Hi,
My question concerns: how long a perennial wildflower might endure for, if managed (i.e. dug up, through root division, root-pruned, etc.) -- and of the need for genetic diversity when you are trying to have healthy populations of a number of perennials situated in the home landscape.

I have a small property but the intention of growing a large number of native perennial wildflowers -- in many cases, species that are not indigenous to my local region, so I cannot rely on local populations for cross-pollination.

My plan, so far, is to plant the seeds of a variety of native wildflowers that are locally common (seeds being gathered from my region) for 90% of my yard. This way, if I have about 20 parent generation plants of each species, there might be enough potential for genetic diversity and a healthy, persistent population might endure on my property for a lifetime, since cross pollination will occur between the 20 parent plants, their subsequent offspring, and also between those in the vicinity, in some cases just a mile away from my house.

As for the other 10% of the yard, I think I should just grow one single plant per species. In this case, I would not rely on keeping the species sustained through seed propagation, but through relocating and cuttings/vegetative propagation. UNLESS... could I have a healthy population (i.e. no significant inbreeding effects; foundling effect) from 20 parent individuals that are derived from a diverse single population sharing the same ecotype?

The reason I'm concerned it that when you have a naturalized wildflower garden -- one where trees and shrubs are developing and sometimes being removed/pruned, some areas of the yard become less hospitable for certain species, and more hospitable for others, so it can become a dynamic situation over the course of decades. I'd like the wildflowers to persist in a self-sustained way, ideally, which means through seeding themselves. So in cases where there are no nearby populations of a species, If 20 plants per species is too few for a healthy population sustained through cross pollination/seed propagation, I'd rather just stick with a solution of 1 plant per species sustained through hands-on management.

Thanks,
Steve