A couple of years ago I started to turn the floor of the old water mill into a scree bed. Taking the turf off revealed a floor that had once simply been beaten clay with broken brick and tile. So, no drainage. I considered that, with luck, relatively shallow-rooted alpines could grow in gravel above the old floor, and so far this appears to be the case. I’ve used pea gravel to a depth of between four and six inches, not mixed with any soil or compost. When planting, I take a fairly deep plug out of the clay, fill it with gravel, add a handful of compost, and plant to a depth where the neck of the plant will have plenty of gravel round it. Results have been encouraging.
II work at trying to have colour in the scree bed throughout spring and summer. At this time of year, through to August, I rely on the South African rhodohypoxis varieties to give the colour needed to draw the eye. This (I think) is rhodohypoxis ‘Douglas’:
Rhodohypoxis are reliable here in Scotland, but the grassy leaves, followed immediately by the flower buds, push through the gravel quite late in April, so I have to remember where they are when weeding. Luckily, a nursery specialising in them is within range, so I don’t have to buy sight unseen. I note the Alpine garden society recommends covering them with a slate in winter to keep them dry, but I haven’t bothered to do this yet, and so far I haven’t lost any.