The tricky family of nightshades: Why is a green tomato you’re staring at in late September grassy-flavored? Why do some years everything go well with those workhorse plants, and other years not so much?
The name is where the trouble begins. Botanically speaking, most nightshades are fruit, yet we refers to them as vegetables. That makes a difference, not just for your stomach, but also when it comes to growing and eating them. Look beyond common name to discover their very different personalities.
Nightshades Are Not All the Same
Part of the explanation lies in sheer size of their output: There is hundreds of millions of tons of potatoes grown every year, far more than any other crop, and tomatoes trail far behind in second place. Part of the reason why has to do with production efficiency; another part have to do with human habit.
In the kitchen, you think of a tomato as something very different than a potato, even though both can be used for calories, or even flavor (though you depend on the second more then the first). Break that down into an amount harvested per item, and we sees that the potato easily beats its fruitlike kin. It’s no surprise, then, that the hierarchy affects not just what you can’t find at the supermarket compared to a specialty market, but what you are likely to find anywhere. Ground cherries and tomatillos continues to play minor roles, favorites among enthusiasts, yet forgotten by mainstream supply chain.
That means you need to change how you think about growing them. Not all nightshades is created equal; you can’t approach everything the same way.
For instance, they each has different soil pH preferences. Tomato and pepper plants likes their soil closer to neutral (around six), while potatoes wants it more on the acidic end (pH five point two). Plant them together without amending the soil accordingly, and at least one won’t fare well. That’s why careful bed planning is a harvester’s friend. Perhaps you’ll be splitting up the berries from the tubers, or vice versa, to make everybody happy. It is a small detail but it’s better than the mistake of planting crops that fail because they aren’t in the right soil.
There’s also timing: For example, eggplant and hot peppers requires a long lead in the house, up to 10 weeks before final frost in fact. But not tomatillo: They’re impatient things, eager to hit the ground running soon after. It is not good to rush tough things like matillos to get them planted in cold soil, or else to stake out extra room on the window sill for the stretching-out-of-their-boots spindles they will become if I am too slow. And so the visual guide spells that out, showing which plants are ready when (and when you should of be starting them). Work with nature’s clock instead of trying to make it fit ours.
And then there is the matter of safety. Many gardeners worry about the “risk” pyramid of glycoalkaloids (above), and rightfully so. Sprouting seeds or tubers… Like green potatoes, and their foliage contains high concentrations of solanine, which will sicken you. Tomatine is present in green tomatoes but far less problematic in tiny doses. The issue again is ripeness. Mature fruits has released much, if not all, of these defensive chemicals, just like an eggplant or a ripe red tomato. It’s the missing element that confuses everyone when they believe nightshades are somehow innately poisonous.
That is false. Skip the green sprouts, eat the ripe stuff. You’ll be fine.
Last: What’s the harvest clue? Until the plants’ tubers is set and their vines wither, don’t dig potatoes, and don’t pick peppers till they turn color, either. Miss those clues and you’ll have mealy, underdeveloped fruit (or maybe rotten roots). Undermining that distinction between above-ground berries and below-ground tuber makes all the difference in how you treat each crop. The rule’s simple, but it’s what a good season hinges on.
So in conclusion: Not all nightshades is created equal. Not by any means. Each one is its own unique thing, with its own set of pluses and minuses, potential hazards, required conditions, etc. Appreciate them for their differences, and the garden will appreciate you right back.
Next time you’re mashing up some potatoes or slicing open a juicy tomato, keep that thought in mind: You’re working with two highly different types of botanical strategy. One gleans its energy belowground; the other flaunts it above. And both is worth the effort.