Houseplant collectors everywhere have at least one large leafed tropical tucked in a corner of their home. However, another slightly more subtle group of tropical plants have made their way into our hearts: tropical bulbs!
With their vast array of growth habits, foliage and flowers, we wanted to share some insight into these botanical wonders in a quick guide for growing and caring for tropical bulbs. That way, the next time you have company you can explain that, no, that new plant on the windowsill is not in fact a potato, it's a caudiciform!
Caring for Tropical Bulbs
Let's Talk Taxonomy and Life Cycle
When growing and caring for tropical bulbs, it's important to realize that "bulb" is both a specific botanical term, and also used more generally to refer to a group of plants that have a similar growth cycle.
So before we dive into our favorite species and tropical bulb care instructions, there are a few botanical terms to refer back to.
Bulb: A bulb is actually modified stem consisting of large, globe-shaped, underground bud with membranous or fleshy overlapping leaves arising from a short stem. Many of our favorite springtime flowers, such as Tulips, grow from bulbs.
Tuber: A tuber is a specialized storage stem that is short and thickened, and grows below the soil. Tubers are composed of starch-storing tissue. Caladiums are deciduous aroids that grow from tubers.
A dormant Caladium tuber
Caudex: A caudex is a thickened, usually-underground base of the stem of many perennial herbaceous plants, from which new leaves and flowering stems arise. While these plants may not have anything in common genetically, plants that grow from caudices are called caudiciforms, and an example that we absolutely adore is Stephania erecta.
Corm: A corm is a rounded, thick, underground stem-base bearing membranous or scaly leaves. These act as a vegetative reproductive structure. One tropical example that grows from a corm are members of another aroid genus, Amorphophallus.
Don't fret if you are still scratching your head to try and distinguish these terms! Regardless of their technical taxonomy, “bulb” is the common terminology for plants with a seasonal adaptability and dormancy period in their life cycle. This is just a fancy way of saying that these plants typically die back for part of the year and store energy during their dormant season.
For some of these plants, the period of dormancy might coincide with a dry season. For others (think Tulips), it may coincide with cold weather. In our homes, we mimic these seasonal shifts and trigger dormancy in our tropical bulbs by withholding water in the late fall and winter.
Our Favorite Tropical Bulbs to Grow as Houseplants
Amorphophallus
Curiosity seekers and oddity collectors delight with this spooky tropical bulb. With common names shrouded in mystery such as ‘Corpse Flower’, ‘Devils Tongue’, and ‘Voodoo Lily’, these deciduous aroids grow to look like small trees with foliage that emerges bright green and darkens as it hardens off. Numerous species are available, including one that produces the world's largest flower, Amorphophallus titanum. Another species we adore (that is much more practical to grow in your home!) is Amorphophallus konjac 'Nightstick' -- with a solid, dark-purple petiole, it's simply beautiful.
Amorphophallus operculatus
If growing conditions are just right your Amorphophallus just might flower for you and show you first-hand where it gets its name sake. Though beautiful to behold, the flowers give off the scent of rotted meat to attract fly pollinators native to their natural habitat. While you'll certainly be excited to see the flower emerge, be warned you might want to put a bag over the top to contain the smell!
Amorphallus Care:
- Plant bulb 1-2 inches in fast draining soil amended with perlite, vermiculite, or pumice.
- Give them plenty of bright indirect sunlight.
- Water when new growth emerges from the soil line, allowing the soil to dry to the first few inches in between watering during the growing season.
- In late fall allow foliage to die back and don’t water again until springtime as they need a dry winter rest.
Caladium
Appropriately nicknamed ‘Angel Wings,’ these deciduous aroids look like they were a gift from the heavens with their delicate heart-shaped leaves and stunning colors of pink, red, and green. Caladiums grow in open areas of the forest and on the banks of rivers in their tropical habitats. Native to South America, they thrive during the warm and wet rainy season, and take a rest during the dry season.
Caladium 'Pink Beauty'
A few of our favorite cultivars include Caladium 'Pink Beauty', Caladium 'Cranberry Star', and Caladium 'Gingerland.
Caladium Care:
- Plant bulb smooth side down 1-2 inches below the soil line.
- Water only when actively growing, allowing soil to dry out to the first 1-2 inches.
- Give them bright but indirect sunlight, and a warm environment.
- Stop watering when leaves start to die back in the fall.
- Dig up your bulb and allow to dry out before storing in temperature controlled space for a well-deserved winter rest.
- Plant your bulb in the spring before new growth starts to emerge again.
Stephania erecta
Stephania erecta is a show-stopping statement piece plant that has quickly become one of our favorites to grow. With their potato-like caudex and charismatic round leaves, they are reminiscent of a bonsai. When this bulb comes out of dormancy, it forms vines with green peltate leaves that can be trailing or trained up a trellis.
‘Stephania’ is Greek for ‘crown’, named for the crown-like spiral of leaves arranged at the top of a caudex. They are sure to make you feel like royalty when the first sprout of green pushes its way up and creates adorable round leaves.
Stephania erecta caudex and bulbs
Stephania erecta Care:
- Plant your bulb in well-draining soil mix of 1:1 ratio soil and perlite, leaving the top half of the caudex above the soil line.
- When plant is waking up from dormancy and actively growing water when the soil is dry, making sure they are getting a healthy amount of warmth and humidity.
- Give your bulb bright but indirect light.
- Be cautious with watering as these plants are especially susceptible to rotting; less is more.
As you can see, growing and caring for tropical bulbs opens up a whole new window into the ever-evolving world of houseplants. While we've always enjoyed our irises, tulips, bluebells and alliums outdoors, now you can bring the beauty of seasonal growth into your home with Caladiums and caudices.
What tropical bulbs have you been growing? What have you been searching for?