It sounds as though you are doing everything right - not overdoing the miracle grow, are you? Problems with baskets usually mean they have dried out at some point - this can happen in a few hours in strong sun and wind. Once dry, water will then run off the surface and not penetrate the compost, so take them down and plunge them into a tub of water to re-hydrate.
Did you go away for a few days and let someone else 'water' them? Compare other aspects such as location, compost, types of plants, etc. My money is on drying out at some point!