Primulas for dry shade under trees?

Primula veris (cowslip) which is native here grows in such conditions. They flower in spring (May here) and go dormant in summer.

This deciduous wood is very shady in summer and the topsoil is rather dry. The cowslip even grows in pockets of soil in the bedrock. These pockets often get completely dry in summer. However the temperature seldom exceeds 25C.

I agree, Primula veris can take dry shade.  It will also take black walnut juglones without flinching, in my experience.  I have a P. veris var. macrocalyx colony that I started from seed over twenty years ago, and they have been self-seeding ever since.  They live within five metres of a ten-metre high black walnut (I think within the dripline), so I certainly presume the soil is infested with juglones.  I've transplanted them into other locations, and they always take well.  They flower beautifully in the spring, and then the foliage persists quite well for the rest of the year.  

I would also check Kevin Baker's Edmonton, Alberta garden, and see if any of his Primulas are growing in dry shade.  His blog is "The Plants I Grow", on wordpress.com.  He also sells seeds of many of his plants, so you know they'll be hardy!  

Alison

Zone 5a, Ottawa, Ontario

I had Primula sikkimensis and P. alpicola growing for many years in the shade of trees in this naturally dry area.  P. rosea also did surprisingly well, given it's normal habitat (wet conditions).  I'm told that primroses, in general, need to be propagated to continue beyond the first number of years, which I did not bother to do. 

P. elatior, P. veris, P. polyneura, P. cortusoides, and various P. marginata  and P. juliae hybrids/cultivars have survived and done well in these conditions for many years here also, with self-seeding and/or decent vegetative spreading.

So, other than eventual losses due to my own laziness, I've found that some of the tougher primroses can do quite satisfactorily in what would seem to be much less than optimum conditions.

I grow Primula cusickiana in semishade under pine trees. Where these plants are sited it is moderatly moist in the spring and almost bane dry all summer. If the soil is moist in the summer when this plant is dormant it will go into permanent dormancy.