According to Peter D'Amato's The Savage Garden, 'Almost all species (sundews) thrive in a mixture of roughly half peat to half sand. Some will require a sandier mix than others. A few do best in long-fibered sphagnum'
Sand is actually very moisture retentive. This is why many succulent growers stay far away form sand.
He recommends your recipe of 2:1:1 for temperate pings.
