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Purple three-awn deserves more attention than it gets. This California clumping perennial grass has finely rolled foliage, grows 18-24 in. tall and produces colorful purple flowers and seed inflorescences that grow throughout the summer. The seed stage is when it's most colorful. Foliage and flowers fade and decline during fall transition into dormancy; little trimming is needed to maintain good character from year to year.

Purple three-awn is widely distributed in Southern California as well as northern Mexico and the Great Plains states. It is a robust plant that has caught the eye of horticulturists for its ornamental value in native and exotic landscapes and gardens. It can remain in an evergreen state in mild winter zones throughout the year, otherwise it turns deciduous by late fall and becomes sparse and reduced in size. Purple three-awn does best in sunny locations and does well in containers, along borders and in mass plantings to provide color and texture contrast to trees and shrubs. Some seeds can germinate in irrigated settings but are usually easy to manage.

Water Needs

Purple three-awn is highly adapted to sunny garden locations on well drained soils and with low amounts of supplemental water during summer. The chart shown below provides a recommended baseline guide to the monthly irrigation schedule and volume of supplemental water needed to maintain healthy growth throughout the average year. It should be noted there are several months indicated by an asterisk (*) when winter rains can provide sufficient moisture and irrigation is not needed. The high and low range of moisture indicates it can grow with varying amounts of water; more water throughout the dry season will sustain more vigorous character.

Irrigation Schedule and Graph

Low Water Use Plants

Irrigation Schedule 2

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
Runs per Month 0x to 2x 0x to 2x 0x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 0x to 2x 0x to 2x
Inches per Run 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1"
Inches per Month 0" to 2" 0" to 2" 0" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 0" to 2" 0" to 2"

Range of supplemental summer water: 7"-14"
Range of supplemental winter water: 0"-10"

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
For more information on how to use this Irrigation Schedule and Graph, follow this link.

For information how to calculate your irrigation system’s schedule and precipitation rate, please follow this link.

Plant Properties

Plant Type: Grass, Native
Foliage Character: Drought deciduous
Habit: Clumping
Growth Rate: Fast
Height: 18 in. - 24 in.
Width: 24 in. - 30 in.
Water Needs: Low 2
Foliage Color: Bright green
Flower Color: Purple
Flower Season: Summer
Soil Adaptations: Well-draining soil, Loam, Clay
Exposure Adaptations: Aridity, All day sun
Function: Mass planting, Foliage accent plant, Container plant, California native, Borders, Small spaces


Generally does not need much care. Trim a bit if dried seed heads look bad. Dried seed stalks can also be pulled without trimming. Wear gloves because dried seed heads can be sharp. Its seeds will spread and new plants will come up in irrigated gardens. If this is desired, cut back, if necessary in the fall. If this is not desired, cut back in spring before seeds dry out and become viable. New plants that grow in the garden can be left to grow where they come up, "potted up" and moved elsewhere in the garden or given away, or easily pulled out when small. Dried seeds can get caught in the fur or occasionally ears of pets, so either avoid planting this if that is a concern, or cut back before seeds dry out (D, S).



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