Initially, you should realise that altering the existing soil condition is not a once-for-all operation, and that the ground will need regular attention to keep it sufficiently acid for the plants to continue to thrive.
Growing acid-loving plants in a chalky or limestone district is difficult, in many cases such plants will fail, partly because of the prevailing soil and partly because the climate is often wrong for them as well. In general, most acid-lovers prefer wet summers and mild winters. Even where favourable conditions exist, the soil will need to be altered radically simply to allow the plants to thrive.
You might think that simply digging out planting holes and filling them with acid material like peat would be the solution. It isn’t, merely a waste of time. Within three or four years at the most, chalky water will have seeped in from the surrounding soil and you’ll be back to square one with plants as yellow as quinces.
If you’re determined on the project, the most successful way will be either raised beds or containers for the plants. The raised-bed system relies on the fact that water flows sideways and downwards, seldom upwards. Start by marking out the growing area, then put wooden planks, bricks or, best of all peat blocks around it to form a wall at least a foot high and, for ease of cultivation, no more than 3ft wide. You can also use large stones or small boulders for the wall, but make sure they are not limestone.
Much the same goes for filling containers for acid-loving plants with lime-free ericaceous compost, but as the operation is on a smaller scale it is less laborious and expensive. Once completed, fill the enclosed area with acid soil – a difficult and expensive task for a large bed.