Did you know you can use rocks in your garden to increase your garden zone rating? Planting a Zone 3 or even Zone 4 tree next to a massive boulder can be a successful use of rocks in our zone 2b or not 2b gardens. The rock will absorb heat during those late spring and early fall days and release it at night, meaning those early and late frosts can be outsmarted.
In the winter the rock absorbs the cold, helping to keep the area cooler during an untimely chinook. Constant freezing and thawing can be deadly to less hardy trees, shrubs and perennials. A big rock will help keep the temperature from fluctuating. It will also delay the plant from emerging too early in the spring, by “holding its coldness”.