San Marcos Hibiscus

Name: San Marcos Hibiscus
Brand: Outdoor Dream Builders

Gossypium harknessii

A compact, very drought-tolerant shrub with yellow and red summer blooms that attract bees, birds, and butterflies.

Hardy in USDA zones 9-11 and frost-sensitive; foliage burns below the mid-20s, so plant in warm low-desert spots and avoid cold pockets.

AMWUA Notes

A very-low-water Baja native and relative of wild cotton; compact and heat-loving, it blooms all summer with minimal irrigation.

Care Guide

💧Watering

Very drought tolerant; water every 2 weeks in summer to keep it full and blooming, then reduce sharply in winter when it may drop leaves.

✂️Pruning

Prune to shape and thin in late winter; this large shrub can be limbed up into a small multi-trunk tree and blooms on new growth, so cutting back promotes flowers.

🌱Fertilizing

Little fertilizer needed in desert soil.

🛡️Pests

Watch for whiteflies in heat, a common issue in its cotton family; otherwise low-trouble.

☀️Seasonal Notes

Evergreen in mild winters, dropping leaves in cold; it carries cheery yellow hibiscus-like flowers with red centers from summer into fall on a large frame.

Soil, Feeding & Propagation

🪨Soil

Well-drained rocky or sandy soils; tolerates caliche and alkaline pH 7.5-8.5.

💧Drainage

Needs well-drained soil.

🌱Nutrient Needs

Low feeder.

🌰Propagation

From seed or semi-hardwood cuttings.

📐Spacing

5 ft

🌳Roots & Placement

Non-aggressive roots; safe near hardscape and pools.

Placement Tips

•A compact mounding shrub to about 4 ft tall and 5 ft wide; space 4-5 ft apart in a border or foundation planting.
•Its cheery yellow hibiscus-like flowers with red centers make a bright filler among boulders and larger shrubs.
•Low litter and clean habit make it a good pool- and patio-side choice.
•Plant in full sun; it flowers most heavily with reflected heat.