I've been experimenting with growing plants as a barrier against invasive grasses that will choke out other plants in my garden. I planted a single row with yarrow, santolina, and artemisia all dense spreading plants with a height that seldom surpasses two feet. I didn't plant them closely enough in the first place for complete grass suppression, but the only failure is between the plants. With those results, I think I need to expand this micro hedge. I started my expansion with more yarrow, perennialflax, and Gregg's mist flower this morning.
While many flowering perennials fit the bill, I don't know which ones could also add to my medicine chest or pantry. I'd like to maximize variety and function while I'm at it. I need recommendations for both part sun and full sun plants that can survive minimal watering in Zone 8b. Evergreen would be prefered, but if it produces enough self mulch material to suppress weeds even during it's dormant phase, that would still work. Lantana is an ornamental example I've seen manage that. Also if you know of uses for what I've already planted, that would be great. Right now, all I'm sure of is that yarrow can help stop bleeding from cuts.
There's a lot of varieties. Theoretically there would be one with the perfect size for me, but for some reason I kill nearly every rosemary I've ever planted. I can keep an eye on the one in the front that has survived, but I think it's going to end up too tall.
An herb like oregano might suit your purpose. I'm in zone 9a also and my oregano is cut down in the fall, it grows back a bit during winter, and as spring arrives it begins to grow quite actively. There is a mound in my garden that is about 12" high and has spread to about 18" --so far. It will spread almost invasively over the growing season. It smothers everything around it.
Another herb, lemon balm has a similar growth habit. During the very hot summer months, both herbs must be kept watered, the only drawback.
I have some oregano in the front, as well as some winter savory that exhibits the characteristics I'm looking for. Maybe I'll transplant some back there. It doesn't help diversify my garden, though.
I am thinking about seeing if I can find a source for the original daylily that is confirmed safe and tasty to eat. I have more decorative varieties in the front. They fight of grass fairly well, but I've heard variable reports on whether they're all safe to eat. I'm also not sure if they'll stay small enough that I can easily reach over them to work the garden bed they edge.
Companion Planting Guide by World Permaculture Association