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Begonias are mostly grown as houseplants, especially for their beautifully colored foliage and showy flowers. Interestingly, this species is prized for its foliage rather than flowers. This guide will tell you more about Begonia rex.

Care guide highlights: Known as the painted-leaf begonia, Begonia rex performs quite well in standard potting mix with the addition of peat moss or leafmold for increased acidity, in bright to moderate light with good ventilation and high humidity, higher, in fact, than other begonias. Propagate it from the stem, tip, or leaf cuttings, by division or from seed.  Be wary of direct sunlight which can scorch the leaves and overwatering as it can cause rotting.

Here’s what you will learn in my guide:

  1. Introducing Rex begonias
  2. Do Begonias like sun or shade?
  3. Temperature requirements of Begonia Rex
  4. Desired Humidity Level
  5. Ideal Type of Soil
  6. Potting and Repotting Essentials
  7. How often should you water Begonias?
  8. What is the best fertilizer for Begonias?
  9. Propagation instructions
  10. Is Pruning neccessary?
  11. Pests, diseases and insects
  12. Design with color
  13. Frequently asked questions

Continue reading to find what’s so special about Begonia rex and learn how to grow a healthy one!

Introducing Rex begonias

Begonia rex is a flowering plant that belongs to the rex group of Begonia, the fifth-largest genus of flowering plants.

Rex begonias are distinguished from other plant groups because they have the most vibrant, multicolored, and patterned foliage, in many different shades such as green, red, purple, silver, pink, and brown.

Their leaves are mainly ear-shaped, star-shaped, or spiral with a metallic glow. As such, they steal the limelight when compared to flowers.

The Rex-cultorum group is a large and diverse group of hybrids famed for their exquisite foliage and one such variety is Begonia rex.

Rex begonias hybridize easily because of their equal number of chromosomes 2n=22. They can also hybridize with their distant relatives and turn out to differ strikingly in habit, size, coloration, leaf shapes. B. robusta is one such example, famous in the Rex group.

Begonia rex foliage

About Begonia rex

Originally from Assam, northeast India where it was first discovered, this dramatically foliaged plant is one of the most commercially important in the Begonia genus.

It is a creeping rhizomatous plant with rhizomes that are reddish-brown, somewhat hairy, and rooting at nodes. It can grow around 30-60 cm tall and spread 45 to 90 cm.

The leaves are the star of the show and they are rhizomatous with red, hairy stems that bear large, velvety, metallic green, splashed with silvery-white above and burgundy beneath, often hairy on top and underneath.

In addition, the leaves are heart-shaped, around 30 cm in length, decorated with striking patterns in an array of colors, such as wine-red and tints of green, bronze, and silver.

The flowers appear in winter and they are light in color, consisting of four corollas and a yellow center.

Though commercially important, Begonia rex is rare in cultivation because of its demanding requirements.

Before we proceed, meet these lovely Begonias:

Do Begonias Like Sun or Shade?

Because of its natural mountainous and cloudy habitat, Begonia rex requires greater protection from the sun and more humidity than other begonias.

But just as it has an aversion to the sun, the sun is responsible for the leaf coloration we so desperately want, so a bright spot is a must.

Find a place where it will receive bright indirect or filtered light. East-facing or west-facing windows are ideal sources of sunlight for Begonia rex. South works well in winter but can scorch the plant in summer. 

Due to specific light and humidity requirements, this plant is mainly grown in greenhouses, under artificial lights to stimulate growth. In a greenhouse, install wet pads and fans to lower temperatures.

This plant can even be grown in a shady spot on the floor next to a wet pad and that’s because the atmosphere is humid and cool.

Don't expose Begonia rex to direct sunlight

Temperature Requirements

Normal room temperature suits Begonia rex. Keep daytime temperatures at 21-29 degrees C and nighttime temperatures slightly lower.

Warm temperatures stimulate blooming and this one will flower six to eight weeks after being exposed to warm temperatures.

Maintain winter temperatures above 12 degrees C or higher since it does not like chilly conditions.

Keep away from radiators and heaters in winter.

Related: Plant Temperature- Guide for Gardening Beginners

Desired Humidity Level

High humidity is necessary for the good health of Begonia rex, above 50 percent.

To increase it, place the pot on a tray of wet gravel or stones or use a mister. Group plants close together to retain humidity.

Symptoms of insufficient humidity are crispy, brown leaf markings, and a leaf or flower bud drop. In case you are growing Begonia rex in a contained environment such as in a terrarium, if humidity is too high, fungus and bacteria can appear along with leaf rot.

Begonia rex prefers high humidity

Ideal Type of Soil

As regards the potting medium, Begonia rex is not picky. It can thrive in any type of soil, provided that it is well-drained, pH 5.8 to 6.8, light, and aerated. In fact, multipurpose compost designed for houseplants works just fine.

Alternatively, use a light, open mixture of peat-based soil or 2 parts loam, 2 parts peat, and 1 part sand.

Whatever soil you are using, make it rich, humus works well, sphagnum peat, sand, grit, bark, perlite, and compost.  A little slow-release fertilizer is also recommended when planting.

Potting and Repotting Essentials

When you pot or repot your Begonia rex, do not plant it from a small to a very large container. Excessive amount of potting soil around the leaves can retain water and produce weaker growth.

Pot up one size container at a time. Use a fresh mix, add fertilizer, water it and keep it in subdued light for some time before exposing it to more sunlight.

Another reason why you need to choose a shallow pot is that its root system grows horizontally.

Transplant only when your Begonia is root-bound. Spring is the best time.

Repot Begonia rex only when the plant is root-bound

How Often Should You Water Begonias?

