Yarrow is a perennial plant that's a favorite of gardeners in hot, dry areas. According to the U.S. Department of Agriculture, the species called Western (sometimes wooly) yarrow, Achillea millefolium L. var. Occidentalis, differs from common yarrow in that it's shorter, less invasive and flowers and produces seeds later in the year. The most common color of western yarrow is white.
Plant yarrow where it will get six to eight hours of sunshine every day.
Dig the flower bed, 12 to 15 inches deep.
Spread two to four inches of compost over the spaded-up soil.
Mix the compost into the soil thoroughly.
Smooth the soil out level.
Gently remove the yarrow plants from the pots they came in.
Dig a hole for each plant that's twice as wide as the pot the plant came in. Separate the holes for the plants by a foot.
Put the plant into the hole and fill the hole with dirt so that the roots of the plant are just below the top of the hole. Cover the roots up and lightly press the soil down on them.
Water the plants well the first time, but if water continues to stand on the soil around their roots four or five hours later, don't water them as heavily in the future. Excessive water will rot the plants' roots.
Each week, make sure the plants get about an inch of water, either from rainfall or supplemental irrigation. To check this, put a metal can or a plastic container in your flower bed where the sprinklers will hit it. After you water, or after it's rained, measure how much water is in the bottom of the can with a rigid ruler and keep track throughout the week of how much water your yarrow has gotten. Water as needed to give the plants their necessary inch of irrigation.
Pull up any weeds that emerge in the flower bed immediately.
Every spring, spread out two inches of mulch over the flower bed and push it up against the roots of the plants.