Shrub
Japanese Boxwood
Buxus microphylla var. japonica · Buxaceae
Also called: Littleleaf Boxwood, Boxwood
Japanese Boxwood (Buxus microphylla var. japonica) is a moderate-water shrub well suited to Tucson and the low desert. It thrives in full sun to partial shade, with a slow growth rate.
Japanese Boxwood at a glance
- Water use
- Moderate (established)
- Sun
- Full sun to partial shade; in Tucson strongly prefers afternoon shade or filtered light. Full afternoon/reflected sun bronzes and scorches the foliage, especially in summer and winter.
- Mature size
- Typically 3-6 ft tall and wide if unpruned; usually kept clipped to 1-3 ft as a low hedge.
- Growth rate
- Slow
- Bloom
- Inconspicuous greenish-yellow (not ornamental), Inconspicuous small greenish-yellow flowers in spring; grown strictly for evergreen foliage, not bloom.
- Cold hardiness
- Cold-hardy well below Tucson lows (to about 5-10°F); evergreen here with possible winter bronzing of leaves. No frost protection needed.
- Soil
- Needs well-drained soil; tolerates alkaline soil but performs better with organic amendment and consistent mulch. Poor drainage causes root rot.
- Native range
- Japan
- Best used as
- Formal clipped hedge, Low border/edging, Topiary, Foundation planting, Knot gardens and formal courtyard designs
- Wildlife
- Of little wildlife or pollinator value; deer-resistant.
- Toxicity
- Toxic. All parts contain alkaloids (buxine) that are toxic to dogs, cats, horses, and humans if ingested, causing vomiting and digestive upset. Keep clippings away from pets and livestock; bitter taste usually deters serious ingestion.
How to grow Japanese Boxwood in Tucson & the low desert
Watering
Water regularly and deeply to keep the shallow root zone evenly moist — roughly every 4-7 days in summer heat and every 2-3 weeks in winter. It has low drought tolerance in the low desert and declines if allowed to dry out. Mulch to keep roots cool and moist.
Fertilizer & nutrients
Apply a balanced or slow-release fertilizer in early spring; boxwoods are prone to iron and nitrogen deficiency (yellow/bronze foliage) in alkaline desert soil — correct with chelated iron and light feeding. Avoid fertilizing in late summer.
Pruning & care
Tolerates frequent shearing; trim to shape spring through early fall for formal hedges, topiary, or low borders. Thin interior occasionally to allow light and air into the plant. Avoid pruning right before a hard freeze.
Notes
More heat- and sun-tolerant than English boxwood, making it the better boxwood choice for the low desert, but it is still a higher-maintenance, water-needing plant best sited in shade. Watch for spider mites in hot, dry conditions and for iron chlorosis in alkaline soil.
Sources: University of Arizona Cooperative Extension / Pima County Master Gardeners; AMWUA Landscape Plants for the Arizona Desert; Reputable Southwest horticulture references