Ultimate Guide to Rex Begonia Plant Care at Home

How to Grow and Care for Rex Begonia Plants

Rex begonia, or Begonia rex-cultorum, is a cultivar group of the begonia plant species that produces attractive and abundant foliage with the right care. This plant is a rhizomatous perennial with striking leaves that grow in a variety of vivid colors, shapes, and patterns. Keep reading to discover everything you need to know about how to grow and care for your own rex begonia at home. With the proper conditions, the rex begonia will make an excellent addition to your indoor plant collection.

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Fundamentals of Caring for Rex Begonia Plants at Home

The rex begonia plant thrives in humid environments and exposure to bright indirect sunlight. Pot in well-draining soil and feed with a balanced fertilizer in the spring and early summer months. Allow the top layer of soil to become completely dry in between waterings. The plant requires less water during winter, when it often enters a dormant phase.

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About Rex Begonia Plants

Before you bring this herbaceous perennial home, you may want to research the background of the rex begonia cultivar. Here we’ll cover everything from characteristics to symbolism and care guidance. Soon you’ll be armed with information and steps for caring for your new begonia rex-cultorum plant.

Origins, History, and Etymology of the Rex Begonia

The rex begonia, or begonia rex, descends from the B. rex variety native to zones in eastern Asia. Through the years, gardeners have crossed the species with other rhizomatous begonia varieties, contributing to the nearly 2,000 species of begonia that exist today.

Charles Plumier, a French botanist, coined the word begonia. He named the species after Michel Bégon, a French official and avid lover of botany that lived from 1638 to 1710. The word rex has Latin roots stemming from the word regere, and means ‘a king.’ This may be why the rex begonia earned its nickname, king begonia.

Scientific Classification

The so-called king begonia’s scientific name is Begonia rex-cultorum. Its genus is begonia, and it belongs to the plant family Begoniaceae. Due to its beautiful foliage and flowers, this family has grown to comprise hundreds of plant cultivars and groups, each with its own unique characteristics.

Rex Begonia Botanical Characteristics

Unlike other begonia groups, the rex begonia stands out for its foliage rather than its flowers. While its flowers are small and appear in the spring, its leaves are vivid and evergreen. They form with attractive green, silver, and burgundy hues and patterns ranging from impressive swirls to ivy-shaped leaves.

Where Are Rex Begonia Plants Native?

The rex begonia is native to parts of India, China, and Vietnam, particularly in tropical and subtropical climates. It grows naturally in forests and rocky landscapes. Today, many plant lovers grow the rex begonia as a houseplant all over the world.

Common Rex Begonia Varieties to Grow as Houseplants

Its showy leaves make the rex begonia a common houseplant, though its requirements mean it is challenging for some new houseplant owners. The trick is finding a balance for watering the plant, ensuring it isn’t over or under-watered.

With that said, rhizomatous begonias grow better as houseplants than tuberous varieties since these are more particular about light and humidity levels. A few other common begonia varieties to grow as indoor plants include the following:

• Begonia maculata
• Begonia masoniana
• Begonia erythrophylla
• Begonia acetosa
• Begonia bowerae
• Begonia Cleopatra
• Begonia aconitifolia
• Cracklin rosie begonia

Rex Begonia Toxicity and Pet Friendliness

 The American Society for the Prevention of Cruelty to Animals (ASPCA) lists the rex begonia as toxic to cats, dogs, and grazing animals like horses. This is because of the soluble calcium oxalates in this plant, which can cause kidney failure in grazing animals and vomiting or salivation in cats and dogs upon consumption.

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Rex Begonia Plant Meaning and Symbolism

Despite the bold statement of rex begonia’s foliage, the plant doesn’t make many appearances in religion, literature, or culture. However, the cultivar Begonia Kimjongilia has become a floral icon representing North Korea.

Generally, the begonia has come to represent everything from harmony to gratitude. In the Victorian language of flowers, or floriography, begonias were a symbol of caution.

Feng Shui Qualities

The rex begonia is not known for its Feng Shui qualities. However, the rules of Feng Shui say that a range of thriving houseplants placed intentionally throughout the home can bring good energy. For those interested, it is worth researching the specific areas like career, wealth, and family that Feng Shui can support and how your rex begonia can help.

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How to Grow Rex Begonia Plants at Home (for indoor plants)

There are a few things to keep in mind when growing your rex begonia plant at home. With these tips and considerations on hand, you’ll be prepared to maintain a king begonia as a thriving member of your houseplant collection.

