Gardeners' Dirt: Wrinkled, variegated leaves distinguish rex begonia
By Jean Knowles - Victoria County Master GardenerEdited by Charla Borchers Leon
June 20, 2013 at 1:20 a.m.
Want color, texture and variety that thrives in a shady place? The answer is rex begonia.
The rex begonias of today are all descended from the Indian species B rex that was discovered in the mid-1850s. That B rex was crossed with other types of rhizomatous begonias to produce the many hybrids that are currently in existence.
Wrinkled, colorful variegated leaves
Rex begonias have been developed in a variety of sizes, shapes and colors of leaves that grow on short leaf stalks from underground rhizomes.
The rex begonia has wrinkled, variegated leaves and is different from other fancy-leafed begonias with thick, hairy stems and undersides of the leaves.
The rex begonia does bloom, but the blooms are insignificant compared to the foliage, so it is recommended that the flower and flower stalk be removed so the plant can put all its energy into leaf production.
With names like "Cancun" "Christmas," "Fireworks," "Curly Fireflush" and "Flamingo Soul," you can imagine the color and variety Rex begonias can bring to your garden.
These hybrids are not readily available by name at garden centers or area nurseries. Typically, the tag says "Red Rex Begonia" or "Curly Leaf Rex Begonia" or just "Rex Begonia." But it does not matter if you know the name of the hybrid as you can certainly enjoy its beauty and variety.
Prefer indirect light
Rex begonias prefer bright, indirect light year-round. Because they do not bloom as much as other begonias, they can tolerate less light and can even grow under fluorescent lights or indoors with bright, indirect sunlight. They should never have direct sunlight.
Thrive on humidity, not overwatering
Like all begonias, rex begonias do not like being overwatered. They prefer even watering but like to dry out about an inch down before watering. They thrive on humidity.
It is recommended to put a layer of gravel in the dish under the pot and keep a bit of water in the dish. Lack of humidity causes the leaf edges to become crisp and dry, and the plant just does not flourish.
Need winter protection
Rex begonias are cold tolerant in Zone 10 and 11 so they need to be protected in the Victoria area. Some go into dormancy during winter.
Do best in drained soil
Rex begonias prefer an airy, light, fast-draining soil such as the prepared African violet potting mix. It is recommended a weekly feeding with 14-14-14 until fall and then tapering off until early spring when the plant puts on a growth spurt.
Require air circulation to prevent mildew
Powdery mildew can be a problem. Good air circulation is necessary. When watering avoid spraying water on the leaves as standing water encourages powdery mildew.
If powdery mildew is found on a plant, separate it from the rest immediately and treat with a fungicide. If you buy a new plant keep it separate for a while to insure you are not bringing in a problem.
Rex begonias will only thrive for a few years, but that is not a problem because they are so easy to propagate.
Early spring when the plant is about to begin new growth is the best time to propagate.
Cut the tip of the rhizome or cut off the edge of the rhizome that has grown over the pot. If the rhizome is upright, cut it back partway. This forces new growth along the rhizome and makes the parent plant fuller.
It would probably be the right time to move the parent up to the next size pot with fresh potting soil. Then plant the rhizome in the same light potting mixture. You can use a rooting hormone, and you will have a new plant that is true to the parent.
Two other methods
For the patient gardener, there are two other methods to propagate hybrids. One is to pin down the leaf in a rooting mix and make small incisions in the leaf veins. Keep the mix moist, not wet, and covered and at each incision a new plant will grow. Or a leaf with a petiole can be placed in the rooting mix and a new plant will sprout at the petiole.
Do not let the information in this article scare you away from trying these stunning plants in your home, on your patio or even in the shade garden.
Small plants can be purchased at local garden centers for less than $5 and they will quickly fill a 6-inch pot. Yes, they have specific requirements, but their beauty makes it worth the effort - and you will have great gifts for all your gardening friends.
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column at VictoriaAdvocate.com.