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Plant care

Smooth Arizona Cypress (Smooth-barked Arizona Cypress) care

Cupressus arizonica var. glabra

Also called Smooth Arizona Cypress, Smooth-barked Arizona Cypress, Glabra Cypress.

RHS H4USDA 7-9Mildly toxic to petsIndoor 10–20 m tall (33–65 ft)

Watering rhythm

Direct sun (at least 4-6 hours)

Infrequently; highly drought-tolerant once established

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Light

Direct sun (at least 4-6 hours)

Soil

Well-drained rocky, gravelly, or loamy soil

Humidity

Very low to moderate (20–50% RH)

Temp

-18 to 43°C

Pet safety

Mildly toxic to pets

Mature size

10–20 m tall (33–65 ft)

Care at a glance

Light

Smooth Arizona Cypress needs sun on the leaves, not just bright ambient room light. Requires full sun — at least 6 hours per day. In its native habitat it grows on exposed hillsides in full sun. Shade produces etiolated, weakened growth and diminishes the ornamental foliage colour. Site in an open, sunny position away from overhanging trees. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Water smooth arizona cypress infrequently; highly drought-tolerant once established. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. One of the most drought-tolerant conifers. Once established (2–3 years), mature plants require little to no supplemental irrigation in most climates. Water deeply but infrequently during establishment. Avoid overwatering or planting in areas of poor drainage — wet soils are the primary cause of mortality.

Soil and pot

Smooth Arizona Cypress grows best in well-drained rocky, gravelly, or loamy soil. Thrives in poor, rocky, or gravelly soils with excellent drainage and pH 6.0–8.0. Tolerates alkaline, chalky, and sandy soils. Does not tolerate clay or poorly drained soils. Ideal for slopes, berms, and sites where drainage is naturally excellent. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Smooth Arizona Cypress sits happiest at around Very low to moderate (20–50% RH) humidity and -18 to 43°C (0 to 110°F). Adapted to the hot, dry climate of the Arizona chaparral and mountain foothills. Among the best conifers for hot, dry, low-humidity environments. Performs poorly in climates with high summer humidity and waterlogged soils. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed smooth arizona cypress sparingly. Does not require fertilisation in typical garden conditions. In very poor soils, a light application of a balanced slow-release fertiliser in early spring can support establishment. Avoid fertilising mature trees — this species is adapted to nutrient-poor soils and excess feed promotes rank, weak growth. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on smooth arizona cypress in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Seiridium canker — Seiridium unicorne fungal canker causes branch dieback, resin exudation, and orange-brown foliage streaks. It is stress-related, most common in humid climates or over-irrigated sites. Prune out affected branches to clean wood; improve air circulation and avoid overhead irrigation.
  • Root rot in poorly drained soils — Despite its toughness in drought, this species is highly susceptible to Phytophthora and Armillaria root rots in wet or clay soils. Site selection is the only prevention; there is no chemical cure. Plant on slopes or raised beds where drainage is guaranteed.
  • Cypress aphid (Cinara cupressi) — Infestations of large grey-green aphids can cause yellowing, branch dieback, and sooty mould on young trees. Check the inner canopy in early spring. Treat with insecticidal soap or pyrethrin-based sprays; natural predators (ladybirds, lacewings) provide biological control.

Propagation

By seed: sow in spring without pre-treatment, or lightly cold-stratify for 4 weeks. Germinates readily at 18–22°C in well-drained compost. Semi-ripe cuttings in late summer with rooting hormone and bottom heat (20–22°C) root moderately well. Named cultivars (e.g. 'Blue Ice') are propagated by cuttings to maintain foliage colour. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Smooth Arizona Cypress is mildly toxic to pets. Cupressus arizonica is not specifically listed by ASPCA. Cypress species generally have low toxicity profiles; however, the foliage, bark, and resin contain aromatic oils and terpenes that can cause mild gastrointestinal irritation (vomiting, drooling) if ingested by dogs or cats in significant quantities. Not considered severely toxic. Contact a veterinarian if large quantities are consumed. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Smooth Arizona Cypress care — frequently asked questions

What is the common name for Cupressus arizonica var. glabra?

Cupressus arizonica var. glabra is most commonly called Smooth Arizona Cypress, but it is also known as Smooth Arizona Cypress, Smooth-barked Arizona Cypress, Glabra Cypress. The names refer to the same species, so care instructions for Smooth Arizona Cypress apply identically to anything sold as Smooth-barked Arizona Cypress.

How much light does smooth arizona cypress need?

Smooth Arizona Cypress grows best in direct sun (at least 4-6 hours). Requires full sun — at least 6 hours per day. In its native habitat it grows on exposed hillsides in full sun. Shade produces etiolated, weakened growth and diminishes the ornamental foliage colour. Site in an open, sunny position away from overhanging trees.

How often should I water smooth arizona cypress?

Water smooth arizona cypress infrequently; highly drought-tolerant once established. One of the most drought-tolerant conifers. Once established (2–3 years), mature plants require little to no supplemental irrigation in most climates. Water deeply but infrequently during establishment. Avoid overwatering or planting in areas of poor drainage — wet soils are the primary cause of mortality. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is smooth arizona cypress toxic to cats and dogs?

Smooth Arizona Cypress is mildly toxic to pets. Cupressus arizonica is not specifically listed by ASPCA. Cypress species generally have low toxicity profiles; however, the foliage, bark, and resin contain aromatic oils and terpenes that can cause mild gastrointestinal irritation (vomiting, drooling) if ingested by dogs or cats in significant quantities. Not considered severely toxic. Contact a veterinarian if large quantities are consumed.

What USDA hardiness zone does smooth arizona cypress grow in?

Smooth Arizona Cypress is rated for USDA zone 7-9 and RHS hardiness H4. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Smooth Arizona Cypress deep-dive guides

Every aspect of smooth arizona cypress care, each with its own calibrated guide:

Featured in these plant shortlists

Smooth Arizona Cypress qualifies for 5 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Smooth Arizona Cypress is also known as Smooth Arizona Cypress, Smooth-barked Arizona Cypress, and Glabra Cypress.