What hardiness zones is Agastache rupestris suitable for?

Agastache rupestris is suitable for USDA hardiness zones 5, 6, 7, 8, 9.

What are the sun requirements for Agastache rupestris?

Agastache rupestris requires Full Sun.

How much water does Agastache rupestris need?

Agastache rupestris has Very Low water needs.

Perennials

Agastache rupestris

Sunset Hyssop

Lamiaceae

Southwestern United States (Arizona, New Mexico)

At a Glance

TypePerennial

HabitMounding

FoliageDeciduous

Height18-30 inches (45-75 cm)

Width18-24 inches (45-60 cm)

Maturity2 years

Growing Zones

USDA Hardiness Zones

5 - 9

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Attracts Butterflies

Attracts Hummingbirds

Deer Resistant

Drought Tolerant

Fragrant (moderate)

Container Friendly

Native to North America

Maintenancevery low

Overview

Agastache rupestris is a mounding, semi-woody perennial reaching 18–30 inches (45–75 cm) tall and 18–24 inches (45–60 cm) wide. Stems are square in cross-section, branching freely from a woody base, with narrow, silver-gray to gray-green leaves 0.5–1 inch (1.3–2.5 cm) long. Foliage is strongly aromatic, releasing a licorice-mint scent when brushed. Flower spikes are loose, 4–8 inches (10–20 cm) long, with salmon-orange tubular flowers 0.5–0.75 inch (1.3–2 cm) long emerging from persistent lavender calyces. The two-toned effect of orange petals against lavender calyces persists after petals drop, as the calyces retain their color for several weeks. Bloom occurs July through October, with continuous flower production over 8–10 weeks. Plants self-seed moderately in loose, well-drained soils. Growth rate is rapid; plants reach full size within 1–2 growing seasons. Stems become woody at the base with age. Plants are short-lived (3–5 years) in humid climates with heavy, wet winter soils. Root rot is the primary cause of decline, developing rapidly in waterlogged conditions. Crown hardiness is zone 5 with sharp drainage; plants may not survive zone 5 winters in clay soils.

Native Range

Native to the southwestern United States, found in Arizona and New Mexico. Grows on dry, rocky slopes, cliff faces, and canyon walls at 5,000–8,000 feet (1,500–2,400 m) elevation in well-drained, mineral soils.

Suggested Uses

Commonly planted in rock gardens, xeric borders, gravel gardens, and pollinator plantings at 18–24 inch (45–60 cm) spacing. Tolerates lean, rocky soils and full sun. Not suited to heavy clay, irrigated beds, or humid-winter climates without exceptional drainage.

How to Identify

Distinguished from A. foeniculum and other blue-flowered Agastache species by salmon-orange flowers with persistent lavender calyces, narrow silver-gray leaves, and mounding habit. Leaves 0.5–1 inch (1.3–2.5 cm) long, much smaller and narrower than those of A. foeniculum. Stems become semi-woody at the base. Strong licorice-mint fragrance when foliage is crushed.

Appearance

Size & Dimensions

Height1'6" - 2'6"

Width/Spread1'6" - 2'

Reaches mature size in approximately 2 years

Colors

Flower Colors

orange

pink

purple

Foliage Colors

gray

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~10 weeks

SummerFall

Flowers July through October in zones 5–9. Individual flower spikes bloom continuously, with petals dropping while lavender calyces persist for 2–3 additional weeks. Total bloom period extends 8–10 weeks. In zone 9, bloom may begin in late June. Flowering slows when night temperatures consistently drop below 45°F (7°C).

Detailed Descriptions

Flower Description

Salmon-orange with lavender calyces

Foliage Description

Silver-gray to gray-green, narrow, aromatic

Growing Conditions

Sun Requirements

Full Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 8.0(Neutral)

357912

Soil Types

sandloamrocky

Drainage

well drained

Water & Climate

Water Needs

Very Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Water sparingly once established; overwatering is the primary cause of plant decline. Native to rocky, well-drained slopes, this species is intolerant of clay soils and waterlogged winter conditions. Amend heavy soils with coarse gravel or pumice at planting to improve drainage. Plants require full sun for 6 or more hours daily; stems become lax and flowering decreases in shade. No fertilization is needed; excess nutrients promote soft growth susceptible to winter kill. Spider mites develop in hot, stagnant conditions. Plants are typically short-lived (3–5 years) in the Pacific Northwest and other humid-winter climates.

Pruning

Cut stems back to 4–6 inches (10–15 cm) above ground in early spring (March–April) after the last hard frost but before new growth emerges. Do not prune in fall — dried stems protect the woody crown from winter moisture. Deadheading during the growing season extends bloom. Self-sown seedlings can be transplanted or removed in spring.

Pruning Schedule

early spring

Maintenance Level

very low

Container Growing

✓ Suitable for container growing

Minimum container size: 3 gallons

⚠️ Toxicity Warning

Non-toxic