Perennial Irrigation

Age

• Young perennials need evenly moist soil as they develop a strong root system. Newly planted perennials lack deep roots and suffer transplant shock if not watered regularly. Plant perennials in spring or early fall when the soil is moist and temperatures mild. Water them regularly throughout the first growing season until they become established. After the first year or two, perennials become more drought-tolerant, depending on the variety. Watch for signs of drought stress, such as wilting leaves and dropping flowers and increase watering if necessary.

Variety

• Perennials vary widely in the amount of irrigation they need, depending on the plant type. Native wildflowers found in fields, such as daylilies, coneflowers or yarrow, are often tolerant of drought. Those that prefer shaded settings, such as astilbe, bellflower or coralbells, require more water. Gas plant, loosestrife, balloon flower and snakeroot prefer moist, even wet, soil.

Growing Conditions

• How much irrigation perennials need also varies with soil type and climate. Heavy clay soils hold water well and require less frequent watering. Sandy, light soils leach water and need frequent, shallow irrigation. Perennials growing in hot, dry, windy climates need more frequent irrigation than those growing in humid, mild areas.

General Recommendations

• Water perennials early in the morning so water dries quickly. Wet leaves contribute to the spread of disease. Amend the soil with compost or manure before planting perennials to improve drainage. Mulch perennial beds with 3 to 4 inches of wood chip or bark mulch to conserve moisture and regulate soil temperatures. Perennials planted next to irrigated lawns may receive too much water, depending on the plant type. Adjust the sprinkler heads if necessary. Water perennials once a month during the winter during dry conditions.