The last thing we want to do is to turn customers off to vegetable gardening. As tempting as these selections appear, though, a few of them must be approached with caution. Just because an edible plant is, well, edible, that doesn’t mean that every part of it is good for you. And if children are involved, or if pets have the run of the property, it’s a good idea to instruct your customers on what to keep and what to toss.

Thanks to the Minnesota Department of Agriculture, which issues a handy “Weed of the Month” alert, we know that potatoes and rhubarb, two staples of the home food garden, have parts we’d be wise to avoid. (Thanks also to Roy Benson, who taught his daughter very early that the huge leaves of rhubarb, which his daughter used to employ as play umbrellas while she consumed every strawberry in the garden, should not be munched.)

The most popular veggie around—potato —is among the most versatile, too. But its leaves and sprouts can cause wretched symptoms if ingested.

Rhubarb (Rheum rhabarbarum) is widely grown for its colorful and fleshy stalks, whose tartness is favored for use in pies, crumbles and fool (look it up), among many other tasty treats. The leaves, however, contain oxalic acid as well as the possibility of anthraquinone glycosides, according to the National Institutes of Health, which can cause symptoms that range from burning in the mouth to vomiting to coma. However—and this is a significant “however”—a large serving of leaves must be ingested to produce ill effects. The age, weight and general condition of the person who eats rhubarb leaves affect the severity of symptoms, which means that children (and pets) generally are more at risk than healthy adults.

Read more: 2016 is the Year of the Carrot

Potatoes, everyone’s favorite starch, are members of the Solanaceae, or nightshade family. Anyone who’s read pulp mystery novels knows that “deadly nightshade” is the dastardly villain’s poison of choice. Atropa belladonna (deadly nightshade) is among the most toxic plants known, and many an unsuspecting damsel fell victim to its poison.

Not so with potatoes. Solanaceae is a large family that includes tomato (Solanum lycopersicum), eggplant (S. melongena) and potato (S. tuberosum), among many other ornamentals and, yes, bad actors. But even though potatoes are the most commonly consumed vegetable in the U.S.—more than 48 pounds of potatoes (in various forms) per person were consumed in the U.S. in 2013, according to the USDA’s Economic Research Service—there are parts of the potato plant that are not friendly.

The rather hairy leaves can cause irritation or rash upon contact with sensitive skin. And tubers that have turned green or have sprouted due to exposure to sunlight contain high amounts of solanine—these should never be eaten. Solanine is toxic even in very small amounts, so tell your customers to toss new sprouts, spoiled potatoes and any potato that has turned green below the skin.

All of this is to say, let’s not scare eager home gardeners away from planting vegetables. But let’s be responsible, and give them the appropriate facts.

Read more: 5 Ways to Experiment with Unusal Edible Plants

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