Herb gardeners are not the kind of people who give up easily. A few years ago, when I nursed my garden through a drought with heavy water (the type carried by hand), I learned the value of special planting techniques borrowed from the native people of the arid Southwest, and gained a new appreciation for the natural drought tolerance of lavender, rosemary and other Mediterranean herbs.
Those of us who grow herbs have a big advantage when it comes to water-wise gardening because we have so many beautiful drought-tolerant choices available to us.
By combining herbs that thrive under dry conditions with several time-tested strategies for reducing moisture loss, you easily can grow an herb garden that requires little or no supplemental water
Strategy # 1: Create Moisture Zones
In water-strapped communities across the country, gardeners have found that placing plants that share similar moisture needs together makes watering more effective and convenient. For example, you might place St. John’s wort, lovage, marshmallow and other herbs that prefer moist soil together in a spot shaded from hot afternoon sun. Should the rain clouds disappear for weeks at a time, you can efficiently water the heavy drinkers until they are satisfied. In similar fashion, herbs that need little water, such as horehound, santolina and all succulents, can be grouped together in hot spots that are difficult to water.
Strategy #2: Support Water-Seeking Roots
Newly planted herbs need moist soil until they establish a functioning network of roots. But after a few weeks, you can fine-tune your watering practices to push plants to develop bigger, better root systems.
Covering the soil’s surface with any type of mulch will block weeds and slow evaporative moisture loss, but there’s a catch. In dry weather, hurried watering sessions that moisten only the mulch and top inch or so of soil encourage plants to develop roots close to the surface, where they quickly dry out. Weekly deep watering, on the other hand, encourages the growth of deeper water-seeking roots.
Using drip or soaker hoses for several hours (or overnight) is the easiest way to deeply water established herbs. Or let water run freely from a hose laid on the ground as you do other things nearby. Avoid using sprinklers, which are inefficient and must be left on for a long time to soak roots deeply.
Strategy # 3: Take a Lesson from the Past
Few places are as hot and dry as the desert southwest, where Zuni gardeners developed an ingenious method called waffle gardening. As the gardeners dug the planting beds, they shaped them into squares or rectangles. Within each one, the Zunis used their hands to mound soil into a waffle pattern. Like warm syrup in a waffle, water collects in each basin when it rains. Between rains, the berms shelter roots from drying sun and wind.
Most gardens receive more rain than Zuni gardens do, but you can adapt the waffle garden concept for your temperate-climate herb garden. In the "Bountiful Water-Wise Bed" shown on Page 30, a berm broad enough to support lavender, sedum and six other herbs shelters the bed’s moist middle, where a soaker hose stands ready to provide water to big, heat-seeking herbs. The bed’s most accessible area is reserved for a select collection of culinary herbs. Within minutes, your herbs can be gathered, watered or both!