Growing Aulu: Hawaii’s Magnificent Native Shade Tree
If you’re lucky enough to garden in Hawaii and have been searching for a spectacular native shade tree, let me introduce you to aulu (Pisonia sandwicensis). This remarkable Hawaiian endemic has been gracing the islands’ dry and mesic forests for centuries, and it just might be the perfect addition to your landscape – if you can find it responsibly sourced.
What Makes Aulu Special
Aulu, known botanically as Pisonia sandwicensis, is a perennial tree that can truly make a statement in your garden. With its large, glossy green leaves and potential to develop an impressive broad crown, this native beauty offers both cultural significance and stunning visual appeal. As it matures, aulu typically grows as a single-trunked tree reaching heights greater than 13-16 feet, though environmental conditions can sometimes encourage a shorter, multi-stemmed growth pattern.
Where You’ll Find Aulu Growing Wild
This incredible tree is found exclusively in Hawaii, where it’s perfectly adapted to the islands’ unique climate and growing conditions. Aulu has made its home in Hawaii’s diverse landscapes for generations, contributing to the rich tapestry of native Hawaiian flora.
Important Conservation Note
Before you start planning where to plant your aulu, there’s something crucial you need to know. This beautiful tree has a Global Conservation Status of S3, meaning it’s considered vulnerable. With only an estimated 21-100 occurrences and between 3,000-10,000 individuals remaining in the wild, aulu is quite rare. If you’re interested in growing this tree, please ensure you source it only from reputable native plant nurseries that propagate their stock responsibly – never collect from wild populations.
Why Choose Aulu for Your Landscape
There are several compelling reasons to consider aulu for your Hawaiian garden:
- Cultural significance as an endemic Hawaiian species
- Impressive shade canopy for large properties
- Attractive glossy foliage that adds tropical elegance
- Supports local ecosystem when part of native plantings
- Relatively low maintenance once established
Perfect Garden Settings for Aulu
Aulu works best in spacious settings where it has room to spread and show off its natural form. Consider it for:
- Large residential properties with ample space
- Botanical or cultural gardens
- Native plant restoration projects
- Heritage or cultural landscape designs
- Properties seeking authentic Hawaiian character
Growing Conditions and Climate Requirements
Aulu is perfectly suited to Hawaii’s tropical and subtropical climate, thriving in USDA hardiness zones 10-12. This means it’s really only suitable for Hawaii, southern Florida, and similar tropical locations – definitely not a tree for temperate climates!
The good news is that aulu is quite adaptable to different moisture conditions. Its wetland status is listed as Facultative Upland, which means it usually prefers non-wetland conditions but can tolerate some moisture. It does best in well-draining soils and can handle both partial shade and full sun exposure.
Planting and Care Tips
Successfully growing aulu requires patience and the right approach:
- Choose a location with well-draining soil and protection from strong winds
- Allow plenty of space – this tree needs room to develop its natural form
- Be patient during establishment – aulu can be slow to get going initially
- Apply mulch around the base to retain moisture and suppress weeds
- Water regularly during the first few years, then reduce as the tree becomes drought-tolerant
- Avoid heavy fertilization – native plants typically prefer lean soils
Wildlife and Pollinator Benefits
While aulu might not be the showiest pollinator magnet, it does produce small clusters of flowers that attract various insects. As part of a native plant community, it contributes to the overall ecosystem health and provides habitat for Hawaiian wildlife.
The Bottom Line
Aulu is a wonderful choice for Hawaiian gardeners who want to grow something truly special and culturally significant. Its impressive size, attractive foliage, and native heritage make it a fantastic addition to the right landscape. Just remember to source it responsibly, give it plenty of space, and be patient as it establishes. With proper care, you’ll be rewarded with a magnificent tree that connects your garden to Hawaii’s natural heritage.
If you can’t find responsibly sourced aulu, consider other native Hawaiian trees like koa or wiliwili that might be more readily available from native plant nurseries.
