A reader has asked if campanulas can grow  in an old half-barrel that already contains a mix of ericaceous soil and topsoil. Many campanula varieties are surprisingly adaptable and aren’t as particular about soil pH as some other plants. While they generally prefer a neutral to slightly alkaline environment (pH 6.0-8.0), they can often tolerate mildly acidic conditions without much fuss. The most critical factor for their success, far more so than a specific pH, is excellent drainage. Before planting, ensure the half-barrel has ample drainage holes at the bottom; if not, you’ll need to add some to prevent the roots from sitting in water, which is a sure way to cause rot.

Given that the barrel already contains a mix, you’re off to a good start. The topsoil will provide a good base of nutrients, and while the ericaceous component will lower the pH, it’s unlikely to be detrimental unless it’s a very high proportion of the mix. To give your campanulas the best chance, consider working in some well-rotted compost or a general-purpose potting mix into the existing soil. This will improve overall fertility, enhance drainage further, and provide a good growing medium. After planting, monitor your campanulas. If they show signs of stress like yellowing leaves (which can sometimes indicate nutrient deficiencies in overly acidic conditions), you might consider a very light application of an all-purpose, balanced liquid feed, but often, they’ll thrive without extra fuss in a well-drained, enriched soil.