Owl's Clover
Castilleja exserta
Dense spikes of rose-pink to purple blooms paint the desert floor in spring, creating a wildflower spectacle.
A cool-season annual in USDA zones 9-11; early-fall-sown for spring bloom in the low desert, it finishes before summer heat and depends on reseeding to persist.
AMWUA Notes
A low-water native wildflower that creates iconic spring color; best broadcast among companion plants it can lightly parasitize.
Care Guide
Rely mainly on winter rains, supplementing every 2-3 weeks in dry spells; it needs consistent cool-season moisture to establish and bloom.
None; this tiny annual simply flowers and sets seed, then dries — leave it in place to reseed before clearing.
None needed; it thrives in poor native soil.
Trouble-free.
A cool-season desert annual best sown in early fall; it is partially root-parasitic, so it establishes best interplanted among grasses and other wildflowers, and reseeds to return.
Soil, Feeding & Propagation
Lean, sandy or gravelly native soils; best interplanted among grasses and wildflowers it can lightly root-parasitize.
Needs well-drained soil.
None — thrives in lean desert soil without fertilizer.
Seed; sow in early fall (cool-season) broadcast among host grasses and wildflowers, and it reseeds.
0.5 ft
Partially root-parasitic, so it establishes best among companion plants; reseeds to persist, with no invasive roots.
Placement Tips
- •Sow in early fall broadcast among grasses and other wildflowers, which it lightly relies on as hosts.
- •Mass in bold drifts for the classic desert spectacle of rose-purple spikes.
- •Interplant with poppies and lupine for a layered spring wildflower tapestry.
- •Leave plants to dry and drop seed to renew the colony each year.
Features
Best Uses
Ecological Value
Attracts
Companion Plants
Quick Stats
Design Styles
Include in Your Project
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Use this care guide to maintain your Owl's Clover. Questions about your landscape? Reach out anytime.
Data from 2024 AMWUA “Landscape Plants for the Arizona Desert” guide.
Owl's Clover — common questions
Answers for low-desert Phoenix conditions, drawn from this plant’s growing data.
How much water does Owl's Clover need in Phoenix?
Owl's Clover is a moderate-water annual once established. Rely mainly on winter rains, supplementing every 2-3 weeks in dry spells; it needs consistent cool-season moisture to establish and bloom. A low-water native wildflower that creates iconic spring color; best broadcast among companion plants it can lightly parasitize.
How big does Owl's Clover get?
Expect roughly 0.5 ft tall and 0.5 ft wide at maturity, with a moderate growth rate. Allow about 0.5 ft of spacing when planting. Partially root-parasitic, so it establishes best among companion plants; reseeds to persist, with no invasive roots.
Can you plant Owl's Clover near a pool?
Yes. Owl's Clover is considered pool-friendly, meaning it stays clean enough around water features and hardscape. Litter is rated low.
Can Owl's Clover handle Arizona heat and winter frost?
Owl's Clover is hardy in USDA 9-11 and wants full sun. A cool-season annual in USDA zones 9-11; early-fall-sown for spring bloom in the low desert, it finishes before summer heat and depends on reseeding to persist. A cool-season desert annual best sown in early fall; it is partially root-parasitic, so it establishes best interplanted among grasses and other wildflowers, and reseeds to return.
Does Owl's Clover have thorns?
No. Owl's Clover is thornless, so it is safe alongside walkways, patios and play areas.
Is Owl's Clover safe around pets?
Owl's Clover is listed as pet-friendly in this guide. If your dog is a determined chewer, check any new plant with your vet before planting.
When does Owl's Clover bloom in Arizona?
Owl's Clover blooms in early-late spring, with rose-pink to purple flowers. The bloom draws bees, butterflies.
How much maintenance does Owl's Clover need?
Owl's Clover is low-maintenance. Leaf, flower and pod litter is rated low. None; this tiny annual simply flowers and sets seed, then dries — leave it in place to reseed before clearing.
What kind of soil does Owl's Clover need?
Lean, sandy or gravelly native soils; best interplanted among grasses and wildflowers it can lightly root-parasitize. It needs no supplemental feeding. None needed; it thrives in poor native soil.
Is Owl's Clover native to Arizona?
Yes. Owl's Clover is native to Arizona and to the Southwestern US, so it is adapted to local rainfall, soil and heat.