A rock garden makes a wonderful feature and with succulents it will be green all year.
A rock garden should be placed where it will be seen. A corner of the garden is a popular choice. Succulents require good drainage to prosper so choose an elevated position, if possible.
If you live in an area where it is possible to collect rocks, you should start a collection. The size and shapes of the rocks will suggest ideas to you about how to arrange them.
Level or Mounded
Rock gardens can be built on level ground or as hummocks. A 4-feet high hummock should ideally have a base at least 8 feet in diameter. Succulents can be chosen for their low mature height and a hummock will bring them nearer to eye level for more enjoyment.
Succulents will grow in just about any soil that has good drainage. For a level rock garden you will not need to change the soil if the drainage is good but it can be a good idea. Dig out the soil to a depth of 6 inches or more. Place a layer of small rubble over the area and then replace the soil. This will create a slight elevation to the bed and improve the drainage. To make a hummock, use a pile of larger rubble to start with, cover that with smaller rubble and then the soil. Shape the profile to make it more interesting than a simple cone.
A rock garden with large and interestingly shaped rocks can create a rough border around the rock garden. Don’t put the other rocks into place until you have installed the plants.
Use the plants you have chosen to create effects and color highlights. Succulents do flower but only for short periods so it is the color of the foliage that should be considered. Bushier and taller growing succulents (especially some vertical cacti) can be placed near the top or center of the rock garden. Do not place plants very close together.
The Remaining Rocks
Once you have the plants in position you can spend time arranging the rocks to add to the effect. Try to have rocks under some foliage so it looks like the plants grew over them. Even though the plants are separated, use 2 or 3 rocks together in a few places. If you have a variety of rock colors and textures you can create a visually satisfying rock garden.
Building a rock garden is easy. Making it look like a natural feature is not. Avoid the temptation to over-populate it with plants. Don’t try to fill all the spaces between the plants with rocks. The plants will eventually grow naturally to fill gaps. Using a variety of stones in some of the spaces around the plants can add to the effect. A new rock garden takes a while to become more mature and natural looking because the plants grow slowly. Setting the garden up is easy--but you must wait for it to look its natural best.