What kind of stone should you choose?
• Limestone cut into rectangles (rundle rock, quarried in Canmore, Alta., for example) or split into flagstones is easy to work with. Sandstone and shale are also relatively flat and simple to use for beginners. Round or irregular granite boulders are extremely durable but harder to place and secure.

• Choose carefully -- stonework should belong in its surroundings. Locally quarried rock, if available, naturally looks at home.

• Match the scale of the rocks to the scale of your house and garden: for instance, large, round boulders or craggy, irregular stones can overpower a tidy bungalow with a neat garden. Also match the style: low flagstone walls may best accentuate the horizontal lines of a long ranch-style house, for example.

• You may also marry stone to plants. Use granite boulders to border a bed of acid-loving plants such as ferns and heather and mulch the bed with granite pea gravel. For lime-loving plants such as gypsophila and sempervivum, use limestone for the wall and mulch with limestone scree (small, sharp chips). Tufa, a porous, weathered limestone can be used to hold tiny plants in its cracks and pockets. (Most perennials and dwarf conifers will thrive alongside either rock type.)

How you stack up
• Wear sturdy shoes and gloves and be prepared for heavy lifting. Begin by sorting stone according to size so it's easy to find what you need as you build. Sort out any stones with curved or right-angled edges to use where wall turns a corner.

• Next, use strings and stakes to mark the footprint of your planned wall on the ground; inside it, dig a trench deep enough (dig down 25.5 cm/10 in or to bedrock or hardpan, whichever comes first) and wide enough for the first course (layer) of stones, the “grounders” (these biggest, flattest rocks will sit entirely below ground). Lay the grounders, edges tight together and broadside down. Use a 2-ft carpenter's level to check the base of the trench (and as you work, to check that each course of stones is as level as possible when using irregular fieldstone).

• Continue building the wall, one course at a time. For strength, bridge the vertical cracks in the course below (think of a brick wall). If necessary, shim cracks between courses with stone chips (don't use soil; it can promote frost heave).

• Gradually slope the wall inward (toward planned bed) as you build upward, about 2.5 cm (1 in) for every 30.5 cm (12 in) up, using smaller stones for each course, then lay a final course of capstones that extend into the bed approx 15 cm (6 in).

Page 2 of 3