Rex Begonias come in a wide range of cultivated varieties, with vibrant multi-colored leaves in all sizes.
They’re a low light tropical houseplant with underground succulent rhizomes that need to be kept relatively dry. And yet the leaves need moisture – a puzzle indeed. But not too difficult to solve. Follow along.
Soil: They need a fast-draining soil that will dry out fully between waterings. A high quality houseplant mix will work – but be wary of lower quality mixes because they hold too much moisture. An orchid blend is even better. If you use a cactus or succulent blend, we recommend adding coir chips or a little bark mulch to the mix, or even some vermiculite.
Light: For the best vibrant colors, we recommend bright indirect light only. If they’re going to get some direct sun, make sure it’s no more than 1 to 2 hours of morning sun, and not too close to the window or the plant can burn.
Watering: Here’s what we’ve discovered as the key to successful rex begonias in the Bay Area with wet winters and dry summers. It all depends on the temperature in your home through the year.
Below 60° – The plant is going to go semi-dormant, so reduce watering to every 2 weeks and let some of the leaves fall off for winter.
60’s – Water once per week, letting the soil dry out completely, and don’t mist.
70s – Water weekly, and mist the leaves occasionally with a very fine spray.
80s – Water weekly, and mist the leaves 2 to 3 times per week with a very fine spray.
90° and above – Water twice weekly, mist the leaves every other day or place on rocks in a saucer filled with water to increase the ambient humidity. Don’t let the pot sit directly in the water.
Watering Note: Always let the roots dry out between watering and never let the pot sit in water.
Misting Note: When misting rex begonias always use a very fine mist and never let water droplets collect on the leaves.
If you live elsewhere your results will vary, depending on your temperatures and especially your humidity.