Tagawa Gardens Blog

Mid-Summer Tomato Problems? Here Are the Answers You’re Looking For

tomato tone soil pep tomatoes at tagawa gardens denver

$3 OFF Tomato-Tone and Soil Pep Mulch

Stop by Tagawa Gardens before 7-26-17 and Receive $3 OFF Each 4 lb. Bag of Espoma Tomato-Tone Tomato Food AND $3 OFF Each 2 cu ft Bag of Soil Pep Mulch. 
Find Your Coupons at the end of the article.

Here at Tagawa Gardens, our plant advisers at Dick’s Corner are getting lots of questions about tomato problems.  One of the most common complaints is about tomato leaves rolling inward. That’s a classic symptom of heat stress.

Hot! Hot! Hot

For the past six weeks, our temperatures have consistently been above average.  Even with plenty of water, plants can still react to temps outside of their “comfort zone.” Tomatoes are heat-loving plants, but our sizzling temperatures for the past several weeks are just too much of a good thing.

It’s called “physiological leaf roll.”  It’s not a disease.  It’s how the plant is responding to something in its environment.  With tomatoes, daytime temperatures that are consistently above 90 degrees can prompt the plant to go into survival mode.  The oldest leaves cup, and if the stress continues, they roll inward.  The plant is trying to reduce moisture loss by reducing the amount of leaf surface exposed to the hot sun.  The leaves may also become thick and leathery.

Sometimes the leaves will relax and open up as the weather cools down.  The leaves on my plant (shown above) are still curled.  The good news is that the rolled foliage doesn’t seem to be significantly slow down the development of the fruit that had already set.

But another heat-related problem is putting a dent in my crop.

Tomato pollen is sensitive stuff!

The tomatoes we grow in our backyard gardens are self-pollinating.  A bit of wind now and then (or an occasional “thump” on the stem from an attentive gardener) moves the pollen within the blossom and the job is done.


But temperatures above 93 degrees or so damage the pollen.  The flower doesn’t get pollinated.  It dries up and simply falls off, leaving nothing but the tiny stem that once held it in place. Fortunately, if the plant is healthy otherwise, more blossoms will develop once the weather cools down.

Time for some shade?

It is possible to help tomato plants during a heat wave by creating a little shade. Tagawa Gardens sells shade cloth that can protect tomato plants from the hottest part of the day. You’ll need to create a support to hold the shade cloth off of the plant, but the extra effort may be worth it to you.

Gardens can also be situated in such a way that taller plants offer some protection from the strongest early- to mid-afternoon sun.  A bit of shade from taller plants or cloth can easily reduce the damaging temperatures enough to prevent both leaf curl and blossom drop.

One more high-heat threat

Not all of the problems we’re seeing on our tomatoes can be blamed on Mother Nature. Some of them are our fault!  This next issue is a prime example.


This is what herbicide damage looks like.  And our garden advisers at Dick’s Corner are seeing a lot of it, including on tomatoes.

All herbicide packaging comes with detailed instructions for very good reasons.  The “rules” go beyond mixing the chemicals in the right proportions, which is critically important.  The labels also caution against using herbicides when the weather is especially warm or windy, and certainly when it is both.

When the air is warmer than than the guidelines listed on the package, what comes out of your sprayer as a liquid can quickly and easily become a gas.  You won’t see it, but this cloud can drift onto near-by plants and cause extensive and irreversible damage.  The “drift” may or may not kill those desirable plants, but it will permanently distort the foliage that it hits.

Our advisers at Dick’s Corner have also seen damage to tomatoes after a gardener mulched her plants with lawn clippings from turf that had been treated much earlier in the season with a weed-and-feed type fertilizer.   The toxic ingredients in many herbicides can be very persistent, and caution is needed when you use them.  Tomatoes are especially sensitive to these chemicals.

Some tomato T.L.C. tips

As a group, tomatoes can be demanding.  But they’re still by far the most popular garden vegetable.  No contest!

In addition to the topics outlined above, here are some basic guidelines to get the best tomato crop possible.

  • Water your plants thoroughly, applying enough water to penetrate down to the deepest roots.  Try to avoid overhead watering, irrigating instead at the base of the plant.
  • Mulch your plants to preserve moisture and keep roots cooler.
  • Remove the lowest branches so all of the plant’s leaves are at least six to eight inches above the soil.  This will help reduce disease.
  • Fertilize appropriately… not too much and not too little.  A vigorous plant can stand up to stress much better than a weak one.


We all start the season envisioning robust, healthy tomato plants.  But if you have problems, I encourage you to bring a fresh, bagged sample of your plant to our garden advisers at Dick’s Corner.  Cell phone pictures of your plants are a big help, too.

And check out another of my blogs that deal with tomato issues that might come up a bit later in the gardening season. Click Here to view Help, My Tomatoes Aren’t Cooperating!

Even when they require a fair bit of pampering, I’m a dedicated and determined tomato grower!  The harvest can’t come soon enough for me!

Please follow and like us:
Luan Akin
Luan Akin
Tagawa Gardens Outreach Ambassador

After 30 years as a news reporter for KCNC TV in Denver, Luan Akin was ready for a change. In 2008, she came to Tagawa Gardens and offered to create a brand new position: Garden Outreach Ambassador.

Luan had trained and volunteered as a Douglas County Master Gardener for ten years. In addition to her duties as a news reporter, working primarily out of the Channel 4 News helicopter, Luan also produced and presented a long-running series of stories called “Gardening Together.”

All these years later, Luan now works year ‘round, presenting a variety of gardening and nature-related topics to hundreds of children, HOA’s, gardening clubs, church groups, small businesses and other organizations.

She is an avid gardener, a beekeeper and a proud mom to four dogs who have trained her well.


  1. Marie Hanson

    July 14, 2017 - 3:09 am

    Thank you so much for sharing this information…..very interesting and helpful

    • Luan Akin

      Luan Akin

      July 17, 2017 - 6:03 pm

      Thanks for checking out the blog. Looks like we’re in for another very hot week, so not likely to get any new tomato blossoms. Gotta love the tomatoes we get!


Leave a Reply

Your email address will not be published. Required fields are marked *

Enjoy this blog? Please spread the word :)