A thoughtfully designed garden may enhance a home. However, it is often subtle things that make a difference in how effectively water is applied to that garden and what happens to that water once it enters the garden.
The compacted, clay soils that are common in many of our local gardens make water management a tricky science for most homeowners. If too much water is applied, or if it's applied too quickly, it simply runs off and into the storm drain. Conversely, if short bursts of water are applied, it fails to penetrate more than an inch or two into these poorly aerated soils.
The simple act of building a home wreaks terrible havoc on a garden's soil. Heavy earth-movers and delivery trucks converge, compacting the ground and squeezing out the important air spaces that plant roots need. That's bad news for water conservation, since most gardeners respond by watering lightly and frequently — a wasteful and inefficient habit; a habit that's also bad for the plants.
To compound matters, we tend to cover large portions of our soil with sidewalks, patios, buildings, driveways, stonework and other paving, With so many impermeable surfaces, precious water from irrigations and rainfall gushes down the driveway and into the street, taking with it fertilizer, chemicals, sediment and a hefty load of environmental pollutants. Storm drains become overloaded, and in the end the fresh water our plants depend upon ends up miles away in an ocean or bay.
Water shortages have been an issue for so long that most people now are trying to do their part by planting drought-tolerant species and watering more carefully. The thirsty green lawn is no longer the suburban prize it once was. Yet permeability in landscaping is just starting to catch on as an appropriate gardening practice. Basically, it means increasing the percentage of landscaped areas with permeable surfaces, preventing rainwater from leaving the site.