Thank you!

This is what Territorial Seeds has on their website for Perpetual Spinach

"A tasty and smooth-leafed variety that produces throughout the summer and can bear for several years in zone 7 and higher." Confusing isnt it?

https://territorialseed.com/products/swiss-chard-perpetual

And this guy shows how he divides PS. But of course he is in a very different (hotter) climate from mine.

https://www.youtube.com/watch?v=c3pUre2pars

I am going to grow some and see what happens for me.

I grew New Zealand spinach for several years, due to its supposed heat tolerance - which it has. It is cold tolerant as well, even surviving a couple frosts; so a very tough plant. The seeds can be slow to germinate & are slow-growing initially, so you might want to start them early. Like beets & chard, each "seed" is actually a shell with several seeds inside, so don't be surprised at the number of sprouts which emerge. Those seedlings are thin & weed-like, so be careful not to pull some of them accidentally (as I did). When full grown, NZ spinach is a sprawling, ground-hugging plant, mine were about 3' wide by Autumn. They respond to being cut back by branching more heavily, so you likely wouldn't need many plants.

DW would cut off young shoots with 3-4 leaves, but remove & cook the leaves only. The leaves closely resemble spinach in flavor, with a similar oxalic acid content (I believe the two are related). I would not recommend eating it raw. There is something potentially off-putting about the texture of the leaf surface, reminiscent of Lambs Quarter, if you've ever eaten that. Chard goes all summer long here, so that & water spinach (which is VERY heat tolerant) are the only pot herbs we grow every year now.

Amaranth is another good hot-weather green; if you keep it cut back, it will go almost all Summer. While the leaves of any amaranth are edible (DW & I even harvest wild amaranth occasionally) there are Asian varieties bred specifically for leaf production. BC lists two of those on their website.

This Spring you should check out the local independent nurseries within a half hour drive and see if some of them grow/stock some odd veggie seedlings. You could try different edible plants that way and see what you like, other than trying to get these all to mature growing from seed.

I assume you have thought about Kale, which there are many types to choose, and plants are attractive. Perpetual Spinach is like a chard, and it grows all year long like Kale until the deep cold. Leaves of both could taste better with frosts, then they flower the next year if they survive the Winter.

Perpetual spinach (chard) does become much sweeter when it gets cold. I've never had it survive a winter in zone 5 unless it was planted in a high tunnel. As far as a perennial green, have you thought about Good King Henry? https://www.fedcoseeds.com/seeds/good-king-henry-eco-perennial-green-3096

I grew NZ spinach in my greenhouse. It was indeed perennial in the greenhouse, which get frost every night for a good three months of winter. It would get a bit ragged in the winter but then I'd cut it back in spring and boomed forth again.

Unfortunately I usually disliked the taste. Some people, me included, found some kind of unpleasant metallic taste in it. I dunno, I don't think it's just oxalic acid, because I'm one of those people who can eat bolting spinach, which I know should have lots of oxalic acid. And generally I'm a person who likes to eat all kinds of leafy greens, cooked or raw, including lambsquarters (fat hen), spinach, chard, kale and all brassicas, orach, and all kinds of weird wild foraged greens. But NZ spinach.... not so much.

I found it improved by boiling it in salted water and discarding the water, then sauteing it. Sometimes it tasted fine to me and sometimes unpleasant. I don't think it was the larger leaves that bugged me more. I don't think it having set flowers or seeds made a difference either. I dunno. But some of my friends thought it tasted fine and couldn't taste that metallic flavor when I could.

The seeds do indeed germinate very slowly and irregularly, so it's a good thing it's perennial. And then it self seeds, so after the first year you will get lots of seedlings to spread it out if you like.

It's a bit messy looking the way it sprawls, but the advantage I found was that it got almost no aphids, unlike pretty much all other edible greens in my greenhouse at certain times of year.

Last summer I pulled out the main plant after 4 years. I'll either give up on it, or if some seedlings come up I might give it another go. Being perennial and aphid-free is very convenient, and maybe I'll yet find a way to get rid of the flavor that bothers me...

"I found it improved by boiling it in salted water and discarding the water..."

That was my conclusion as well. I also noticed that although NZ spinach is touted as a hot-weather green, I much preferred its flavor when grown in cooler conditions. Which is not really surprising IMO since I find that cool weather improves the flavor of many vegetables, especially greens.

Interesting to hear that aphids were not attracted to NZ spinach, as they are to real spinach or chard. That could make it worth considering for greenhouse culture, in spite of its less-desirable characteristics.

I found the flavor of New Zealand spinach changed greatly in different parts of the garden. I am in zone 10, so might be warmer than others. Spinach in full sun and sandier soils had more funky aftertastes, but the plants grown with 1-3 hours of shade were more pleasant and smooth tasting. The larger leaves could be chopped and frozen for soup, and the small leaves were very good slightly wilted in eggs.