I would be wary of covering with gravel. I removed mine when it became a nightmare to keep the plants watered when it became really hot in the sun. It's fine if you have desert type planting but anything which needs water like the Tracleospermum wont thrive. I now use bark as a weed suppressant. Currently I'm using up some orchid compost on my pots as I had to buy a large quantity and it would take me ages to use it for my orchids. It's finer than the bark used on borders. Alternatively you could try creeping alpinines like sedum or even sempervivums.
I would be wary of covering with gravel. I removed mine when it became a nightmare to keep the plants watered when it became really hot in the sun. It's fine if you have desert type planting but anything which needs water like the Tracleospermum wont thrive. I now use bark as a weed suppressant. Currently I'm using up some orchid compost on my pots as I had to buy a large quantity and it would take me ages to use it for my orchids. It's finer than the bark used on borders. Alternatively you could try creeping alpinines like sedum or even sempervivums.
The only gravel will be the bottom square with desert plants. The soil/sand mix will be at least 20cm deep. I've already got my eye on a clump of sempervivum in my folk's garden.
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