Rex Begonia Guide: How to Grow & Care for “Begonia rex-cultorum”

Read our guide to Rex Begonia plants for everything you will ever need to know! Tips for planting & caring for “Begonia rex-cultorum”
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The begonia rex is a beautiful plant that will add depth and color to any room in your home. As beautiful as it may be, it is not an easy plant to cultivate. It requires very specific care in order to grow and thrive. It is easy to propagate, so if your first plant fails, replacing it is easier than you can imagine.

Rex Begonia plants are prized by homeowners and home gardeners for their colorful foliage. The textured leaves grow in an array of rich colors that tend to be very dramatic when properly cultivated.

The Rex Begonia often will produce small flowers that are perched above tall stems. They are not essential and can actually result in smaller, less vibrant leaves. To encourage a more dramatic look to your plant, pinch off these flowers as soon as you see them.

Grow these plants in a shallow pot because the roots also thrive when in shallow soil. Being that the plant is rhizomatous, it is important to pay close attention to the soil and root care to ensure the plant has the best chance of proper development.

About the Rex Begonia

  • The botanical name of the Rex Begonia is Begonia rex hybrids.
  • Begonia rex hybrids leaves are a vibrant red color with an interesting texture.
  • The begonia rex needs a very high level of humidity to grow.
  • Rex Begonia’s are also called looking glass plants.
  • This plant is susceptible to fungal infections, mainly bacterial leaf spot.
  • Rex begonia plants have calcium oxalate, which is toxic to dogs and cats.
  • The rex begonia is a native of Southeast Asia.

Rex Begonia Features: An Overview

  • Rex Begonia leaves also grow in purple, cream, pink, and silver.
  • A common name for Rex Begonia is the fireworks plant.
  • Pinching the leaves off of these plants encourages better leaf growth.
  • The Rex begonia plant is rhizomatous.
  • The rex begonia is prone to attacks from fungus gnats and aphids.
  • This plant originated in India and can be found in many places in Southeast Asia.
  • Most rex begonia plants will reach a height of 1 foot at maturity.
  • The begonia rex tends to drop its leave in the winter.
  • Avoid placing these plants in direct sunlight, it will dry out.
Rex Begonia Leaves
Rex Begonia Leaves

Growing The Rex Begonia

Growing the fireworks plant can be a challenge. It is a rhizomatous plant which means that the main part of the plant erupts from the fleshy rhizome that grows under the top layer of soil. Shallow pots are ideal because the roots of thick rhizomes also tend to be shallow.

The plant also needs a high level of humidity in order to survive. If your Rex Begonia leaves are crispy or brittle, chances are the air in your home is too dry for this type of plant. Consider housing your Rex Begonia inside of a glass cloche or a Wardian case to maintain high levels of humidity.

In the winter many begonia rex plants will go dormant. During this phase, they will shed leaves and stop growing. When this happens, all you need to do is stop watering it, remove the wilted leaves, and cover the plant in a plastic bag.

Maintain a steady temperature of around 60 degrees for at least six weeks. This will cause new leaves to spawn after which you can care for the plant as usual. New leaf growth can take anywhere from six to ten weeks depending on the variety of begonia rex you have chosen.

If you notice spots on the leaves, chances are they are a type of fungus. Tan spots are caused by the botrytis fungus which often plagues cool temperature plants in humid climates. If those spots happen to have yellow halos around them, they are certainly bacterial leaf spot.

The best way to treat fungus attacks on begonias is to remove the leaves that have been infected and make sure there is ample circulation around the plant. Make sure your begonia is in sunlight, just not direct. The sun will prevent the fungus from developing on the leaves or over the roots of the plant.

Begonia Rex Plants, From Amazon

Watering The Rex Begonia

Watering the begonia rex requires close attention to detail and careful soil monitoring. This beautiful plant loves humidity, but it does not tolerate overwatering well. Too much water will lead to root rot or a limp plant. If your begonia rex has yellow leaves, chances are you have given it too much water.

Make sure that you use a well-draining potting mix in addition to a pot that has drainage holes. Small pots placed over a draining tray work best. The tray must be drained each time you water to prevent root rot. If emptying the tray is too much of a chore, you can also position the plant over pebbles to prevent the drained water from touching the roots.

The soil should always be moist, but make sure not to get any water on the leaves. Wet leaves can encourage the growth of fungus on the leaves or bacterial leaf spot. They also need a high concentration of humidity, anything between 50% and 70% is ideal. Avoid misting the plant at all costs, but you can place it on a pebble tray or house it in an encasement to maintain proper humidity levels.

The best temperature for the rex begonia is anywhere between 65 degrees and 75 degrees which should be maintained all year long.

Begonia rex-cultorum
Begonia rex-cultorum

Propagating The Rex Begonia

Propagation of the rex begonia is much easier than actually caring for the plant as a whole. You can take a cutting from any healthy leaf in the spring or summer season. Make sure the stem is at least an inch or two long.

Place the cutting at a 45-degree angle in a fresh pot of peat moss and perlite. Cover the whole cutting and pot with a plastic bag to help maintain the proper moisture levels needed for a begonia.

Place this in a warm area of your home, but out of the path of direct sunlight. It takes about a month for the cutting to form roots and another four weeks for the plantlet to emerge. Once a plantlet has sprouted at least three leaves, cut away the parent leaf and pot in a regular pot.

Rex begonias are attractive plants to look at, and also present a great meal for certain pests. Aphids are attracted to new leaves on begonias due to their softness. Fungus gnats also tend to gravitate towards the rex begonia mainly due to the peaty, moist potting mix that allows the begonia to thrive.

It is important to treat these infestations as soon as possible to prevent the spread of these bugs to other plants in your home. Just make sure not to use an insecticide spray on the begonia directly.

The begonia rex loves humidity and plenty of indirect sunlight. Too much water, however, can cause the leaves to turn yellow, so take care to ensure they have moist but not soggy soil.

In Conclusion

Begonia rex comes in over a hundred different hybrid varieties. The majority of these plants are low-growing, however, there are some that are upright. Every option is spectacular, so choose a plant that will fit your personal aesthetics.

The names of the varieties often lend a big clue as to which color leaves the plant will have. For example, the Fireworks variety has silvery green leaves with contrasting purple and black markings. The Merry Christmas variety is a stunning mix of red and green. If you want a truly unique begonia, pick the Escargot variety which has spiral leaves that curl like a snail.

If you have cats or dogs, the rex begonia is not the best choice for your home. The leaves contain a chemical, specifically calcium oxalate that is harmful to both cats and dogs. When choosing a placement for your plant, make sure you put it in a room that has plenty of light, but no direct sunlight. Unlike some house plants, the rex begonia loves fluorescent light. Not only will it grow well, but it will also produce vivid colors and variegation.

Plant your rex begonias in a potting mix based in peat moss. You can also add in vermiculite or perlite to support fast draining. The plant should be fertilized every two weeks during the growing season, but not fed at all during the winter. The fertilizer should be properly balanced and water-soluble.

Overall, this is a beautiful and perfect plant for lovers of all things botanical and unique. The obliquely ovate leaves and vivid colors will make them an attractive addition to any home.


Hollie is a life-long gardener, having started helping her Dad work on their yard when she was just 5. Since then she has gone on to develop a passion for growing vegetables & fruit in her garden. She has an affinity with nature and loves to share her knowledge gained over a lifetime with readers online. Hollie has written for a number of publications and is now the resident garden blogger here at GardenBeast. Contact her at or follow on twitter

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