While it may seem like a rockery is the ideal solution for a rough patch of ground on your property, it requires a lot of work to keep the weeds out. Typically, alpine plants or slow-growing plants that require little water are the choice vegetation for a rockery. Once these plants establish their root system, they need little maintenance. Limiting the number of weeds in the rockery while the alpine plants are establishing themselves greatly enhances the success of the rockery.
Select a location that receives lots of sun and that has good drainage. View the potential site of your rock garden from a typical viewing point of your garden to help you get a perspective on how large to make the rockery and where to set various plants. Sketch the location and indicate where you plan to set specific plants.
Spray an all-purpose weed killer containing glyphosphate, such as Roundup, on the rockery. Depending on the product you choose, you may need to mix it with water and use a garden sprayer. Other products have their own spray dispenser. Follow package directions carefully. Allow three weeks for all the weeds to die before proceeding.
Set jagged-edged stones around the perimeter of the rockery. Use a shovel to set some of the stones in the ground. Leave others sitting on the surface. Make the edge appear as natural as possible.
Provide ample drainage for the alpine plants. If the soil doesn't drain well naturally, dig out at least 15 cm (6 inches) of it. Replace the excavated soil with a mix of larger stones. Add a 10 cm (4 inch) top layer that consists of three parts topsoil and two parts rough, angular limestone chips. Place the topsoil in uneven mounds rather than as a level surface.
Set the plants in the topsoil according to your plan. Keep in mind when the various plants bloom so you have a variety of blooms throughout the growing season. Don't limit yourself to flowering plants. Add in some small conifers and shrubs for variety.
Water the newly set plants lightly. Since most alpine plants prefer to have dry roots, only water the plants during prolonged hot, dry spells. With a rockery, it's more important to weed than to water.
For ease in mixing the topsoil, use a cement mixer. Some alpine plants you may choose to add seasonal colour to your rockery include Anemone blanda, snowdrops, bluebells, dwarf daffodils, dwarf tulips, rock cress, trailing aubrietia, mossy saxifrage, soapwort, rock roses and creeping thyme.