Cool Caladiums

When walking any horticultural trade show floor, my eyes are always scanning for cool plants. What’s the next new, or new to me, plant to jump out and capture my fancy?

This summer, when walking the Cultivate ‘21 show floor, I was quickly drawn in by a couple of new caladium varieties that jumped out from the pack. ‘Burning Heart’ and ‘Hot Flash’ both had me feeling a little flushed. The colors were so unusual I had to stop and get a closer look. My first thought was, why aren’t these marketed as houseplants?

If you don’t already know, the cool kids in the world of houseplant parents are fascinated by growing caladiums indoors. One of my previous students from my UCLA Extension Indoor Plants course now runs his own plant truck in California, called The Haus Plant (find them on Instagram as @thehausplant). You wouldn’t believe me if I told you how much he’s charging for individual pots of caladiums.

Now, this isn't to say that caladiums don’t present challenges as indoor plants, especially if one expects them to stay lush and leafy all year round. But we’ll get to that in a minute.

The genus Caladium, its name derived from the Latinized Malay name kaladi, includes seven species native to South America and Central America. However, this plant gets around. Not only has the species naturalized in parts of Africa, India and other tropical areas, but there are also about 1,000 different named cultivars — likely more at this point, as I’ve probably lost count.

You’ll find Caladium spp. growing naturally along riverbanks and in bright, humid forest areas. This is why caladiums make such a wonderful shade and part shade foliage ornamentals for warm climate gardens.

While research has shown that many plants growing in tropical or subtropical rainforest type environments will put on more leafy growth before the dry winter season (thus transpiring more and potentially bringing back the rainy season), caladiums prefer to punch out and let the big trees do the heavy lifting. As day length shortens (night duration increases, which may only be a negligible change close to the equator but with increasing differences as you move away from the equator), temperatures cool slightly (depending on location) and humidity decreases in the fall season, caladium leaves begin to die down and tubers can enter a type of eco-dormancy for the duration of the dry winter season. The dormant state can last a couple of months, or much longer, depending on the conditions. When the rainy season returns, tubers spring to life again and sprout new leaves.

Now, we all know this dormancy response becomes more dramatic once you hit North America, with more significant photoperiod and temperature shifts. You can bet once temperatures get below 60° F, caladiums will want no part of it. Hardy only to USDA Zones 9-10, tubers must be lifted from the garden after foliage dies down for many gardeners across the U.S. The photoperiod changes are also more significant as you move north, and those shortening days tell the tubers the dry season is on its way.

Photo: © john | Adobe Stock

So, how do these environmental sensitivities influence their use as a houseplant? While you can certainly keep plants warm enough indoors, that may not be enough to keep them from wanting to go into at least a short dormancy. Humidity in indoor environments is relatively low, so that can trigger plants to head south for the winter. Couple the low humidity with the shortening autumn photoperiod (yes, even indoors), and you probably won't be able to stop your caladiums from taking a rest. Now, you could extend your photoperiod with grow lights and keep your caladium under glass or in a glass cabinet to keep humidity high (as savvy plant parents now do by rigging up glass Ikea cabinets and the like), but there’s still no guarantee they won’t take a nap anyway.

What I will say is that allowing your potted indoor caladiums to take a winter rest is much easier than dealing with lifting caladium tubers from the garden and storing them. When the leaves begin to show signs of dying down in autumn, simply reduce your watering until the plant goes fully dormant, clip off all the old leaves and set the pot in a cool dry place for a couple of months. That’s it. Come late-winter or very early spring, as daylengths are increasing, pop your plant back into a sunny window and start to administer small amounts of water. Once the first couple leaves begin to emerge, give your potted caladium a light dose of a houseplant fertilizer to help kick it into gear for spring.

This is a fairly straightforward process, and one that is no different from how we instruct our customers to grow and store indoor-forced amaryllis bulbs, which have a summer rest period. Yet, growing caladiums indoors still seems to be a bit of a mystery for industry pros and home enthusiasts alike. At the rate houseplant enthusiasts are gobbling up all sorts of super-challenging aroids and high-humidity Maranta and Calathea spp., I’m sure they’re willing to take on the caladium challenge.

Repurposing common outdoor crops as unusual and desirable houseplants comes down to giving consumers a few simple step-by-step instructions and helping them envision the plant indoors. If you aren’t marketing common tubers such as caladiums as houseplants, along with other bulbs and corms, you might be missing a fantastic opportunity.