July 5th, 2008
Hot Tomato

This ‘Green Pineapple’ tomato set only one fruit before the heat set in because I planted it much too late.

On June 25th, Carol over at May Dreams Gardens in Indiana is rejoicing that her tomatoes are finally big enough to start tying up. In contrast, here in Austin, Lancashire rose is pulling hers out by June 21st. This is a fine illustration of what Austin gardeners face. While most of the world’s attention concerning tomato season is focused on first and last frost, worrying about setting plants out too early or being disappointed by an early freeze, we southern gardeners face another threat: heat.

If you measure the growing season as the time between first and last frost, then Austin has an incredibly long one. Our last frost is officially mid-March, although many Austin gardeners can’t resist a little gamble and start setting out plants a by Valentine’s Day. Austin’s first freeze often snarls Thanksgiving traffic. But yes, our freezes are short-lived. Our plants don’t go dormant. Our ground doesn’t freeze. So we can have flowers every month of the year.

However, it’s my experience that Austin doesn’t have a marvelously long growing season but two short ones, interrupted by that disaster known as summer. For example, tomatoes set fruit best if the day time highs are below 90F and the night time highs below 70F. Some research shows that “night temperature is the critical factor in setting tomato fruit, the optimal range being 59-68°F”.

In 2008, April was an ideal month for tomato fruit set. The high didn’t get out of the 80s and the lows ranged from 41-72. Within less than a month, the highs were in the 90s and 100s and the lows mostly in the 70s. If you didn’t have your tomatoes in and flowering by April, you missed out. Last year it was October before the temperatures fell into the correct temperature range for tomato set. That leaves a pretty small window before Austin’s first freeze.

I know from reading other Austin garden bloggers that there are a lot of successful tomato growers in this town. Will you share the secret of your success? Do you plant short-season tomatoes? Do you have some favorite heat-tolerant varieties (tomatoes that set fruit in temperatures higher than the average tomato can handle)? When do you put your plants in? And, do you pull them out over summer and start over in the fall? or do you try to nurse them through the heat?

by M Sinclair Stevens

11 Responses to post “Hot Tomato”

  1. From Julia:

    The secret, don’t try – no not really. heat tolerant varieties (Celebrity, Carnaval) and heirlooms (yep, they’re tough), tons of mulch and drip irrigation. But when the temps are over 80 at night, tomatoes won’t set fruit. Shade cloth for part of the day or shading the late afternoon cooking sun may help them survive. Honestly, our best tomato growing season is fall – you can cut them back and see if they come back, but I usually start with fresh bedding plants. For now, just plant Okra and stand back. Personally I gave up on the Tomatoes till fall this year.

  2. From Carol, May Dreams Gardens:

    Sorry I’m not any help at all, but I read somewhere, can’t remember where, that tomato plants won’t grow when temp is below 59.5 F. I’m sure that is not helpful for you to know!

    And, I just saw a picture of the most delicious looking tomato slice on Annie in Austin’s blog this evening.

    It’s summer, we are all trying to get a decent tomato, no matter where we garden!

  3. From Rachel from Austin:

    We’ve had a modest tomato harvest this year. (Last year’s cool rainy summer gave us more tomatoes than we knew what to do with off of three plants.) I think I planted in March or April, but some of the plants I started with were the nice tall ones I picked up at the Zilker garden festival. If I have a secret (and I’m not sure I’m a successful enough gardener to have an official secret), it’s choosing several different varieties. I love Early Girl because it’s the first tomato in my garden to set fruit (and ripen) in the spring. It’s done by the time the hot weather plants start working in overdrive.

    We’ve been alright in the heat this year, though – my plants are still producing, though not in great quantities. We try to keep them well watered, and they don’t get as much sun as I’d like – but the part-shade may help them survive in our crazy heat.

    Last year when we had our bumper crop, I was watering about weekly with seaweed emulsion. I haven’t done that as often this year, so I have a hard time comparing, but that might help keep plants going strong in the summer heat, as well. Really, this year our biggest trouble has been those pesky stinkbugs, who like to suck the juice out of my tomatoes.

