Loose materials for more casual spaces. I consider loose materials like crushed rock, gravel and shale (also bark mulch) when I want an informal garden pathway or lounging area. They usually cost less and require less labor than other materials, and you don't have to be a master builder to make them look good. But because these materials can be movable after placement, you'll need to do some maintenance to keep them from wandering off.
Hard materials for more formal areas. On the other hand, hard materials such as flagstone, brick, tile, concrete and lumber lend themselves to more "civilized" applications like patios, decks and entryways. These generally withstand a lot of traffic and can easily be cleaned with a broom, a washing down (preferably not in water-scarce climates) or an electric blower, if that's your tool of choice.
Visual appeal. But we seek more than just utility. The first thing we notice in a garden is its visual appeal and sense of style — not how easily ketchup stains can be vanquished. Take cues from the materials and finishes of your house as well as influences from the natural environment.
Environmental impact. Think about where the materials originated, whether they come from recycled sources and whether they are permeable. If you don't know, ask.
Cost. For most of us, cost is the elephant in the room. The best advice I can offer here is to not be penny wise and pound foolish. I've found time and again that a bit more expense (sometimes a lot) on the front end assures that you've selected the best floor for the job, the one least likely to come back and bite you later.
Stone. Stone is enduring and elemental, taking many forms. Where a naturalistic style is most appropriate, irregular slabs of flagstone edged with dainty ground covers look right at home. In formal dining terraces, geometric shapes solidly mortared to a slab are a practical solution, assuring that the stones stay in place and provide a level surface.
When it comes to selecting the right stone for your project, consider not only the color, but also its surface texture. Too smooth and it might present a slip hazard; too irregular and you'll have a hard time leveling a table (or walking in 6-inch stiletto heels — not a problem for me).
Stability and safety are paramount concerns, so be sure to set the stepping stones on a well-compacted base with some of their mass underground to keep them from tilting and moving around. Check that pathway stones are large enough and ergonomically spaced so you can land on them without having to delicately dance from one to the next.
The color of the stone should harmonize with the exterior of your home, other garden hardscaping and natural elements. You'll find a wide range, from nearly black to gray to white, and browns including rusty oxide-infused shades.
If you're the one responsible for rolling the trash cans from the side yard to the curb every Thursday evening, you'll be happy you passed on a pea gravel path and went with a continuous ribbon of mortared brick.
The color palette for brick requires additional design decisions; colors include a range of nearly black through gray, brown, red and some yellowish tints. Although individual bricks are rectangular, there are endless patterns to experiment with, including traditional running bond, herringbone, basket weave, radial spokes, gentle curves and whimsical layouts that look like someone pounded down one too many beers at lunch.
For shady, moist areas where moss can cause slip-and-fall accidents, be vigilant about choosing materials, like brick, that can withstand a strong blast from a hose or deep scrubbing with a coarse broom.
Caution: Where the ground freezes, loosely set brick can heave, making the path uneven and possibly dangerous. And steer clear of mature trees with surface roots.
But if you’ve got a sloping property, need a level surface for outdoor entertaining and want to avoid the expense and disruption of building retaining walls, decking is the way to go. Since you’re not likely to add on to the deck once it’s built, now is the time to decide how it will be used and make space for all the furnishings you want.
However, these materials are more likely to be displaced, especially if water passes over them. And gritty, sandy materials are the last things you want to track onto your hardwood entryway. One of my favorite design treatments for upgrading crushed rock paths uses enriched thresholds and intersections of stone.
Another consideration is how "at home" a lawn is in your climate. Where rainfall is dependable and plentiful, you needn't be too concerned about using potable water for irrigation. And there are lots of organic approaches to lawn care, so you can avoid the old-school arsenal of chemical sprays and treatments that can be detrimental to beneficial insects, wildlife and groundwater. But in arid climates, more and more people are going lawnless to help conserve water as well as lower their dependence on fossil fuels for mowing and edging.
More: How to Pick a Mulch — and Why Your Soil Wants It