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Description

Narrow leaf milkweed is a robust perennial native to many habitats and conditions across all of California. This easy to grow plant is often part of wildlife gardens and restoration projects where it can be planted from seed to mix with native grasses and wildflowers. It is one of several milkweeds that are well known for their butterfly value, and one that can grow throughout the Inland Empire.

Narrow leaf milkweed will grow to heights of 3-4 ft. and produce green linear leaves during the spring season following winter rains. Ball-shaped flower clusters are comprised of many small white to light pink flowers during the spring months. Following the flowering season, this species can survive with little supplemental moisture; pruning in the fall will remove old growth and prepare the plant for another spring growth cycle.

Water Needs

Narrow leaf milkweed grows well in Inland Empire gardens in areas of full sun and with sustained periodic summer water. 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 and you should make irrigation adjustments based on field observations of growth and character. Spring flowering will be more robust and last longer when irrigation is scheduled for the higher end of the range from March through May.

Irrigation Schedule and Graph

Low Water Use Plants

Irrigation Schedule 1

  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 1x 1x 1x 1x 1x 1x 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" 1" 1" 1" 1" 1" 1" 0" to 2" 0" to 2"

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

 
0"-2"
0"-2"
0"-2"
1"
1"
1"
1"
1"
1"
1"
0"-2"
0"-2"
  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
For more information on how to use this Irrigation Schedule and Graph, click here.

Plant Properties

Plant Type: Perennial
Foliage Character: Evergreen
Habit: Upright, Spreading, Robust, Narrow
Growth Rate: Short-lived, Fast
Height: 3 ft. - 4 ft.
Width: 2 ft. - 3 ft.
Water Needs: Low 1
Foliage Color: Bright green
Flower Color: Pink, White
Flower Season: Spring
Soil Adaptations: Well-draining soil, Sand, Loam
Exposure Adaptations: Heat, All day sun
Function: Wildlife value, Restoration, Residential spaces, Raised planters, Flowering accent plant, California native, Borders, Attracts butterflies, Small spaces

Maintenance

If you plant this plant, you will have caterpillars eating them! Be very happy about this, that is the main reason to plant them! Do not remove caterpillars, who require feeding on this plant, unless you have very young plants that cannot handle the amount of feeding on them that is occurring. Plants may look beaten up from being chomped on, but that is fine. You are providing important butterfly habitat, which is more important than an uneaten looking milkweed flower!

It is very important to cut plants all the way to the ground every year in the late fall! This will re-invigorate the plant, but more importantly, it is necessary to prevent the excessive growth of a disease organism that can negatively affect the monarch butterfly caterpillars that feed on the plants. This is not a native milkweed, and this milkweed does not always naturally go dormant in the winter, like milkweeds in our climate have historically done. Cutting the plants to the ground each year mimics the dormant period and helps control the spread of the disease organisms. If you can find them at local native nurseries, also consider planting our native milkweed, Narrow Leaf Milkweed.

Milkweeds will almost always have many tiny yellow insects growing along the stems and flower buds. These are aphids, but do not worry about them. Milkweeds are usually not negatively impacted by their presence and it would be very difficult to win the fight of trying to keep them off of your milkweeds. You definitely do not want to use any pesticides, but can shoot them off with a stream of water or rub them off of the plant if you feel it is necessary. Aphids are important food for larval lady bugs, so you can also just consider them another form of habitat that growing milkweed brings to your garden (S).

References

Associations

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