I just love Ajuga but I've killed it all over my garden. I have lived here fourteen years and have added compost to my clay soils almost every year but it keeps fading away to nothing. I've tried many different cultivars and different sizes of pots too.
Other ground covers grow well, some too well. I'd like some well behaved ground covers that tolerate partial shade between shrubs and perennials that won't swamp smaller hostas and ferns and heucheras.
Lily of the valley and sweet woodruff both are too aggressive and have outcompeted many. I wish I'd never planted them. Getting to that point with blue star creeper too. It climbs up into my heathers and dwarf conifers and shades them out.
How's the drainage? IME, ajuga is an extremely easy plant to grow and tolerant of both sun and part shade with reasonable moisture but doesn't care for soggy or very heavy soils. Lamium is an excellent and very well behaved groundcover for me for shade as well - I've found nothing finicky about it. Other choices could include Veronica peduncularis 'Georgia Blue' or Cotula (NZ brass buttons). Or for a very low GC, Corsican mint or baby tears but both of those need moisture and can come and go a bit. Green carpet or Herniaria glabra will also take quite a lot of shade but it is also very low (mat-like) and slow to spread.
When we bought the house fourteen years ago there were no flower beds, just lawn. We've been adding compost to the beds we put in the first year, every year but it is still Willamette Valley clay. I have probably planted over fifty pots of Ajuga of various cultivars. It all fades away to nothing except in one area which is actually one that is more clay than others as it has so many tree roots we can till.
I have some Lamium but slugs and earwigs get it really badly and the bright silver color is a bit much for all over the yard.
I'm ripping out brass buttons today, won't grow where I want but does grow where I don't want. Corsican mint keeps dying out then coming back then dying out then coming back.
I really think it's not you but our climate - it's just too damp for ajuga...but maybe I'm wrong, since gardengal has a different experience. I'm about to plant some haircap moss - would that work for you? or pachysandra?
Ajuga spreads like a weed for me, except for A. Chocolate chips. It doesn't stop grass though and likes to make big clumps or grow into places where I don't want it. I'm wondering if the perfect groundcover exists. Acaena inermis 'Purpurea' is very pretty and spread well, doesn't make the barbed seed heads of the blue-green form, Acaena saccaticulpula Blue Haze. Both of these stay low and don't seem to die out like the other low ground covers I've tried. I find if I put some small rocks in the Corsican Mint it provides a moist microclimate that keeps it from dying out.
My latest attempt is Dymondia margaretae. I just planted it so I'll have to see how it does. I'm also trying Vinca minor in a bed in the sun to see if it will survive as it stays low and looks good all the time.
