Feeding poor-soil loving plants in pots?

Hi - I have got several plants that traditionally prefer poorer soil which are growing in pots, e.g. scabious, lavender, sedum, snow in summer, fleabane etc.  Just wondering if these should ever be fed.  I know that planted in the garden the advice is not to feed them, but as they are in pots and have been for a couple of years, there really won't be any nutrients left in the soil now so I want to give them a flower/fruit feed.  Any thoughts on whether this is the right thing to do please?  Thanks  

Yes, you can give them a feed. Two or three times a year will be fine - much more and you'll get leaves at the expense of flowers.

A couple of extra points.... the reason why wild flowers, when grown in meadows, demand poor soil is that if the soil does have nutrients in it, then grass will grow more vigourously and suffocate the flowers. I can't see why wild flowers should actually prefer no nutrients.

And I'm not certain about this, it's speculation... when grown in open soil (rather than a pot), plants will have contact with soil bacteria and fungi, and this may help to supply them with nutrients. Plants grown in a pot will not have access to the same fungi.

You've also posted another question asking about nitrogen and potash. It's a closely related question. All organisms require nitrogen, and in a natural envionment, this will be fixed by soil bacteria and fungi, sometimes living in, surprisingly, such things as ants nests.

Simply chuckling a handful of fertiliser pellets onto the soil surface does not have the same effect on a plant as mycorrhizal fungi.

TV programs such as Gardeners World could do an awful lot more to educate gardeners about questions like these. Most of us simply don't know what goes on beneath the soil.

Thanks Alina and Gary, I appreciate the answers.  Gary - I totally agree, it is very hard to find information on how to keep your soil naturally fertile.  I also wish that programmes like Gardeners' World were more informative, although the BBC have put pressure on Monty Don to actively promote fungicides and pesticides and he has stood firm and said that he will only promote organic methods, so perhaps that is the best we can hope for for now: http://www.telegraph.co.uk/culture/tvandradio/bbc/9292402/Monty-Don-in-row-with-BBC-over-pledge-he-will-promote-non-organic-gardening.html. I have used mycorrhizal fungi before when planting plants - do you think it might be worth giving the garden a sprinkle of that too when doing the autumn and spring chicken manure feed perhaps?  Thanks