Is your soil actually alkaline or just not very acid? Mine does OK in pH 6.5 but I give it some sequestered iron or an ericaceous feed occasionally (say once or twice a year) if i think abut it.

If your soil is actually alkaline you could pot it in a larger pot or you could prepare a planting station as you would for blueberries by digging out quite a large hole and replacing the soil with ericaceous compost. Feed with ericaceous feed several times through the growing season and mulch with pine needles, coffee grounds, peat or anything acidic. I believe adding sulphur chips helps too but haven't tried that.

Changing soil to acid isn't permanent. If you don't know how acid it is buy yourself a pH metre to check with every now and again.

I am glad I put some plants into pots. A la Chelsea -
am finding that I can move them in midsummer to a new
location where I should have put them in the first place.
Just dig out the soil the right size, drop them in, give them a drink, and its problem solved.
Instant flower arranging in the garden.