A Dry Streambed

Kahlstrom estimates that a professional would charge about $1,000 to design and install a streambed, but do-it-yourselfers can buy the stones and plants for about $250. This project is rated an easy 2 on a difficulty scale of 1 (easy) to 5 (difficult) and can be completed in one weekend.

Step One: Defining the Course

The site already has a natural grade leading away from the patio towards the side yard, which will help to funnel water to that area. This streambed will be 16 feet long.

Use a shovel to carve out the ditch, with the sides being concave rather than straight down. Gradually increase the depth from the sides to nine inches in the middle.

Step Two: Lining the Ditch

Landscape fabric, available for about $20 a roll, prevents weeds and helps hold the shape of the streambed. Cut one continuous piece of landscape fabric to the length and width of the streambed. Lay it in the bed and secure it with landscape staples or irrigation stakes. Smooth it out as you go to keep it taut. Pleat the fabric to shape it around curves.

Step Three: Placing the Boulders

Kahlstrom offers two key tips for creating a natural-looking streambed.

• Vary the sizes of rocks and boulders to mimic nature.
• Place bigger stones on the outer banks and medium and smaller stones towards the center.

Estimate where the stepping stones will go, marking out the distance of a normal stride, about 18 inches. Stagger the stones so that they don't line up too perfectly. After determining the placement, dig out a shallow trough underneath each one, and place them flat side up. Pack soil around the stones to keep them stabilized.

Create groupings of rocks along the outer edge, especially in the bends of the curves. Fill in along the edge with smaller rocks, placed randomly.

Step Four: Completing the Dry Stream

Use a hose to mist the streambed to push the clumps of sand into any gaps and around the stones so they'll appear to be embedded in the sand.

Planting: A Dry Streambed

Plants help to integrate the dry streambed with the surrounding landscaping. They also soften the edges and provide year-round color and interest. Kahlstrom recommends selecting plants that naturally occur along streams; he chose an assortment of grasses, lacy ferns, tall brushes, and flowering plants, including:

• Cape rush (Chondropetalum tectorum), Zones 9-10
• Phormium tenax 'Dark Delight', Zones 9-10
• Autumn fern (Dryopteris erythrosora), Zones 6-9