PLANT COVERAGE & SIZE
Plant Coverage Value
The Plant Coverage Value in square feet is for each plant at its mature width; it is the value that will be used by Program Administrators to determine the canopy coverage regardless of the size of the plant at the time of planting and/or inspection. NOTE: Tree canopy will not be used to determine the 50% plant coverage requirement for Placer County Water Agency's Lawn Replacement Rebate Program.
Coverage value was determined by multiplying the diameter (mature width) of the plant's canopy by .7854. Example: .7854 x 5 ft. diameter x 5 ft. diameter = 20. Totals under .5, were rounded down to the next whole number. Totals above .5, were rounded up to the next whole number.
Where a plant's width is expressed in a range, for example, 20-30' Wide (W), the middle of the width range was used, which in this example is 25' W.
Shrubs have been grouped into the categories of large, medium, and small based on their mature height.
Shrubs - Large
6 - 15 feet tall at maturity
Shrubs - Medium 4 - 6 feet tall at maturity
Shrubs - Small 4 feet or less at maturity
In addition to grouping plants according to their water requirements (hydrozones), plants within each zone need to have the same solar (sun) requirement.
For example: Plants that have low-water-use requirements and prefer full sun should be grouped together and irrigated on the same valve or zone (a valve separate from other zones). Plants with moderate-water-use requirements and prefer part sun should be grouped together and irrigated on a separate valve or zone.
Based on "The New Sunset Western Garden Book" Climate Zones, which takes into consideration temperature, latitude, elevation, ocean influence, and other factors in determining climate zones. If a Sunset Climate Zone was not available for a plant, the U.S. Department of Agriculture (USDA) Zone, which is based on minimum termperatures, was used and converted to the approximate Sunset Climate Zone.
The letter "Y" in the columns noted as Drought Tolerant, CA Native, Deer Resistant, UC All-Star, and/or Rain Garden indicates that "Yes" that plant may be appropriate for this use or benefit.
Plant Water Requirements
Plant water requirements were obtained from WUCOLS IV, Water Use Classification of Landscape Species, Fourth Edition, CA Department of Water Resources, Regents of the University of California, California Center for Urban Horticulture, 2014, except where noted. Sacramento is in Region 2, the Central Valley.
Cultivars, with some exceptions, may not have been included in WUCOLS because it is presumed that many cultivars have the same water requirements as the species.
Water requirements are given for established plants. Consult nursery/landscape professionals, gardening reference books, and/or reliable resources to understand water requirements for specific plant species, the length of time each plant needs to become established, and the amount of water each plant requires. Generally, a plant is established once it has developed substantial roots in the soil adjacent to the root ball, is two-to-three times its size at time of planting or after two to three growing seasons. Note that trees can require between two and five years to become established. The time of establishment varies among species and based upon soil conditions.
Generally, no supplemental irrigation is required during the rainy season. During unusually dry fall and winter seasons, supplemental irrigation may be needed. All newly installed plants need frequent watering, at least every two to three days during warm temperatures. Even drought-tolerant and low-water-use plants need regular water and monitoring at first to ensure that the soil does not dry out completely and plants are not wilting. After a few weeks, watering may be decreased to two times a week. Water until weather cools and rains begin. Plant water requirements and frequency of supplemental irrigation can vary depending on specific soil type as well as weather and site conditions.
Water Requirement Codes
Description applies to established plants, not newly installed plants.
VL - Very Low
Plants that require deep, supplemental irrigation once a month during the dry season to those that require no additional irrigation once established and during years of average rainfall in the Sacramento region.
L - Low
Plants that require deep, supplemental irrigation every two to three weeks during the dry season, once established.
M - Moderate
Plants that require deep, supplemental irrigation once a week during the dry season, once established.
WUCOLS Not Applicable because plant is not listed in WUCOLS. Water Requirement Code based on resources, references, and horticulturalists' experience.