Daylilies (Hemerocalis fulva) are edge plants, growing on the edges of woods and roads, looking like a grass but not quite, sitting on the edge of good ground cover standards.
They grow in massive colonies along the roads, but don’t entirely exclude grass. If they did, they are a little too tall to plant most perennial vegetables between.
At the same time, they are a perennial vegetable themselves. In their home country of China, daylilies are prized for their buds and second day dried flowers called ‘golden needles.’
For me they’re easily available. If the roadcrew digs out the roadside ditches they are already dug for me. I just steal the big clumps to take home and divide.
Easily available and easily grown you could just throw them on the edges of the food forest and harvest the flowers not giving a care about what grows between them. They don’t care.
They can exclude grass if you stick vines among them. It’s the perfect match because daylily stems make excellent trellises.
The perennial sweetpea (Lathyrus latifolius) is one of my favorites for this because the pink sweet pea just screams next to the orange daylily.
The near relation, Lathyrus tuberosum, does the same. Since it runs more, it fills the cracks even better, although you’d have to dig to get the edible tubers.
I’ve heard of sticking groundnuts (Apios americana) between daylilies too, which also have edible tubers and pink flowers. So pick your shade of pink and flavor of root. All three of the above fix nitrogen.
But digging doesn’t seem practical to me. You’ll get a yield if you choose above ground producing vines, like cinamon vine (Dioscorea batatas) which produces many little potatoes on the leaf axils, or woody vines like akebia (Akebia quinata) which provides fruit, and would smother all, settling down to the ground over winter making a truly impermeable mat.
Don’t worry about it shading out the dayliles. The final straw that made me add them to this list is their tolerance for shade.
I consider this a highly valuable trait in groundcovers because, like violets, you can smother out the sunloving weeds with mulch and not worry about harming your prefered crop. When the mulch is gone, so are the weeds. All that’s left is a lush groundcover.
Daylilies will grow large patches in the deep shade of woods. Just don’t expect flowers, they need sun for that.
There are many other species of Hemerocalis. I consider most of these clump formers so give a groundcover like mint to grow among them. It’s Hem. fulva that covers so much ground and needs special attention.