a garden.  All spring I was hoping for the rain to stop so I could work on a concrete project.  Now that the concrete is in and I am beginning the planting process, all I do is pray for rain.  Here are a few pointers on how you can survive the heat waves and benefit your gardens:

Vegetable Garden

Do Not Over Fertilize. Many new vegetable gardeners may get the idea that really slapping on the fertilizer will help the plant grow even more. And the more fertilizer you use, the bigger and better the plant will get.  When it comes to fertilizer more is not better. Fertilizers should be used when there is a nutrient deficiency in the soil. Plants are going to only take up nutrients as they need them, and any others that are added to the soil will only go to waste. This is especially true when it comes to nitrogen.

Give your plants some shade. Giving your garden some partial shade during periods of extreme heat can reduce temperatures by 10 degrees F or more. You can cover your garden with shade cloth, a snow-fence, or latticework supported on a frame – even old sheets or sheer curtains. Make sure your shade-producing materials are well-secured against high winds, and are high enough above the plants so that your garden will get good ventilation.

These extremes won’t kill the plants, but they will destroy the current crop of pollen on the flowers. Let’s say it’s a searing 97° F. every day for a solid week; no flowers that open during that stretch will produce tomatoes. But, existing tomatoes should be fine, and new flowers that open under normal temps should produce normal pollen and normal tomatoes.


Here are a few ways to prevent excess stress which can often lead to an increase in weeds and bug problems because your lawn is already suffering.

Mow later in the day.  When the weather heats up, the tendency is to wake up first thing and mow the lawn. However, if the grass has morning dew or was just watered, hold off. Wet grass is more likely to suffer uneven cuts. In addition, the clippings get trapped in the lawnmower and are likely to stick together and cover the grass, shielding necessary sunlight. Also, disease spreads easier and grass is more likely to tear from the ground when it is wet.

Cut the lawn different lengths throughout the year. During the summer, the lawn needs a little more shade, so let the blades grow just a little bit more. That way the water doesn’t evaporate so quickly. During the fall it is beneficial to cut it a little bit shorter so that the sunlight can reach the soil.

Try not to walk on your grass.  When you walk on well-watered grass, the grass blades spring back. On a dry lawn, the grass stays beaten down, and the grass itself can be damaged. Also, heavy foot traffic on wet soil can lead to soil compaction, which keeps air from getting to grass roots.  This is a tough one for anyone with families and my advice is to pick your battles!

Sharpen those blades.  Dull mower blades shred grass, so they lose more moisture than they would with a clean cut. Also, the shredded tips turn brown, making the lawn look dull. Most grass types prefer to be mowed high, so set your blade at one of the highest settings on your mower. Taller grass grows deeper roots, and deeper roots can reach moisture that’s further down in the soil.

Don’t fertilize. Stressed-out lawns aren’t growing, so feeding them won’t help much. Instead feed before the hot, dry weather arrives. Once the weather cools down and rain returns, feed again to help your lawn recover quicker.

Consider letting your lawn go dormant. In times of drought or in late summer, one option to save water is to allow your lawn to go dormant. The blades (leaves) of the grass die, but the roots stay alive to green up again when rains become consistent. It is not the most beautiful look, but it does not harm your lawn to be brown. Do not, however, bring your lawn in and out of dormancy–that is, let it go brown and then water it to green it up and then let it go brown again. This stresses the grass, encouraging sparse turf and insect and disease problems.

Don’t go TOO long without water. In times of drought, be careful not to let the lawn go too long without water. Lawns should not go more than 6 weeks without at least one inch of water. (Measure watering by setting out a shallow pan.)

If you water, do it in the morning.  If you do not choose to let your lawn go dormant, you’ll need to commit yourself to making sure your lawn gets at least one inch of water a week—either through rainfall or from a sprinkler.  Morning, between 6AM and 10AM, is the most efficient time to water your lawn. Less is lost to evaporation and your lawn has time to dry off before nightfall because watering at night invites disease.


No Wilting Allowed.
By the time wilting has occurred, the plants are already stressed. And a wilted plant instantly becomes more susceptible to insect, disease, and other problems. Annuals have shallow root systems and so require a regular supply of water. Wiggle your finger or a stick into the soil to check.  Look at your impatiens. These thirsty plants are usually the first to show signs of dryness.

Avoid overhead watering. This can contribute to fungus growth.  For best results, water at soil level.

Don’t fertilize dry plants.  Annuals tend to quickly dry out during the day.  I often recommend routine low doses of bloom boosting fertilizer.  However, you do not want to do that to stressed overly dry plants.  Water in the morning and then come back after plants have perked up to provide their daily dose of fertilizer.

Perennials, Shrubs and Trees

Water deeply and less frequently. When watering during drought and extreme heat, remember that getting plants through the worst of the season is your goal.

Use drip irrigation or soaker hoses. There are a variety of different types of drip irrigation available to gardeners.

MULCH! Why waste what little water does make it into the garden? When choosing mulch, use only biodegradable materials that decay over time. Two to three inches of mulch should be plenty for the growing season. However, don’t put mulch up against trees because it can damage the tree from rot. Shredded leaves are also an excellent choice, but they break down faster than wood mulch and may harbor weed seeds. Bonus; earthworms love shredded leaves and will aerate your soil and fertilize plants with their castings.

Avoid rock.  Brick, stone, and concrete will absorb heat and keep your garden hotter during the summer.

Prune. Drought during the start of the growing season can cause the most damage of all, because the plants are actively growing and preparing themselves for the summer. Hopefully our plants were healthy, vigorous and mulched beforehand. After the drought, if the tops of your plants have suffered severe browning and dieback, go ahead and prune them back.  With perennials, you will often see new growth starting at the base of the plant already.

Wait to fertilize.  Without adequate water, fertilizer would either be wasted or would just cause more stress. Once the drought ends, a slow release fertilizer is best.  Choose one with a high phosphorous percentage, rather than one high in nitrogen. I like Root’n Grow by Bonide.  The phosphorous will aid in repairing the root system, where the nitrogen would encourage rapid leaf growth that could stress plants further.

Love a certain plant that is extra thirsty? Create a mini-bog for those plants that like lots of water. You’ll save water, time, and your plants will be happier! When planting, dig out a very large hole that will reach down about as far as you expect the plants’ roots to reach. Then lay a big piece of plastic down at the bottom of the hole. You can use leftover plastic liner from a water garden project, a garbage bag, or any other large piece of plastic. Cup the plastic so it forms a basin and so it almost reaches the surface of the soil. If it’s a single piece of plastic, cut several slashes in it to provide some slow drainage. Fill with good, rich soil (the kind moisture-loving plants like) and plant!