Green Driveway

How would you like a lawn so tough that you can drive a car or truck on it? That's what homeowner Art Giz got when he worked with landscape architect Terry Camp to create a park-like setting where there used to be a concrete driveway. The result was reclaimed space perfect for leisure and play that formerly was used only for parked cars.

In this case the green driveway went beside and behind the house. It connects two aprons of concrete (which have been professionally poured) and is indistinguishable from the grassy areas around it.

The cost of the project if done professionally would be approximately $3,100, which includes $750 for an irrigation system and another $2,400 to install the grass pavers and driveway. With the homeowner doing the bulk of the work himself, however, the cost can be reduced to $1,200. On a difficulty scale of 1 to 4, Camp rates the project a 4 because of the grading and trench-digging involved for the irrigation system.

First, check the pitch of the existing site. If it's too flat, water will lie in puddles on your lawn. The goal is to steer water away from the foundation of your house and toward a drain that will carry it out of the yard.

Figuring out the grade of the slope is not too difficult. Place a long level on a two-by-four, and read the level. Camp recommends a 1 percent pitch--that is, a quarter-inch bead drop on the level. That way the slope doesn't feel steep, but it's sharp enough for rain to run off. If the site doesn't have enough drop, dig out some soil and move it to another area of the yard or garden. At the lowest spot in the green driveway, place a simple catch basin and drain (figure A), available at any hardware store. This drain connects to an underground pipe that will empty into the street when it rains.

Step Two: Preparing the Ground

At this point, if the driveway is not constructed properly, you could end up with potholes, just like the usual ones on roads and highways.

Lightweight plastic grass pavers are the "secret ingredient" of this project (figure C). The interlocking pavers cost about $1.20 per square foot and can be purchased at stores where irrigation supplies are sold. Measure the length you need for the driveway and cut the pavers to fit.

Lay the pavers across the width of the driveway rather than lengthwise. Place the pavers down carefully so as not to disturb the prepared road base. Next, fill the cells with coarse concrete sand (figure D). Finally, compact the area again (figure E) with the vibratory plate compactor. Camp recommends that you place, fill and compact one strip of pavers at a time to make sure each piece fits well.

Plantings

Be careful not to overplant, says Camp. The tendency is to get instant gratification from instant planting. Instead, leave plenty of room for plants to grow.

For this project, sturdy, low-maintenance plants that can stand up to high traffic are the best choices for the driveway area. Camp selects shade trees, colorful shrubs and long-blooming perennials including pink breath of heaven (Coleonema pulchrum ), laurustinus (Viburnum tinus 'Spring Bouquet') and flowering pear (Pyrus calleryana 'Aristocrat').

Step Three: Installing the Irrigation

The best way to install irrigation, according to landscape contractor Jean Fogg, is to use a concept called hydro-zoning. Each separate valve controls a separate part of the yard, such as the turf area, the shrub areas and the trees and groundcovers. You can set the timing for each valve individually, saving a surprising amount of water in the process.

For the most water-efficient design, have a professional draw up your irrigation plans. Fogg recommends that you have a professional tap your main water line, then you can install the rest of the components yourself.

Step Four: Rolling out the Sod

When considering the best sod to use for this project, dwarf fescue turf is the "bully on the block," says Fogg. It's drought-tolerant and will stand up well to cars being driven on it. In colder climates, Bermuda turf would be a better choice, he notes.