Each new year provides a chance to transform difficult areas in your landscape into something beautiful. I have an area that has not sustained plant growth for more than a growing season. This year my garden plan is to develop a rock garden in this spot. This should be easy, as rocks do not take any water, are not fussy about soil tilth and are consistent for all seasons. After some research I discovered the beautiful and delicate flowers that make rock gardens look so spectacular require thoughtful selection, care and careful planning.
The first decision to be made is where to place a rock garden. Since most rock garden plants require excellent drainage, a natural slope is the perfect place for a rock garden. And while rocks don't require water, the plants around them do; access to water is vital. Plan on how you will irrigate the garden and how the rocks will affect the drainage flow.
The next task is to choose and add the rocks. A rock garden is meant to recreate nature, which is not perfect or symmetrical. Choose rocks of the same geological type but of various sizes and shapes to give the garden interesting dimensions and textures. Be sure to include some large rocks and be careful not to space the rocks too evenly. To mimic nature, rocks should be set into the ground with one-third to two-thirds of the rock buried.
When selecting plants for the garden, keep in mind the rocks will create new microclimates. They increase the amount of heat or the amount of coolness around any plant material. A rock garden can be in part shade, but the rocks will retain heat from the partial sun exposure, so the plants will need to be more heat-tolerant that a typical part-shade loving plant. During winter the minimum temperature in a rock garden could be lower than what is reported on a nearby outdoor temperature gauge.
Plant selection includes varieties of small bulbs, shrubs, perennials and, of course, ground covers. Be aware that some aggressive-growing plants can take over a garden and cover up the interesting details of the rocks. Plants suited for rock gardens like full-sun or part-shade conditions, well-draining soil and will require about an inch of water per week.
A comprehensive list of rock garden plants can be found in Fact Sheet 7.401: Rock Garden Plants at ext.colostate.edu/pubs/Garden/07401.html.
A rock garden's naturalistic appearance provides the opportunity to enjoy the contrast of rocks and a wide variety of plant materials in a unique garden setting. Is there a place for one in your landscape?