Tomato Patch: Setback or disaster?

Curled tomato leaf

Sickly—that’s the word. Thirteen of my 23 tomato plants look sick, very sick. Is this a disaster—or just a setback?

I set out my plants on May 30, and they seemed to flourish. I mulched and caged them and watered them regularly. Within a week of when I transplanted, our paving guy came to repair several cracks in our driveway and to apply a petroleum-based sealant. Fumes from the sealant were strong, so strong I opened the garage doors for two or three days to air it out. And then came those record-breaking days—99° and 100° F., or were they higher? Leaves of my 13 plants nearest the driveway began to curl, stems to twist, young leaves to shrivel, blossoms to droop.

Most affected were plants near the asphalt—Super San Marzano, Big Mama, Defiant, Virginia Sweets, Juliet, Sungold, and Wow! But two adjacent rows grew normally—three Brandywine (Sudduth’s) and three Brandywine Red, and just 25 feet downhill in another patch, a Virginia Sweets and three Yellow Plum plants flourished.

What’s going on here? I can’t recall reading an article in a gardening magazine about such trauma.

Did the plants wilt in the fumes of the petroleum asphalt sealant? Did the horrendous heat wilt the plants before they became well rooted in the garden soil? Did the heat and fumes combine to injure the plants? Did the asphalt intensify the heat to damage the nearby plants?  Or was there another cause?

I researched on online. I used the index and found relevant information in the University of Maryland Master Gardener Handbook. I went online ( and submitted a question to the consultants at the University of Maryland Extension’s Home & Garden Information Center.

The consensus is that there are multiple possible causes, so it’s difficult to pinpoint the cause with certainty. Because the leaves curl up, rather than down, herbicide (such as drifting 2,4-D) is not the answer. The most likely suspect is the effect the extreme heat we had last week had on the newly set-out plants. The sealant fumes are hard to factor in because they’re not a common cause of such problems, but in my case, plants between the asphalt and the tomatoes were not affected—peonies, daylily, spotted mint, allium, crape myrtle, butterfly weed, and Shasta daisy.

What am I going to do? I’m going to monitor my sick plants closely. HGIC asked that I report if the situation gets worse.  I plan to report next week.

Will these blossoms turn into tomatoes?

While I was mulling over possible causes of my sickly tomato plants, I had another troubling thought. Tomatoes—peppers too—have maximum fruit set between 65° and 80° F. They have reduced fruit set at temperatures greater than 95°. Temperatures last week were above 95° several days.

Did those high temperatures do double damage on my tomato plants? Did those temperatures, more like those of July and August than June, wilt my young plants and delay their growth? Did those super-hot days damage the pollen in the first blossoms—so I will have few early tomatoes if the plants do revive?

How much drama can we stand, tomato growers?

I knew I should have done a Ph.D. in botany. “Dr. Nixon, Dr. Nixon. Please report to the Tomato Patch. Code Wilt. Code Wilt.”

Ah, fantasies—always good for a smile—as would be an enclosed Tomato Patch—perhaps a greenhouse with central heating and air-conditioning—so I could keep the temperature at exactly 78° F.—for maximum fruit set.

16 Comments on “Tomato Patch: Setback or disaster?

  1. Bob – I learned this one the hard way, myself. My garden is up against the driveway, and a few years ago I had the driveway sealed, just as you described. The cucumbers were nearest the edge, and they didn't take it well at all. They shriveled, and mostly I remember a lot of the leaves turned white, and the fruits were small and shriveled as well. I, too, called HGIC, and befuddled them. The response was something like “I'd never gotten a question like that, but it doesn't sound like a good idea to spray petroleum products near food-bearing plants.” Duh…..

    Well, keep us posted, Bob, but know that you're in good company. (:


  2. That curled leaf looks all too familiar to me. Saw many of them last year and attributed it to the record heat and setting them out a little late perhaps. My 4 plants just stopped growing and flowered a little but no tomatoes. I got paranoid and thought the plants were diseased – I pulled them out before I got any fruit.

