Rex Begonia Care – The Showiest Foliage Plants

colorful potted Rex begonia

The Rex begonia, care is easy if warm, humid conditions in filtered sunlight can be provided.

Lovers of the Rex consider them the most, brilliant and regal of all foliage plants, and it is fitting they’ve been called “King of the Begonias.”

The conditions under which the Rex begonia is found growing in its native climate are indicative of the requirements that must be substituted when the plant is grown in the greenhouse, sunroom, enclosed porch or indoors.

The Rex Discovery

The first Rex begonia was found in Assam, India, in 1858.

There they were growing to perfection in a tropical region of dense forest. Heat and heavy rains made the air foggy with moisture.

These facts tell us that in our homes they must be kept moist, in a fibrous rich soil, fast draining with the use of clean, sharp sand. They grow best in diffused light in a window garden.

They thrive under fluorescent indoor plant grow lights with perhaps slightly less light than African violets require.

Grown From Rhizomes

Rex begonias grow from a fleshy root-like tuber called a “rhizome.”

This rhizome usually lies on the ground, and masses of small fibrous roots grow from it.

Some varieties are upright growers and the rhizome grows into a vertical position, making a plant that may be two to three feet tall. The commonly-grown varieties of Rex, however, seldom become more than 18 inches tall.

Showy Foliage and Yes… Flowers

The leaf stems are long, erect, very fleshy and hairy. The foliage colors and variations are in countless different combinations, and although rex begonias are known for this colorful “plumage,” they also produce flowers.

Sometimes the flowers are unshowy, and they may be borne beneath the foliage. Other varieties produce flowers above the leaves that are very attractive, and occasionally fragrant.

As an example, the variety ‘Curly Fireflush’ has dark green leaves, edged in black, and the entire leaf is covered with red hairs. Its new leaves resemble red velvet, and the beautiful white flowers are very fragrant.

Humusy Soil

Rexes should have a soil mixture firm enough to hold large plants, yet porous enough for good drainage. A medium of peat moss, and one-third perlite with a few wood ashes and crushed charcoal makes a suitable mixture. Generally a soil that grows quality African violets should be satisfactory for rex begonias.

Drainage Important and Feeding Too

Good drainage is important. Place at least one inch of broken crockery in the bottom of the pot before filling the pot with the soil mixture. Keep moist but not drippy wet.

Use a well balanced fertilizer like Miracle Gro plant food every two weeks, and be sure to follow the instructions given for house plants. Feeding frequently but lightly is much better than an overdose.

I have found that 1/4 teaspoon of nitrate of potash to a six-inch pot will produce strong leaves and beautiful blossoms.

Rex Winters

Few Rexes go dormant in the winter if proper care is given, but if one should drop its leaves, do not throw the plant away.

Set the plant aside and water just enough to keep the stem firm – once a week or every ten days. When new growth starts, prune, keep the soil moist and feed every two weeks with a liquid feed.

Most Rex varieties bloom in the fall or early winter. The use of nitrate of potash through the winter will keep the leaves firm and prevent dropping.

Rex Pest and Disease

Rexes are relatively free of disease and few pests attack them. This is because “bugs” do not like the high humidity and daily spraying that rexes require.


Should mealybugs, red spider, thrip or aphids attack plants, they can be dealt with by spraying with Malathion or Neem.

If the plants are put outdoors in the summer, they must be in a very protected place that is cool and damp.

Such a place will harbor leaf-eating, slimy slugs. Poisons made specifically for these pests can be used to control them. Cabbage or lettuce leaves scattered about in the evening will help. The slugs gather on the leaves and these can be destroyed in the morning.

Rex Begonias are truly showy foliage plants and worth the effort to grow.

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