Question. I'm new to growing vegetables and trying to find information on which are perennial, but nothing tells me which ones come back. Obviously carrots, potatoes and corn do not, but should cukes, tomatoes, eggplant or peppers be left in the ground at the end of the season? Or will they just die off? I am, as they say, clueless. Thanks!
- ---Stephanie in Voorhees, NJ
Most of the plants you named are true annuals; they last one season and then die even if protected from frost. Carrots, however, are biennials; if you leave the roots in the ground, the tops will flower the following year and produce carrot seed for you—although the second-year carrots themselves will have turned bitter.
Potatoes often seem perennial. That's because it's easy to miss the odd spud at harvest time, and these buried treasures reliably survive winter to produce new 'volunteer' plants the following season. Cherry tomatoes are notorious for this; the seeds in their dropped fruit always sprout the following season. And peppers are truly perennial. Not outdoors in New Jersey, of course—you have to bring them inside and keep them under bright light for the winter. But in non-freezing areas in Southern Florida, California and Arizona peppers are perennial outdoors. I've seen 20-year old habanero trees in Santa Fe.
The best-known true perennial vegetable is asparagus. Plant the crowns in Spring, be patient the first few years, and you'll harvest 6 to 8 weeks of good eatin' every Spring thereafter. And gardeners who can perennialize their peppers outdoors can't grow asparagus; it only thrives in areas with winter freezes. We'll link up to a Previous Question of the Week on asparagus that provides lots of growing and harvesting info.
Another true perennial is Rhubarb. The only vegetable we eat as a fruit, it also goes into the ground in Spring and should only be harvested lightly—if at all—the first couple of seasons. Then you'll harvest lots of ripe stalks every Spring. Remove every bit of the (poisonous) leaf and use the tasty—and safely edible—stalks to make rhubarb pie. This plant requires good drainage, likes a heavy feeding with compost or well-composted manure every Spring and Summer, and, like asparagus, only grows well in areas with winter freezes. Cut off any flowers that form after harvest, and divide the clumps every couple of years to keep production high.
Jerusalem artichokes are worse then perennial—the plants are invasive as all get-out! The knobby tubers—also called 'sunchokes'—are generally cooked like potatoes, taste best after winter frost sweetens them up, and don't get very tasty in warm climes. But many gardeners don't care; they plant the tubers—in a well-contained area—just for the riot of chocolate-scented daisy/sunflower-like blooms that appear prolifically above ground. You plant the tubers in the Spring, the above-ground growth dies back every winter, and the plants re-grow from the buried tubers year after year, often becoming pestiferous. Oh, and they're native to North America, not the Middle East. "Jerusalem" is likely a corruption of the Italian word for sunflower, and somebody apparently thought the tubers looked like artichokes. (They do not.)
Egyptian onions are perennial members of the Allium family (onions, garlic, leeks, etc.) with a very strong flavor. The underground clump survives winter to produce shoots that can be used like scallions when young, leaf tips that make a good chive substitute, and a white, leek-like base that people use as the 'onion' part. You don't eat the underground bulb. They grow anywhere; heavy watering in summer will tame the flavor a bit.
Potato, or 'multiplier' onions are a fun plant with a mild onion flavor and a solid history as an heirloom favorite in America, although planting stock can be hard to find. These members of the Allium family are planted in the Fall and produce lots of little green onions—just like the 'sets' used for regular onion planting—in the Spring. These become large, high-quality storage onions mid-summer. You harvest when the tops die down, just like regular onions; but much earlier in the season. Leave some little ones and big ones in the soil and the following year the little ones will produce big onions and the big ones will give birth to little ones. They grow from the top of the country to the bottom and from Sea to Shining Sea.
Good King Henry is a perennial green that tastes like asparagus in early Spring, spinach in late Spring, turns bitter for the summer, and then returns with another double dose of edibles every season. It thrives pretty much everywhere, as does sorrel, another leafy perennial. Water your sorrel well, and the leaves will retain their desired slightly sour lemony taste. Without water they get tough and bitter.