    The previous year I had great yields. This year is looking pretty good, although I do have a few leaves curling up again I have fruit set on all 6 of my plants.

    I look forward to your reports. Good luck.


  3. Thank you, this is great information! My container tomato leaf is doing the curling thing, and I suspected it was the heat. Does the temperature range for fruiting apply to other vegetable plants too? I've noticed in the last few weeks that the flowers on the eggplant are just dropping.


  4. i always worry about that leaf curl, but in my yard some varieties just seem prone to it. i have heirloom speckled roma plants whose leaves always look like that, yet they are setting fruit and are bigger by the day. it's a mystery.


  5. I attribute curling to hi temperature, I had the same experience with a tomato plant in a large clay (20 inches wide) pot on a brick patio. During a high temperature day bricks became rather hot and contributed to the discomfort of the plant. I recently read that a large plastic container is preferred to a clay pot for a tomato plant. Perhaps your black driveway emitted way too much heat.


  6. A couple of my tomato plants are doing this as well, but others look strong. However…I don't have any fruit yet, should I be worried? Lots of blossoms but no fruit. This is only my second summer attempting gardening in MD; my tomatoes didn't do well last year but I thought I had learned some lessons….


  7. Amber–i'm no expert, but i am guessing that i started my tomatoes and set them out earlier than you, which may be why i have fruit and you don't yet–i don't think you should worry. also, i've been gardening for a few years now, but harvested not a single tomato last year–the plants that didn't die from blight got predated by squirrels!

    every year, every garden spot, and every crop variety is different, so there's always more to learn!


  8. Donna: I believe the super-heat and the sealant fumes did serious damage to many of my tomato plants. I’ll keep you updated. But thanks for sharing your experience. It’s comforting to know others have experienced the same uncommon mini-disaster.

    Mike: Yes, I believe the heat and small root systems (late transplants) contributed to my problem. I didn’t enjoy the 100-degree heat either.


  9. CharmCity, Stephen, & Julie: Yes, most curling seems to be heat related, but some varieties, as Julie points out, seem more susceptible. CC & Stephen: If you used new soil this year, I think the curling must be 100% heat related. CC: High temperatures have negative impact on “cool weather” veggies, the ones that you plant in March or April. But most hot-weather veggies thrive to a point. Tomato pollen begins to degenerate when the temperature hits 90. I just read an online posting that says eggplants suffer at temperatures over 100. Julie: My MG friend, Kent P., who gave me the Big Mama, says all his have curled leaves, the only variety with the problem in his large garden.


  10. Paul: Yes, the larger the container the better, and plastic is better than clay because it retains moisture better. And, yes, I think the asphalt near my tomatoes contributed to their problem when the temperature hit 100 and above.


  11. Amber: My tomatoes are just flowering now. I planted them late—Memorial Day—so I’m not overly worried other than tomato pollen begins to suffer at 90 degrees, and we hit that temperature and more several days last week. If your plants have 8 hours or more of direct sunlight and enough water, I think you shouldn’t worry. I’ve been growing tomatoes for so long I cannot remember when I started my first patch, and I learn something every year, so smile and enjoy your Tomato Club Membership! My lesson this year is still developing—and it has something to do with high temperatures and fumes from asphalt sealant.


  12. Good news, as of today when I took a closer look, I have some teeny fruits on 2 of my plants! Blossoms on all but one plant, which is one of the more sickly looking ones. Thanks for the replies! Here's hoping they keep growing.


  13. My 3 plants have up curling leaves. They are green on top and have almost a navy color on bottom. They all are strong upright lots of flowers and starts of fruit. Are they ok? No bugs chewing or visual of anything else.


  14. Hi Susan – Sounds like your plants are doing well and may have experienced a temporary setback due to high heat. Leaf curl is pretty common with tomatoes, especially certain varieties, when they are stressed. Make sure they are getting watered deeply several times a week (if you are local, this week's rain should have helped!). Blue/purple color can be a symptom of phosphorus deficiency, or it can be natural to certain cultivars. If the plants look well and are producing they will probably do fine. It's a good idea to get a soil test, though – see


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