IS IT NATURE (as in genetics) or nurture (as in where and how you raise it) that makes for a tasty tomato? I asked a university breeder and geneticist, and a seed farmer and breeder—each with decades of expertise in Lycopersicon esculentum: How do you grow the best tomato?
I’m often asked that question, usually phrased like this: Why didn’t my (insert name of tomato variety) taste as good this year as last?
Getting the best flavor from a tomato is “a matter of lining the genetics up with the environment,” says Tom Stearns, founder of High Mowing Organic Seeds. It’s something he acknowledges that people are more inclined to do with animals than plants—to choose a breed of livestock suited to their region, for instance, but not to choose their tomato or other seeds that way.
But both are living creatures that have adapted over generations to their environments, so the same logic should be applied.
“Here’s how I think,” Stearns says: “The final flavor of a tomato is 60 percent genetics, and 40 percent environment.
“If you have a tomato that was bred and selected for the environment you’re growing it in, then you can get to the pinnacle of that variety’s taste: 100 percent is possible.”
For example, you have maximum potential if you grow a Northeast-bred and -selected variety in the Northeast—meaning it’s not just a variety said to be suited to your area, but that the actual contents of the seed packet you began with were raised in conditions like yours.
“But what if it’s a Florida-produced variety, and you grow it in the Northeast?” says Stearns. “Either the genetics (or the environment) won’t be fully in your favor.” No home run possible.
The same is true with tomato seed grown in conventional agriculture (using synthetic chemical inputs such as fertilizer) versus seed grown organically. Carefully matching up the seed you start with to the cultural conditions in your garden is another environmental or “nurture” factor in the equation.
We all want to start with a tomato variety that is knows for its taste (sorry, supermarket varieties, but you’re not even in the running).
Though “sweeter” tomatoes have more flavor, the experience we call flavor in tomatoes derives from an interaction of multiple factors, including the ratios of sugars, acids, and volatile compounds.
In general, heirlooms (which are open-pollinated) have better flavor than hybrids, says Dilip Panthee, Assistant Professor of Tomato Breeding and Genetics at North Carolina State University, and, “in terms of size, generally small-fruited tomatoes were found to have better flavor than large-fruited ones.” Why?
“It might be because the flavor-contributing components, including total soluble solids (TSS), total titratable acidity (TTA) and others, may be in concentrated forms.”
Panthee has been working with molecular biologists from the USDA’s Agricultural Research Service on a project aimed to breed more flavorful commercial tomato varieties—tomatoes that don’t just ripen all at once or ship easily to the supermarkets, the way large-scale farmers prefer, but also taste like, well, a tomato (and not cardboard).
Both Panthee and Stearns agree that environment plays a big role in the flavor of the harvest.
Growing conditions with too much rain or irrigation water would impair taste, says Panthee. “Less rainfall and more sunshine will increase the flavor of tomatoes,” he explains. One environmental reason tomatoes grown commercially have poor flavor relative to garden-grown ones: gardeners use less water.
“Soil types that can hold moisture for a relatively long time (without water stagnation) may improve the flavor of a tomato,” says Panthee, “because it avoids frequent irrigation and helps preserve nutrients.”
In his “40 percent environmental” equation, Stearns also includes these other factors, besides water and light:
“Soil temperature, air temperature, night temperature, extreme swings that occur in temperature—and disease and insect pressure, too,” he says. “But some of these are counter-intuitive: For example, sometimes under pest pressure, the flavor might improve!”
So how do you like that first slice or wedge of garden-fresh tomato–plain, or perhaps with a sprinkle of salt? Apparently the tomato plant itself likes a dash (though I won’t be trying this last scientific “aha” in the garden).
“Tomatoes grown under salt-stress conditions are flavorful, because salt regulates their water uptake,” says Panthee about one of his less-expected research findings. “However, at the same time, salt is toxic to the plant. If the toxic effect can be avoided, growing tomato plants under salty conditions helps to produce flavorful tomatoes.”
With tomatoes as with humans, apparently: everything in moderation—and both nature and nurture figure into the finished product.