Greenhouse "forest garden" plant suggestions

My tiny greenhouse extends my growing season by a month or two on either end. I want to turn it into a mini food forest. Predatory wasps, ladybugs and spiders have already made themselves at home, so I know there's something for them to eat. That's fine with me, it's a step toward a living ecosystem.

The problem is, what to plant? I already have various greens and herbs naturalizing in there. I don't think there would be room for a tree or a grapevine, even a small one. So I'd like suggestions for perennial plants I could use, with the codicil that everything be edible, and suitable for zone 8. There will be some flowers as well, as food for the predators.

Additional information: Outside dimension 9x11, passive temperature control. The lowest temperature recorded inside this winter was 20 degrees (26 last year), it pretty much stuck between 40 and 25 for most of the season. This means we have an effective zone 8, possibly up to zone 9. I'm planning on zone 8. Effective last frost date would be March 1st based on last year's measurements (last time the temps dropped below freezing was mid February) giving me a 10 month growing season.

I have no idea if they taste good but I have pomegranates and Chilean guava on my list of smaller trees that can handle down to 10F or so.  Maybe olives?  Figs would likely work but may get too big?

Chilean guava tastes good to me; it's distinctively clove-like in flavour but the seeds are crunchy. Some people are meh, some LOVE it.

It smells AMAZING, like cotton candy.



A fig could be kept very small with root pruning. I will keep a fig or three in a theoretical future greenhouse to back up outdoor higher risk figs...

A Meyer lemon could also be kept quite small.