Growing Rock Gardens in Zone 5
When you think rock garden, alpine plants seem to come to mind. This is because the natural rocky outcrops in mountains and hillsides sport native plants that hug the rocks and soften their rugged rigidity. Alpine plants are also highly adaptable to a wide range of conditions and provide maximum performance with minimum output. However, there are many perennial rock garden plants for zone 5 with similar appeal and ease of care. Step away from your rockery and envision the appearance you are trying to achieve while taking consideration to items like exposure, soil type, drainage, and color scheme. United States Department of Agriculture zone 5 can get down to -10 to -20 degrees F. (-23 to -29 C.). These cold temperatures can really affect tender plants, which should be treated as annuals in these climates. Zone 5 rock gardens are especially affected when cold seeps into rocks in winter, creating a chilly footing for plants. In summer, rocks heat up, making cozy and sometimes downright hot conditions. This means that plants in zone 5 must be able to withstand punishing extremes. Select plants that are not only hardy to zone 5 but are adaptable to drought, heat, and freezing.
Selecting Hardy Rock Garden Plants
Consider the exposure the plants will be receiving. Often, a rockery may be mounded and have different exposures and durations of sun on each side. It is important to note this and choose plants accordingly for best results. Low or cascading plants are ideal for a rockery where they decorate and accent the rocks. Some classic examples of rock garden plants for zone 5 that grow 6 to 18 inches (15-46 cm.) in height and produce a color display in spring or early summer are:
Rock cress Candytuft Sedum (creeping varieties) Thrift Alyssum Snow in summer Mountain avens Ice plant
Ground huggers that make nice tidy carpets as they flow over the rockery are easy to care for and have long lasting appeal. Some suggestions include:
Creeping thyme Creeping phlox Blue star creeper Woolly thyme Dwarf yarrow Ajuga Soapwort
Cascading and rock hugging plants are useful for a tight and compact display that shows off the rocks rather than covering them completely. Plants that grow a bit taller and have more extreme profiles are also useful additions to the rockery. These hardy rock garden plants should share the same conditions as their lower growing cousins and only be used in amounts sufficient to add dimension to the garden without covering up all the lower specimens. Ornamental grasses thrive in rockery conditions. Blue fescue and whitlow grass are two plants that will perform well in a rock garden setting in zone 5. Other plants that will give the whole rockery year-round appeal with color and texture include:
Wood anemone Sea holly Tickseed Purple wood spurge Pasque flower Jacob’s ladder Heuchera Heather/heath Rhododendrons and azaleas (dwarf) Dwarf conifers Early spring bulbs
For a decided alpine touch, add mosses and dot the area with plants such as maidenhair or Japanese painted ferns.
