I used to ridicule gardeners who used soil in pots. Now I do it too, almost all the time. There are very good reasons NOT to use garden soil – it is full of weed seed, weed root, pests and disease. Worse, soil in a container does not behave like it does in the ground. It will usually hold too much water in proportion to air. It will have insufficient nutrients and clay soils will crack when dry.
|Pots in the courtyard
My Seaton Ross soil is unusual and is almost pure sand. Sandy soils are not usually water retentive. Mine, because the sand has very fine grain, is both water retentive and aerated. This is indeed a stroke of luck. Very few gardeners share such a suitable soil. So the bad news is, I really cannot recommend use of soil in seed trays and small pots without a lot of provisos!
Now the good news! What if you want to fill large tubs and planters? Your soil might just be suitable, especially if it naturally contains plenty of organic matter. You will have to mix in fertilizer and, perhaps, lime. I add dolomitic limestone and a ‘coated’ slow release fertilizer such as osmocote. Limestone or chalk are alternative forms of lime. The hydrated lime sold at garden centres is probably too soluble.
Mixing my soil compost is another reason for the no dig gardener to use his beloved spade!
|These pots are the right sort of depth to be suitable
for a soil compost
Many gardeners do not realise that growers’ suppliers will usually also sell to amateur gardeners (although they will not usually sell professional pesticides). It is necessary to buy in larger quantities and to know what you want. My dolomitic limestone (called dolodust) comes in a 25kg bag from our local East Riding Horticulture at Newton on Derwent.
My ears are burning - I can hear you saying ‘no wonder he is a no dig gardener, he’s on sand’! The truth is that clay soils benefit much more from no-dig than do sandy soils, which bring their own special problems.