Tree collards are one of my favorites. They are extremely hardy and extremely nutritious- with lots of vitamins, protein and calcium. They are one of the few veggies that will grow during Oregon's wet, cloudy winters. I've got several big plants that about 7 or 8 years old now in my garden. Other perennials I like include asparagus (Purple Passion from seed), Egyptian Walking and Multiplier onions, Purple Sprouting broccoli, various kinds of garlic (for greens), Giant Musselburgh leeks (harvest only the top), Moss Curled parsley, Red Russian Kale. I also have a bunch of other brassicas that have lasted for years- including January King cabbage and Thompson broccoli- just prune off all the flowers before they open and keep them well-fertilized with compost and lime. Territorial Seed Company also has several seed mixes that often naturalize, over-winter and self-seed in Oregon's climate- including Wild Garden Kales, Wild Garden Lettuce and Wild Garden Mustards. I also have made Utah Celery and Bright Lights Chard last for three years. However, I have had bad luck with Jersey Knight asparagus and Green Globe artichokes, they donot seem to like our climate.
Of course it depends on your climate, but I second the Egyptian walking onions: really handy and super tough.
Jerusalem artichokes are incredibly productive. Be aware that wherever they are planted is basically where they will always be :
Rocoto chillies. Perennial high-altitude chilli. Gangly plant, almost 'viny'. Loads of fruity, yet hot pods like Chinese lanterns.
Garlic's a perennial if I forget one or two and leave them in.
Do herbs count as veges? Thyme, sage, chives, mint, Vietnamese mint, oregano, rosemary, bay..
Rhubarb's a plant we think of as a fruit rather than a vege; whatever I call it, my 'Glaskin's perpetual' produces fat red stems and giant leaves all year round
Most of my veges aren't actually perennials, but generous self-seeders. Parsnips, rocket, upland cress, siverbeet, lettuces, salsify, coriander and many more.
You might think about how to "perennialize annuals."
Find some plants that will reseed themselves readily, and you will have them again next year without much work.
But I'm interested in perennial veggies, too.
I love my reseeders - cress, lettuces, dandelions, and most especially CORN SALAD!!! It's the first thing I can eat in the spring (besides dandelions). I'm growing it on top of half my asparagus bed this year - we'll see how it does! I've never had enough corn salad, but perhaps I will this year.
And no one's mentioned purple sprouting broccoli. Is it just especially long lived, or is it perennial? Mine seems to just keep going and going!
Parsley is good for two years in my climate. I follow Bill Mollison's advice and let it go to seed and shake
the seeds out where I want them. I also tried one of his suggestions with peppers and potted a couple and
put them in the garage over winter. Then I plant them back into the garden in spring. I have a pepper plant
that is 3 years old. This gets us eating peppers at least a month earlier than my regular crop. Bill Mollison is
in a different climate but what he says usually works for me.
I like lovage as alternative to celery. And as greens I particularly like nettles.
Also love Egyptian onions as perennial onions, ramps and chives too (and will try to get some multiplier onions as well).
Root-wise, I like yacon (more as a fruit) because it produces so much.
Sunchokes are very productive and strong but still not my adquired taste. But its a practical plant.
I also tried skirret and scorzonoreras, easy to grow and nice taste.
Fruit-wise: most fruit trees are very worth to grow, if you have space and time to wait. Figs come to my mind. Pomegranates too.
Berries are a quick answer, I find raspberries easy to grow and delicious. No worries with it. Strawberries (the wild type) are also another practical plant: grow quick, make a ground cover and delicious fruits.
Herb-wise: I like making peppermint tea, and cooking with marjoram.
in Portugal, sheltered terraces facing eastwards, high water table, uphill original forest of pines, oaks and chestnuts. 2000m2
in Iceland: converted flat lawn, compacted poor soil, cold, windy, humid climate, cold, short summer. 50m2