  4. From Rachel from Austin:

    I should add, for reference, that we have… I’m not even sure how many tomato plants in the ground. Easily, we have seven or eight plants, some full-sized and some cherry or plum types. From that, we’ve been getting a tomato every couple of days or so, with peaks of 2-3 tomatoes per day at times. We’ve had enough to share some with our friends and coworkers during the Tomato Crisis of 2008(tm), but not as many as you’d hope from 7+ plants! So it isn’t as though I’m a tomato-growing genius, but my plants are still producing in limited quantities.

  5. From Steve Mudge(Fort Worth):

    We have a 25 foot row of tomatoes on a trellis against an east facing wall–this gives them plenty of sunlight but shields them in the late afternoon heat blast. We get sporadic fruiting this time of year–enough for our salads and such. The cherry tomato seems to be the most productive in the heat. I generally don’t cut the plants back during the summer–just water them as needed and douse with a little foliar fertilizer. The okra, eggplant, and peppers are getting most of our attention for the next couple months while the tomatoes lie low for the fall fling.

  6. From Annie in Austin:

    MSS, as you know, Central Texas weather brings a huge element of luck to all gardening, but we tried to tip the odds in our favor:
    Philo gave our little patch one of the best sites in the entire yard, with good early sun, some shade with a slight slope for drainage.
    He then spent nearly 4 years improving the soil.
    I hand-water & patrol daily for leaf-footed bugs, and rotate among several organic foliar feeds every 5-7 days and pick any tomato showing a hint of color to ripen inside.

    Our “crop” is not impressive by our previous Midwest standards, but we get a couple of mid-size tomatoes a day and steady handfuls of ‘Juliets’. This might be pretty decent for Austin, but sure isn’t enough for Philo, who was used to popping half-a-dozen tomatoes as an appetizer before dinner every day when we gardened in Illinois.

    Annie at the Transplantable Rose

  7. From Jenny Austin:

    It has been a bad year for me on the tomato front but never fear there is fall to come and if you cut back your plants now about halfway or to a good shoot then they will grow over the upcoming weeks and set fruit by late summer when the night time temperature go down. There are still a few in the stores but not much selection. Any green ones you have you can make green tomato chutney- I have a wonderful recipe and it goes with lots of dishes especially curry.

  8. From vertie:

    No tips from my bed, but the Town Lake garden is actually doing a bit better. I think it’s because the tomatoes are getting some shade. i was actually worried we wouldn’t get any tomatoes because of the shade and now I think it’s the shade that is saving them. Last week I covered a couple of low-hanging vines with mulch. i hope I will be able to get a couple of new plants for a second harvest from them. It was Bonnie’s idea via Skip Richter.

  9. From Bob Pool:

    I wish I could help as well, but alas am not doing any better than the others. I only pick one every few days and have some plants that have not set a fruit yet, one being my heirloom Lacy tomato. This is the biggest and best tasting tomato I know. It has been grown by Mr. Lacy’s family since the middle 1800’s. He told me yesterday that he got one this year and he knows a lot about growing tomatoes. So I guess it’s not all our fault.

  10. From Pam/Digging:

    Whew, after reading how hard it is to grow tomatoes here in Austin, and hearing what small returns one gets for the effort, I think I’ll continue to take Julia’s advice and not grow any.

  11. From Bonnie:

    Agreed, this year is tough, especially after last year we had tomatoes raining down from the sky because of the low temps and rain. My only producer from spring was Jetsetter because it is designed to keep setting fruit. Just yesterday, I cut all tomato plants back by half to see if I can liven them up for fall.

    And as Vert said, Skip Richter, Director at the Extension office, says to take a branch of your tomato plant, lean it to the ground and pile soil over part of it. Give it a few weeks to grow roots then sever it from the mother plant. Voila, new tomato plant for fall!