Euphorbia squarrosa follows a summer-rainfall pattern typical of the Eastern Cape. It begins active growth in late spring, producing new stems and small cyathia from the apex of its caudex throughout the summer months. It is highly opportunistic and will continue to grow as long as warmth and moisture are present. It enters a semi-dormancy in the dry winter. During this time, the plant should be kept mostly dry. In cultivation, it is often grown with the caudex "raised" for aesthetic reasons, but this exposes the sensitive rootstock to temperature fluctuations it wouldn't face underground. To protect the plant, use a very porous, mineral-heavy substrate—such as 80% pumice and 20% organic matter—to ensure the caudex dries quickly after watering and never sits in soggy soil.