Although many herbs and fruits will bear for many years, most gardeners grow vegetables as annuals. There are some exceptions that can, depending on your climate of course, be harvested for years to come.
Perennials are different than self-seeding annuals, but for the topic at hand we are grouping them together.
Here in Zone 5/6 we can count on:
1. Lovage is technically considered an herb, but we list it here because it is used as a vegetable. The leaves particularly and the stems as well can be used in place of celery. Be sure you have enough room before you plant it, as lovage can easily grow 3 ft. wide and over 6 ft. tall.
2. Good King Henry is a new plant for our garden this year. It is reputed to taste much like asparagus, but with a longer harvest period. Eat the leaves raw or steamed. Give it a space of its own, as it will reseed with abandon.
3. Horseradish can easily be grown from a root purchased at your local market. It can be quite invasive, so we recommend planting it in a pot that sits on top of a rock slate, as the tiny roots will do their best to get out. Be forewarned, fresh horseradish packs an amazing punch.
4. Jerusalem Artichokes aka Sunchokes are as delightful to see grow as they are to eat. A relative of sunflowers, their blooms are similar but smaller. Even better, they smell like chocolate. Harvest the roots after the flowers fall over. Enjoy like a water chestnut or as a potato substitute.
5. Radicchio aka Italian Dandelion is a relative of what many consider to be an invasive weed. "You're planting what?" was my husband Mandolin Jones' reaction when I mentioned 'dandelion' but he was okay with 'radicchio'. According to Art, the master gardener from Baker Creek, we should get 2 years of harvest here in Zone 5/6. So we intend to replant again in year two and see what happens. Some perennials last longer than others.
6. Rhubarb is one of the first veggies to pop through the soil in spring. It will last basically forever, as long as it is cared for. When you see it is looking overcrowded, dig some of the roots up and share. We found out the hard way that the best thing to do with dug roots is to pot them up for a year before transplanting. Live, garden, and learn.
7. Asparagus is probably the best known perennial vegetable. Harvest lightly after the first year, a little more the second, then have at it afterwards. We have heard of asparagus beds still thriving after 20 years.
8. Walking Onions aka Perennial Onions have a few other common names as well. They reproduce themselves by 'walking', that is, bending a stem over and dropping little bulbules or topsets on the soil. Use like scallions.
9. New Zealand Spinach is not actually a spinach, but a wonderful self reseeding substitute. Be sure to plant it in a relatively weed free area and let it have fun.
10. Garlic is one plant we never thought of as a perennial. A coworker discovered this by accident, after neglecting her garden one year. Her garlic also produced little topsets and replanted itself. It has been 3 years now and she continues to get garlic without ever planting more. Not just greens, but normal sized cloves. You know we will be trying this!
NOTE: Before planting any perennials, be sure they will grow in your area and not be invasive.
Specific growing information on many of these edibles can be found on the list to the right.