Which type of John Innes for rock plants?
We are filling in the gap between 2 stone walls (about 18 inches apart) and want to plant the top with rock plants. We will put loads of stones and then grit in the bottom (with drainage holes) but what sort of soil should we mix with grit at the top. Should it be John Innes 1, 2 or John Innes 3? We plan to plant with rock plants - delospermum, armeria, rock roses, saxifrage, lithodora etc. Please tell us what sort of soil mix would be best.