St. Thomas Bean: A Dramatic Tropical Climber Worth Considering
If you’re looking for a vine that makes a serious statement in your tropical garden, the St. Thomas bean (Entada phaseoloides) might just be your plant. This vigorous perennial climber is known for producing some of the most impressive seed pods you’ll ever see – we’re talking pods that can stretch up to two feet long! But before you get too excited, let’s dive into what makes this plant tick and whether it’s right for your garden.
What Exactly Is St. Thomas Bean?
St. Thomas bean is a twining, climbing plant that can develop woody or herbaceous stems depending on its age and growing conditions. As a perennial, it’s in it for the long haul, which means you’ll want to think carefully about placement since this isn’t a plant you’ll be moving around easily once established.
Where Does It Come From?
Originally native to the Pacific Basin (though not Hawaii), St. Thomas bean has made itself at home in several tropical locations. You’ll find it growing in Hawaii, Guam, and Palau, where it’s considered a non-native species that reproduces on its own and tends to stick around. In Hawaii, it’s actually naturalized, meaning it grows wild without any human help.
The Good, The Bad, and The Climbing
Here’s where things get interesting. St. Thomas bean isn’t classified as invasive or noxious, but it’s definitely a vigorous grower that likes to make its presence known. This makes it a bit of a double-edged sword for gardeners.
The appeal: Those massive, flat seed pods are absolutely stunning and make fantastic conversation pieces. The compound leaves create nice screening, and the small white to cream-colored flowers attract pollinators like bees. If you need to cover a large structure quickly or create privacy screening, this plant delivers.
The considerations: This vine means business when it comes to climbing and spreading. You’ll need a seriously strong support structure – we’re talking sturdy pergolas, large trees, or substantial fencing. It’s not the kind of plant for a small trellis by your front door.
Growing Conditions and Care
St. Thomas bean is only happy in USDA hardiness zones 10-12, so this is strictly a tropical and subtropical plant. If you’re in the right climate zone, here’s what it needs:
- Light: Full sun to partial shade
- Soil: Well-draining soil that doesn’t stay soggy
- Water: Regular watering, especially during dry periods
- Humidity: High humidity levels (it is a tropical plant, after all)
- Support: Very strong, large support structures
Wetland Tolerance
In Hawaii, St. Thomas bean has a Facultative Upland wetland status, which is a fancy way of saying it usually prefers regular garden soil but can handle some wetland conditions if needed. This makes it somewhat flexible in terms of moisture levels.
Planting and Maintenance Tips
If you decide to grow St. Thomas bean, here are some practical tips:
- Start with seeds, which is the most common propagation method
- Plant near a very sturdy support structure from the beginning
- Be prepared for regular pruning to keep it in bounds
- Give it plenty of space – this isn’t a plant for small gardens
- Monitor its spread, especially in naturalistic landscapes
Should You Plant It?
St. Thomas bean can be a spectacular addition to the right garden, but it’s not for everyone. It’s perfect if you have a large tropical property, need quick coverage for substantial structures, and don’t mind a plant that has its own agenda when it comes to growth.
However, since it’s non-native and does naturalize, you might want to consider native Hawaiian climbing alternatives that provide similar benefits while supporting local ecosystems. Native plants are typically better adapted to local conditions and provide more benefits to native wildlife.
If you do choose to grow St. Thomas bean, be a responsible gardener: keep it well-maintained, prevent it from escaping into natural areas, and enjoy those amazing seed pods that are sure to be the talk of your neighborhood!
