Boswellia Care Guide | The Charm of the Frankincense Tree and Cultivation Tips

Boswellia is a tree of the Burseraceae family that has been prized since ancient times as the source of frankincense. In recent years, it has surged in popularity as a caudex plant in horticulture. The appeal lies in the beautiful balance of its swollen trunk, distinctive bark, and small leaves, and the way it can be enjoyed in a bonsai-like manner. Here we explain the basics of growing Boswellia.

Boswellia Varieties and Characteristics

About 30 species of Boswellia are known, but only a limited number are available in horticulture. Here we introduce the representative varieties.

Boswellia neglecta is the most widely available beginner-friendly species. Native to East Africa, it features smooth bark ranging from white to gray. It grows relatively quickly, with thickening of the trunk beginning within a few years from seed. Being hardy and easy to manage, it is ideal for those attempting Boswellia for the first time.

Boswellia sacra is the most famous species as the source of frankincense. Native to southern Arabia and Somaliland, it possesses beautiful silvery-gray bark. While growth is somewhat slower than B. neglecta, its trunk thickens with distinctive character, making it popular among collectors.

Boswellia rivae is native to Ethiopia and features distinctive reddish-tinged bark. The trunk thickens readily, and its form is beautiful as a caudex plant. While somewhat difficult to obtain, its cultivation difficulty is roughly equivalent to B. neglecta.

Boswellia pirottae is endemic to Ethiopia and features greenish bark and small leaves that create a delicate impression. Though rarely available in commerce, it has a devoted following among enthusiasts due to its distinctive character.

All these varieties naturally grow in dry rocky areas and cliffs, making them strong in dry conditions and high temperatures, but weak in excessive moisture and low temperatures.

Light and Temperature Management

Boswellia is a light-loving plant, and ensuring maximum light throughout the year is essential for healthy growth.

During the growing season (May to October), outdoor direct sunlight is ideal. Shading is basically unnecessary, as the plant tolerates even intense Japanese summer sun. However, during the rainy season, protect it from prolonged rain by placing it under a rain cover.

For indoor cultivation, place it on a south-facing windowsill or provide 12+ hours of grow light with a plant LED. Insufficient light causes etiolation and excessively spaced leaves, resulting in an ungainly appearance.

While very tolerant of high temperatures, it is sensitive to cold. Most Boswellia species shed their leaves below 10°C (50°F) and risk death below 5°C (41°F). In winter, move indoors and maintain temperatures above 10°C (50°F).

Overwintering is easy in a heated room, but watch for temperature drops at night when heating is off. Windowsills can fall below 5°C (41°F) due to radiative cooling; move plants away from windows at night or insulate with styrofoam boxes.

When moving outdoors in spring, sudden exposure to direct sun can cause leaf scorch. Acclimate gradually over 1–2 weeks by gradually increasing light exposure.

Watering and Soil Management

Watering Boswellia requires careful management that responds to its growth cycle.

During the growing season (May to October when new growth appears), water thoroughly when the soil surface dries. This typically means watering once or twice weekly, but adjust based on temperature, pot size, and soil composition. Boswellia unexpectedly enjoys water during growth; excessive drought halts new growth.

During dormancy (November to April), significantly reduce watering. While some growers completely withhold water, it is safer to water once monthly, just lightly moistening the soil. If the trunk becomes excessively wrinkled, give a small amount of water.

Use well-draining, inorganic-based soil. A basic mix is pumice 3 : hard akadama 3 : volcanic ash 2 : charcoal 1 : vermiculite 1. Boswellia has finer roots than Pachypodium, so small to medium grain sizes work best.

Shallow, wide pots are best for bonsai-style cultivation. Deep pots tend to retain moisture at the bottom, increasing root rot risk. Slitted or unglazed clay pots offer superior drainage and are recommended.

Tree Form and Pruning

One of the great appeals of Boswellia is that its form can be shaped like a bonsai.

Prune during the growing season. Cutting back overgrown branches promotes branching and creates a balanced canopy. A milky-white resin (the source of frankincense) may seep from cuts. This is what makes Boswellia special.

Wiring is possible but not as aggressively as with bonsai. Boswellia branches are somewhat brittle, so wiring thick branches risks breakage. It's safer to wire young, flexible branches or use guide wires to direct growth.

To thicken the trunk, provide ample water and light during the growing season and encourage vigorous branching. Excessive pruning reduces photosynthesis and slows trunk thickening. The basic strategy is to thicken the trunk first, then prune toward the desired form.

Seedling-grown specimens develop particularly beautiful trunk thickening and form rugged, natural caudices. Grafted or propagated specimens rarely achieve the same form, making seedling-grown plants highly valued.

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Frequently Asked Questions and Practical Advice

Here we compile frequently asked questions from beginners and practical advice for each.

Q. What should I start with if growing Boswellia for the first time? A. We recommend starting with hardy, easy-to-care-for established varieties. Widely available varieties have abundant information available, making it easier to find solutions if problems arise. Attempt expensive rare varieties once you have experience.

Q. I don't know when to water. A. When in doubt, don't water. Most plant problems result from overwatering. Lift the pot—if it feels light, it needs water; if still heavy, no watering yet. Insert a bamboo stick into the soil; if it comes out dry, it's time to water.

Q. Is it better to grow Boswellia indoors or outdoors? A. It depends on the variety and your environment. If you have adequate outdoor sunlight, most varieties grow healthier outdoors. For indoor cultivation, consider installing grow lights. In either case, ensuring good air circulation is important.

Q. My plant died, but I don't know why. A. The most common cause is root rot from overwatering. Next is decline from insufficient light, followed by cold damage in winter. Next time, use well-draining soil and extend watering intervals.

Enjoying Frankincense (Resin)

One of the joys of growing Boswellia is being able to harvest frankincense from your own plant.

Resin naturally seeps from well-established plants (with trunk diameter of 3cm or more as a guide). Small wounds promote resin secretion, but minimize damage to the plant by keeping cuts minimal.

Harvested resin hardens when dried and can be burned as incense. Warming it over charcoal or in an incense burner releases a distinctive sweet, refreshing aroma. Enjoying the fragrance revered in ancient Egypt and Mesopotamia at home is a special experience.

However, harvesting large quantities of resin from a horticultural seedling is stressful to the plant, so limit harvesting to small amounts. Prioritize cultivating a healthy specimen over harvesting resin.

Because Boswellia is limited in availability, Botachoku is convenient for sourcing specimens with confirmed varieties. You can purchase seedling-raised plants directly from growers and receive variety verification and cultivation advice.