The genus Boswellia Roxb. ex Colebr. contains the trees that yield frankincense, also called olibanum. This small genus in the Burseraceae family was described in 1807 from Boswellia serrata, and its species grow naturally in the dry regions of tropical Africa, the Arabian Peninsula and India. Collectors prize them for their peeling bark, their swollen, pachycaul habit and their finely divided leaves. They are not easy plants, though: the challenge is to provide the heat, the light and above all the dry winter rest they need in a temperate climate. This article covers container culture, the prospects for planting outdoors, propagation and the main pitfalls.
At a glance
- Climate: dry tropical genus, frost-tender; most cultivated species want a winter minimum of roughly 10 to 15 °C.
- Recommended approach: grow in pots, move outdoors in summer, and bring inside before the first cool nights.
- Substrate: very free-draining and mineral, slightly calcareous for Boswellia sacra.
- Watering: generous in the warm season, almost none during dormancy; winter overwatering is the leading cause of death.
- Propagation: seed has low germination rates; cuttings work but do not develop a swollen trunk.
- In the ground: only in virtually frost-free regions; no reliable documented results found for temperate Europe.
Which species are grown?
Mats Thulin’s 2020 monograph recognises 24 species, ranging from Mali and Burkina Faso to India, with a particular concentration in the Horn of Africa and the Socotra archipelago. A handful turn up regularly in collections:
- Boswellia sacra Flück.: the best-known frankincense tree, native to southern Arabia (Oman, Yemen) and northern Somalia. It is the most widely sold species and one of the slowest.
- Boswellia elongata Balf.f.: endemic to Socotra. A sizeable tree in the wild, it stays much smaller under cover, rarely exceeding 2 m. Some growers report that it grows faster than Boswellia sacra.
- Boswellia neglecta S.Moore: from East Africa (Ethiopia, Kenya, Somalia, Tanzania, Uganda), a caudiciform tree often offered at a moderate price.
- Boswellia serrata Roxb.: Indian frankincense. It is described as tolerant of cool conditions (see below) but remains uncommon in collections.
- Boswellia papyrifera (Delile) Hochst.: Ethiopian and Sudanese frankincense, whose seed is offered by a few suppliers.
Names and taxonomy
The name Boswellia carteri Birdw. is still widespread in the trade and on nursery labels. According to Thulin (2020), as cited in CITES background documents, it is an illegitimate name and Boswellia sacra should be used for a single, variable taxon. Plants of the World Online (Kew), the nomenclatural authority on this site, accepts Boswellia sacra. You will therefore still meet plants labelled Boswellia carteri, or Boswellia thurifera (an old synonym of Boswellia serrata); treat these as names to convert when buying.
In the wild: understanding the needs
Boswellia sacra grows on rocky, mostly calcareous slopes in desert and semi-desert zones, up to about 1,200 m. Other species occupy dry deciduous woodland, thorn scrub or cliffs. These trees receive rare, heavy rainfall followed by long dry months, and shed their leaves for part of the year. Good culture means reproducing that rhythm: a hot, bright growing season followed by a dry rest.
Container cultivation
Growing in a container is the safest approach outside the tropics. It lets you move the tree under shelter in winter and control how wet the root zone gets.
Light and temperature
Give the tree as much light as possible. Most sources recommend full sun or bright partial shade, although one Italian nursery advises avoiding direct sun through glass. For Boswellia sacra, a preference for 27 °C or more is cited. A summer spent outdoors in a hot spot is beneficial, provided the tree is acclimatised gradually to avoid leaf scorch.
Substrate and pot
Drainage is the priority. One nursery suggests equal parts soil, gravel and sand. Collectors also use pumice, lava rock or perlite to lighten the mix. Boswellia sacra lives on calcareous ground in the wild, and some plant databases cite an alkaline pH preference, whereas a seed supplier’s sheet for Boswellia serrata gives a pH of 5.5 to 6.5. It is therefore better not to aim for an exact pH: a mineral, neutral to slightly alkaline mix is enough. Use a deep, perforated pot and repot rarely, preferably as dormancy ends.
Watering and winter rest
Water thoroughly, then let the substrate dry out completely before the next watering, as in the rare rains of their habitat. During dormancy (tree leafless or nearly so), cut watering sharply or stop it altogether, as several suppliers recommend. LLIFLE notes that winter overwatering is probably the main cause of death in Boswellia sacra, which is killed more by kindness than by neglect. Avoid wetting the foliage in full sun.
