“Near the sitting area under an ash — 'a pretty rare tree... one I always wanted.' True desert botanical; winter is the question.”
Background
The genus Boswellia (Burseraceae) holds roughly two dozen species of frankincense trees spread across the arid Horn of Africa, the Arabian Peninsula, and parts of India. Frankincense resin has been harvested by scoring bark and collecting the hardened sap for at least 5,000 years. Matt's eight species span the genus: sacra and carteri (Oman/Somalia), papyrifera (Ethiopia/Eritrea/Sudan, the source of most commercial frankincense), serrata (India), neglecta, elongata, asplenifolia, and the Socotra endemics dioscorides and socotrana. Species vary in cold tolerance, so hardiness notes below are genus-level and conservative.
Distinguishing traits
Small deciduous trees or large shrubs with papery, peeling bark, pinnate compound leaves, and small yellow-white flower clusters; some species develop swollen, sculptural trunks. Extremely slow growing; wild specimens reach 20-30 ft over decades. Leaves drop in the dry season and flush with moisture; a leafless tree in winter is dormant, not dying.
Desert care — zone 9b
- Chill hours
- n/a — ornamental
- Cold hardiness
- No real frost tolerance; sustained exposure below about 40°F risks serious damage or death. Outdoor year-round culture is realistic only in zones 10b-12. Queen Creek's brief freezes are the central risk — container culture or serious winter protection is the practical path, exactly as Matt's note flags.
- Heat tolerance
- Exceptional; evolved for scorching dry heat and intense sun. The dry heat of Arizona suits it better than humid climates.
- Water
- Water thoroughly only when soil is fully dry, in pulses like desert rainfall. Dramatically reduce or stop watering in winter dormancy. Overwatering and root rot are the top killers in cultivation.
- Soil
- Fast-draining, mineral-heavy mix (coarse sand, pumice, perlite); tolerates limestone/calcareous soils. Consider inoculating with mycorrhizal fungi, which research shows strongly benefits Boswellia establishment.
- Sun exposure
- Full sun, 6-8+ hours; growth slows and stretches in shade.
Where to buy
- Miniatree Garden (Tempe, AZ)