Rex Trulove
Gardeners have long known that tomatoes grow best in calcium-rich, well-draining soil, with the tomatoes receiving lots of sunlight each day. It is also common knowledge that the weather plays a big part in growing them successfully. You might be surprised at the aspect of weather that has the biggest impact of all, though.
The person who did the study was Frits W. Went. He was a Dutch botanist who was a professor of botany at the University of Utrecht. He was also the director of the botanical garden in the same location. (His son, also named Frits Went, is also a botanist.)
It had long been known that the stable climate of southern California was nearly ideal for growing tomatoes. Professor Went wanted to determine which aspect of the climate was the most important for tomatoes. The implications of that knowledge were great since if people knew this, that aspect of growing tomatoes could be emulated elsewhere, at least to some degree.
The professor got his chance when he had the opportunity to grow tomatoes in a strictly controlled environment that could be altered to mimic virtually any climate or season. He could alter variables like temperature, humidity, wind, and light.
The findings, though simple and straightforward, were incredibly enlightening. His studies proved that the biggest factor in producing tomato fruits was the temperature. More surprising was that the controlling factor was only the temperature at night. The temperature during the day had little effect.
It was found that tomatoes only set fruit if the temperature at night was between 60 F / 15.5 C and 75 F / 23.8 C. If the nighttime temperatures dropped below 60 or got above 75, the tomatoes didn’t produce any fruits, no matter how all other climatic variables were changed.
This, more than any other reason, explains why California leads the US in tomato production.
Professor Went also determined which temperatures were optimum for many other plants, and for most other plants it was also the nighttime temperature that was important, rather than daytime temperatures. For instance, potatoes, though they are in the same family, require temperatures at night that are below 53 F / 11.6 C to produce tubers.
Since this is below the minimum temperatures needed by tomatoes in order to set fruit, it also explains why areas can be great for potato production or they can be terrific for tomato production, but they are rarely good for growing both potatoes and tomatoes. Thus, California leads the US in tomato production but Idaho and southern Oregon leads the nation in potato production.
There isn’t much as home gardeners that we can do about the weather, except in greenhouse conditions. However, it easily explains why you can have a terrific year for growing tomatoes in one year but a lousy one, the next. When that happens, gardeners normally try to figure out what they did during the growing season one year that they didn’t do the following year.
As it turns out, it probably wasn’t anything you did or didn’t do. Instead, it was most likely the nightly temperatures in your location that had the main impact on growing tomatoes.
This is pretty interesting, isn’t it?
Thanks for this information! I am glad to know the night temps for both potatoes and tomatoes, since I got this greenhouse now. I pinned this for later.
It is super if it can help you! I’m hoping that this will be a good tomato year.
I don’t like tomatoes raw, but I have been trying to grow them to can tomato sauce for the last three years. I am not sure why, but I just don’t have any luck. I planted 7 plants last year and I think I got 8 or 9 tomatoes. It’s like they know I don’t like them……lol.
The nighttime temperature might have a lot to do with it. An easy way to tell if the other conditions are right is by trying to grow peppers and/or eggplants. If these grow fine, it is most likely the nighttime temperatures that are preventing you from having larger crops of tomatoes.
I should explain that the reason for growing peppers/eggplants is that tomatoes have the same requirements for soil, sunlight, and water.
That is just funny! They don`t know. Talk to them tell them how good they will taste in the chili! 😀
I love really fresh tomatoes, and usually grow them in my greenhouse, but there’s no way I can maintain a minimum of 15.5 if the ambient temperature doesn’t reach near it. This explains a lot.
One thing I don’t think you explained is what an area that is good for growing tomatoes might not be good for potatoes. As you said, their minimum requirement is lower, but that doesn’t in itself explain. I’m asking because I recently saw a video of someone grafting a tomato onto a potato plant which on the face of it is a nicely productive idea, and I was thinking of doing this here.
You could maintain that sort of nighttime temperatures, most likely, if you added another heat source to the greenhouse. For instance, if you put some black water barrels in the greenhouse, the water can absorb heat during the day and radiate it back into the air at night. That is just a thought.
Part of the reason why potatoes don’t produce lots of big tubers when the temperatures at night get too high is that the production of auxin in the potato plant drops when the temperatures get too high. The same is true of tomatoes, but the temperature range is simply different between the two plants.
The amount of auxin produced by the potatoes drops when nighttime temperatures are too high, but it doesn’t stop altogether. For that reason, a tomato-potato graft would probably work, if the nighttime temperatures were kept as close to 15.5 as possible. At that temperature, the potato would probably produce just a few small tubers, but it should still produce them. The tomato would probably also produce a light crop since that is the minimum temperature for which they will set fruit. Still, the auxin produced by the tomato part of the graft would be independent of the auxin produced by the potato stock.
Tomatoes that we buy here look and taste like plastic. I have a decent garden so though why not plant them here. I think summer temperatures in Belgium are okay for tomatoes
My guess would be that the commercial tomato growers there keep the tomatoes refrigerated. That leads to the tomatoes tasting very bland, with more starch content than sugar content. Tomatoes shouldn’t be refrigerated.
If you have reasonably cool nights in the late spring to early summer, they probably grow well there.
It is very interesting. My Dad always grew tomatoes. I need to start now.
I love them especially as a sandwich.
I’d be hard-pressed to think of a way that they can be used that I don’t like. :)) I love tomato sandwiches, too, and also like them in other kinds of sandwiches, like ham, beef, chicken, and even grilled cheese. I also like tomato salads.
Nothing can beat a fresh tomato from the garden.
You’ll get no argument from me about that.
I am not big fan of tomatoes but thank you!
I totally love tomatoes, especially if they are garden fresh. If I have enough, I home can them.