Feeding
Needs are modest. One Italian nursery applies a single dose of diluted fertiliser a year with the irrigation water, while an LLIFLE entry for a Socotran species suggests a monthly liquid feed in spring and summer. A weak, regular dose during active growth, stopped at dormancy, is a reasonable compromise.
Overwintering
Bring the tree in before the first cold nights, to a bright, dry, frost-free place. Sources disagree on the minimum: an Italian nursery says never below 12 °C, while an LLIFLE entry for a Socotran species recommends 12 to 15 °C in winter yet notes that a cooler rest is useful. A grower in British Columbia (UBC Botanical Garden forum, 2015-2016) overwinters plants under grow lights with heat mats and reports losing one plant in a winter. These accounts show that overwintering is the critical period.
Outdoor and in-ground cultivation
Planting in the ground is only realistic in regions with no frost or almost none. For Boswellia sacra, plant databases give USDA zones 9a to 11 depending on the source, which implies very mild winters, and the University of Arizona Arboretum classes the species as tender. Boswellia neglecta is given for zones 10 to 12, with frost to be avoided.
In a hot, dry region, plant in full sun in a stony, mineral, very free-draining soil, ideally on a slope or bank that sheds water. Avoid hollows where water collects. In a Mediterranean-type climate the main risk is not only cold but also winter wetness: a tree adapted to a dry rest that sits in cold, prolonged rain will rot at the collar. This is horticultural reasoning, not a documented result for a particular species.
Hardiness: what the sources say
The data are thin, mostly from nurseries and general fact sheets, and rarely from measurements over several winters. A few benchmarks:
- Boswellia sacra: described as not tolerating frost (World Plants sheet, Canada); frost-sensitive according to LLIFLE.
- Boswellia serrata: called frost-hardy in the Agroforestree database and by FAO (EcoCrop), but the absolute minimum recorded in its Indian range is 1 to 7 °C, which greatly relativises that “hardiness”. A US seed supplier says it tolerates short spells of dry cold down to about −7 °C but advises protecting it from frost in practice.
- Boswellia neglecta: USDA zones 10 to 12, avoid frost (Desert-Tropicals).
In the sources I consulted, I found no documented in-ground results from temperate Europe or North America. If you have field observations, they would be a valuable addition to this section.
Propagation
Seed
Germination is poor. Rates of 4 to 16% have been reported for Boswellia sacra in Israel, and up to 8% in another trial, according to a study of Socotran Boswellia. For Boswellia serrata, publications give 10 to 20%. The same Socotra study notes a high proportion of empty or insect-damaged seeds depending on the year and locality. Sow fresh seed, in quantity, in a mineral mix, barely covered. A US website suggests covering the pot with plastic film on a heat mat, with the substrate above 25 °C and ideally 32 to 35 °C. Never let the seedbed become waterlogged.
Cuttings
Cuttings are possible. One growing guide proposes stem sections of roughly 15 cm cut at an angle and set in pure pumice, or root suckers. One key point comes from Thulin and Warfa (1987), cited in a CITES document: the characteristic swelling of the trunk does not occur in plants raised from cuttings. For a tree with a thickened trunk, seed is therefore preferable.
Pests and diseases
The main problem is root and collar rot caused by excess water, especially in winter. In their habitat, these trees mostly suffer beetle attacks (families such as Cerambycidae are cited for Boswellia sacra), and Boswellia serrata is exposed to termites in Indian plantations. In collections, expect the usual pests of caudiciform plants kept indoors: watch for mealybugs and spider mites, especially during a warm, dry winter. This is general horticultural advice, not an observation specific to the genus.
Conservation, regulation and toxicity
Boswellia sacra is rated Near Threatened by the IUCN, on an old assessment (Thulin, 1998); the threats cited include overgrazing, resin over-harvesting and insects. Boswellia ogadensis Vollesen, endemic to Ethiopia, is rated Critically Endangered. The genus has been discussed at CITES, including at the 20th Conference of the Parties in 2025, regarding a possible Appendix III listing; I have not verified the final outcome. Before importing seed or plants, check the regulations in force, and buy only nursery-propagated plants, never wild-collected ones. The University of Arizona Arboretum classes Boswellia sacra as toxic: do not ingest it.
FAQ
Can a frankincense tree be grown indoors?
Yes, provided it gets very strong light, summer warmth and a dry, bright winter. The sunniest window or a frost-free conservatory suits it better than a dim living room.
My tree is dropping its leaves: is that serious?