Keep the soil mix moist, but not wet or soggy, from spring to fall.  Water twice weekly in summer and every 10 days in winter with soft or distilled water.

Avoid overwatering during the growing season, and let the soil to dry out during colder months. Also, the soil should dry out between two watering sessions.

Frequent watering and sitting in the water will damage the root system and lead to rot.  So, avoid overwatering by all means. If you overwater, the leaves turn yellow and drop off.

When watering, direct your watering can at the soil surface and avoid watering the leaves. What you can do is sit the plant on a tray of damp pebbles, but do not mist the leaves so as not to invite fungus or bacteria.

What Is the Best Fertilizer for Begonias?

For optimum growth, feed the plant with a liquid high-potassium fertilizer every two weeks in early spring, summer to late fall to enhance blooming.

Cut the concentration by half if you are not experienced in fertilizing and follow the manufacturer’s guidelines as regards the application process.

Refrain from fertilizing newly repotted plants for about one month.

Fertilize Begonia rex to promote blooming

Propagation Instructions

To propagate Begonia rex, cut 5-7 cm sections of rhizome, each with a growing point, and plant shallowly. Cover it with a plastic bag to maintain the desired level of humidity.

Alternatively, propagate it via leaf cuttings, and here is how you should do it:

Tools for propagation

  • Sharp, sterile knife
  • Cutting board
  • Plastic pots or small tray
  • Clear bags and rubber bands
  • Small watering can with a rose attachment
  • Small pots
  • Spoon
  • Multipurpose compost + supplements of your choice
Begonia rex propagation

Procedure- step by step

  • Water the plant before taking the cuttings
  • Cut a healthy, large leaf of a mature plant with 3 cm of leafstalk by removing it at the base of the stem
  • Dip it in rooting hormone
  • Place on a clean cutting board
  • Divide the leaf into sections about 2cm long, each with veins running through them
  • Plant the leaf cuttings in a pot or tray of soil at an angle of 45 degrees so that it sticks in new soil like an umbrella
  • The veins should be in contact with the compost
  • Add a handful of perlite and press down gently
  • Then, firm the soil around the base of the stem
  • Water the soil around it using a small can and tap out the excess water
  • Enclose it in a plastic bag secured with a rubber band
  • Leave in a warm area protected from direct sunlight
  • It takes up to two months for little plantlets to appear around the stem
  • When 3 leaves appear, remove each cutting using a spoon, paying attention not to damage the roots
  • Transfer into small pots of multipurpose compost
  • Water well and place in a warm, bright spot

How to take leaf wedges?

  • Cut off a leaf from the petiole
  • Remove its leaf stems
  • Cut the leaf into a wedge shape with the main middle vein intact
  • Dip the pointed tip in rooting hormone
  • Push one-third of the wedge (the point) into the moist rooting medium (soil)
  • Firm the soil around it
  • Water it
  • Enclose it in a plastic bag to increase humidity
  • A new plant will grow in a few weeks

Propagate Begonia rex from stems

  • Cut the stem a few inches from the tip
  • Strip off side leaves to prevent wilting
  • Dip the stem in rooting hormone
  • Firm the stem into soil
  • Water it
  • Enclose it in a plastic bag for a few weeks
Begonia rex- successful propagation via leaf cutting

Is Pruning Neccessary?

Rhizomatous begonias can be rejuvenated by cutting back the old rhizomes and swollen appendages. You can also remove straggly growth.

Pests, diseases, and insects

Begonia rex may have trouble with mealybugs, root-knot, weevils, and powdery mildew.

Mealybugs are pests that produce soft white wax and should be treated by removing affected areas with alcohol. In case the plant is heavily affected, use horticultural oils and insecticidal sprays outside.

Weevils feed on begonias at night and produce a notched pattern on leaf edges. Treat them by pouring insecticides into the soil.

Powdery mildews are fungi that produce white marks on leaves, stems, and buds and like cool temperatures, high humidity and wet leaves, and above all healthy plants. To prevent this, water Begonia rex in the morning so that leaves can dry if you splash them, but avoid doing that.

Red spider mites, whiteflies, and thrips can also visit Begonia rex, so regularly inspect all your plants and act promptly, at the first sign of some undesirable occurrence.

Related: Cleaning Houseplants – Guide for Gardening Beginners

Design with Color

Color is a powerful tool for evoking emotion and creating a particular atmosphere and mood. Marvelous, bold, and eye-catching as it is, Begonia rex should be displayed with careful thought and meticulous attention.

Purple foliage adds another dimension to the otherwise dull green array of houseplants and settles a welcoming mood.

Begonia rex display ideas

Plant it in a cool gray medium size, round, shiny pot if you want to achieve a harmony of color. If you want to add some contrast in terms of color, choose a pot that’s honey, lemon-yellow, or orange to make it a focal point.

Regardless of where you pot it, Begonia rex is bound to attract attention because it is itself an artistic piece of color and design.

Care tips in a nutshell

  • Clean leaves regularly to increase the amount of light that reaches your Begonia rex
  • Turn your plants every few days so that each side receives enough sun and develops that purplish color evenly
  • Use grow lights to imitate the sun’s rays
  • Keep away from draughty areas like hallways and hot, dry areas near radiators, open fires
  • Water every 4 days to keep the compost moist and tip out excess water
  • When buying Begonia rex, choose one with crispy leaves and no markings

Frequently Asked Questions

Conclusion

Begonia rex is a show-stopper flowering species famed for its unique foliage. It pairs well with African violets, bromeliads, ferns, and any low-light plants.

Your visitors are bound to marvel at the beauty of it and will certainly be amazed if you give one to them as a present.

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