London Soil Problem Solved By Adding More Organic Matter.
Much of the soil in central London started as a clay loam and then over
a number of years especially in the Victorian period the ash from old
house fires was added to the soil changing the structure to a more open
type of soil.So its a good idea to add spent mushroom compost to your
soil every spring as a mulch, this will help maintain a correct soil pH
as the mushroom compost contains lime and also add humists to the soil.
The exception to this rule is if you are growing some acid loving plants
such as azalea or camellias in which case you should add well rotted
farm yard manure which will help to maintain the acid soil conditions
these plants require.