Not necessarily: these are deciduous trees that go dormant. If leaf drop occurs during active growth with damp substrate, suspect overwatering instead.
Can you harvest frankincense from a potted tree?
Not in usable quantities. Commercial resin comes from mature trees tapped in their native habitat.
Which species should a beginner choose?
I found no rigorous comparison. From collectors’ reports, Boswellia elongata grows quickly under cover and Boswellia neglecta is easy to find at a moderate price, but these views are anecdotal.
Reference websites
Plants of the World Online (Kew), genus page: reference nomenclature and distribution, reliable. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:5117-1
Frankincense Resource Portal (Royal Botanic Garden Edinburgh): taxonomy, distribution and conservation of all species, based on Thulin (2020). https://padme.rbge.org.uk/boswellia
LLIFLE, Boswellia sacra entry: growing advice and a warning on winter watering; collaborative encyclopedia, to be cross-checked. https://llifle.com/Encyclopedia/TREES/Family/Burseraceae/12199/Boswellia_sacra
Desert-Tropicals, Boswellia neglecta entry: hardiness zone and frost sensitivity. https://desert-tropicals.com/Plants/Burseraceae/Boswellia_neglecta.html
Plant Lust, Boswellia sacra entry: planting zones and light and soil needs, nursery-supplied data. https://plantlust.com/plants/46043/boswellia-sacra/
University of Arizona Arboretum, Boswellia sacra entry: soil, toxicity, container culture. https://apps.cals.arizona.edu/arboretum/taxon.aspx?id=1075
World Agroforestry, Agroforestree Database, Boswellia serrata: ecology and resilience of the species in its range. https://apps.worldagroforestry.org/treedb/AFTPDFS/Boswellia_serrata.pdf
UBC Botanical Garden forum, discussion on frankincense trees (British Columbia, 2015-2016): growers’ overwintering reports under cover; individual accounts. https://forums.botanicalgarden.ubc.ca/threads/boswellia-tree-frankincense.87354/
Giromagi, nursery (Tuscany, Italy): growing advice and minimum temperature; commercial source. https://www.giromagi.com/en/shop/boswellia/all
Environment Society of Oman, frankincense research programme: threats to Boswellia sacra in Dhofar. https://eso.org.om/frankincense/
Bibliography
Thulin, M. (2020). The genus Boswellia (Burseraceae). The Frankincense trees. Symbolae Botanicae Upsalienses 39: 1-149. [Reference monograph: 24 species, identification key, IUCN assessments and taxonomic notes; basis of the POWO treatment.]
Hamdiah, S.A.S., Karas, L., Houšková, K., Van Damme, K.P.S. et al. (2022). Seed viability and potential germination rate of nine endemic Boswellia taxa (Burseraceae) from Socotra Island (Yemen). [Open-access article (PMC9182641): germination trials and share of empty seeds; also cites the low rates of Boswellia sacra.]
Johnson, S., Abdikadir, A., Satyal, P., Poudel, A. & Setzer, W.N. (2022). Conservation assessment and chemistry of Boswellia ogadensis, a critically endangered frankincense tree. Plants 11: 3381. doi:10.3390/plants11233381. [Status and distribution of the species.]
Johnson, S., Bait Said, A., Vahalík, P., Karas, L., Sarrouf Willson, M. & Bongers, F. Rapid conservation assessment of Boswellia sacra in Oman reveals complex threat and population patterns. [Threats to the Dhofar populations; publication year not verified.]
Purohit, S.D., Tak, K. & Kukda, G. (1995). In vitro propagation of Boswellia serrata Roxb. Biologia Plantarum 37(3): 335-340. [Mentions 10 to 20% germination and the difficulty of vegetative propagation.]
Orwa, C., Mutua, A., Kindt, R., Jamnadass, R. & Anthony, S. (2009). Agroforestree Database: a tree reference and selection guide. [Ecology of Boswellia serrata, drought and frost resistance in its range.]
Forrest, A., Rutherford, C., Stott, G., Olander, S. & Neale, S. (2025). Conservation status, trade and threats to the genus Boswellia (frankincense): executive report. Centre for Middle Eastern Plants, Royal Botanic Garden Edinburgh. [Summary for CITES CoP20; confirms Boswellia sacra as the correct name.]
CITES (2019). Conference of the Parties, 18th meeting, document CoP18 Doc. 66 (Boswellia). [Cites Thulin and Warfa (1987) on the absence of trunk swelling in cutting-raised plants.]