Let’s get ready to rock
ROCKERIES have had their ups and downs, horticulturally speaking. In Victorian times, you’d have been talking about half an acre of crags with hardly a plant in sight.
Things went downhill after that and by the 1950s a rockery was a handy way to get rid of your rubble by piling it in a heap on the lawn and hiding it with aubretia.
Then along came a bright idea that changed the face of rock gardening: compact features such as scree gardens, raised beds and stone troughs.
They made an attractive, yet practical, low-maintenance way of growing alpines in small gardens.
The rules for growing rock plants are simple.You need a sunny spot with exceptionally good drainage and absolutely no perennial weeds.
If you’re planning a raised bed, start by building a retaining wall round the edge, at least a foot tall. For a rock garden in a container, I think stone or wood look best, but take your pick.
If your ground is naturally well-drained, you could sink a scree bed into the ground.
Mark out the shape, strip off the turf and remove the soil to a depth of a foot.Then spread a good layer of coarse drainage material over the base. Use builders’ rubble, hardcore or broken bricks for a largish bed, and gravel for a small bed or a container.
Put an inch or two of finer material over this, then top up with a home-made rock-plant compost made by mixing equal parts of good topsoil, horticultural sand and leaf mould or a peat-free potting compost, which is the best bagged alternative.
It sounds like a lot of fuss but it’s worth it.You’ll only do it once, so you might as well do it right.
IT’S NOT essential to have any rocks in a rock feature but if you do, place them next. One decent chunk with a matching smaller one nearby looks much better than lots of little lumps dotted around, which looks as if a child has been throwing stones.
Now you’re ready for some plants.
Most garden centres stock a good range of rock plants, but if you really want to see what’s available, ask a specialist alpine plant nursery.
Don’t just go for what’s in flower at that moment; choose a mixture of plants to provide colour and interest all year round.
Look for contrasting shapes, foliage textures and sizes – but avoid so-called dwarf conifers that aren’t.
If you want a conifer, check its vital statistics to make sure that it’s a genuine miniature.
When your plants arrive, stand them – in their pots – in position on your prepared rock garden, so you can see how they look together.
Try arranging plants in groups of three – one upright, one mound and one mat-shape.
Once you like the layout, tip the plant out of its pot and plant it, leaving the top of each root ball standing about half an inch above ground.When you’ve planted them, spread a layer of stone chippings over the surface so you just cover the top of each root ball.
Besides looking good, a stone mulch is good for the plants because it lets air circulate under low foliage and improves the surface drainage so that they are less likely to rot in wet weather.
And it also stops them from being splashed by mud, too.
The satisfying thing about planting a rock feature like this is that it looks finished straight away.
And do water a rock feature if there’s a long dry spell.
People imagine that because rock plants need good drainage, they are like cacti and can go for years without water – well, it’s a myth, they can’t.
It rains even in the mountains.