What to Do Before Planting (Key Tips)

Here are a few steps to take before bringing your new rex begonia home.

• Have a wide, shallow potting vessel and saucer ready to repot your new plant.
• Make sure you have the right soil and tools available before repotting your rex begonia. These items are detailed below.
• Find a nice space in your home to place your rex begonia. It will thrive in an area with plenty of indirect sunlight.

Rex Begonia Growth Expectations

Rex begonias typically reach a maximum height of around 1.5 feet. Their shrub-like quality means they will reach a similar maximum spread of around 1.5 feet. Plant growth will accelerate in the warm spring and summer months.

How to Plant a Rex Begonia

The most suitable pots and planters for rex begonias are wide and shallow to make room for their growing rhizomes. Rex begonias prefer a well-draining pot, so clay pots with drainage holes work well. These plants also grow well in a hanging basket.

The ideal pot size for your rex begonia will depend on its current size. Since the rhizomes need room to grow, it is best to ensure the plant has an inch or so of space around the root ball to grow outward. Repotting every year to make extra room for the rhizomes will keep your rex begonia growing happily.

What’s the Best Soil Mix for Rex Begonia Plants?

The best type of soil to use for your rex begonia is a light, balanced potting mix. These plants love well-draining soil that retains some moisture, so adding elements like peat and a layer of stones at the bottom of the container will ensure the plant has everything it needs to thrive. Rex begonias also enjoy loam, sandy, and chalky environments.

Rex Begonia Light Preferences

Your rex begonia will grow best in an area with ample indirect sunlight. You will want to turn the plant regularly to ensure it receives even light across all of its foliage. I’d recommend a quarter turn each week to help your rex begonia maintain even growth.

Temperature and Humidity Preferences

Rex begonias tend to be picky when it comes to temperature and humidity. As begonias are tropical and subtropical plants, they enjoy a mild, moist environment. Their ideal temperature for your rex begonia is between 60 and 70 degrees Fahrenheit.

Despite this plant’s tropical roots, it is important to strike a balance when it comes to moisture. The rex begonia thrives in humidity above 50 percent, but it is sensitive to overwatering and can develop mildew with excess moisture. 

Bathrooms and kitchens are often good locations in the home if you’re growing indoors though a warm spot near a south or east facing window are also excellent options. 

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How to Care for Rex Begonia Plants

How to Water a Rex Begonia Plant:

As a general rule, allow your rex begonia’s soil to drain and dry to between 50 – 75% in between waterings to avoid excess moisture. A soil probe or moisture meter can help to ascertain the precise moisture level though is not essential (simple touch of the soil with your fingers will also give you a good reading). 

The plant may also wilt slightly, which is a good indicator that it is time to water it again. This should occur approximately every 7 to 10 days in spring and summer and around 14 to 21 days during the late fall and winter months.

Water your rex begonia at the base to avoid wet leaves, and avoid overwatering. 

Feeding and Fertilizing Rex Begonia Plants

Your rex begonia will enjoy a balanced fertilizer (meaning an even amount of nitrogen, phosphorus, and potassium – usually referred to as the “NPK” ratio) during its growth period in the warmer months. You can feed it with a complete formula at a quarter strength every 3 to 4 weeks during the summer. Minimize your fertilization schedule as fall approaches, and stop fertilizing the plant during its dormant winter months.

How to Prune a Rex Begonia Plant:

Usually, the king begonia does not require any pruning. If you find that the plant’s rhizomes outgrow the container without producing more foliage, you can trim them back. You can also use these cuttings you take from the rhizome to grow new rex begonia plants.

How to Propagate a Rex Begonia Plant:

Since the rex begonia only lives a few years, a great way to get more longevity from the plant is to propagate it. Follow these steps to propagate new rex begonias from your original plant.

• Gather the supplies you need to propagate your plant: water, scissors, shears, small pots for cuttings and new plants, soil, plastic film, and small stones.
• Take cuttings from a healthy leaf or overgrown rhizome on your plant. You can use a full, healthy leaf by cutting away the stem and making half-inch cuts across the biggest veins in the leaf.
• Place the leaf underside down in the soil using pins, but avoid piercing the veins. The cuts you made are where new plants will grow, so it is essential that these areas touch the soil. You can use stones to keep the leaf flat against the soil.
• Cover the pot with plastic film to maximize the humidity and light it receives. Keep soil moist while your new plants take root.
• Wait up to six weeks for the new plants to grow. Once they are around three inches in height, you can place them into their new pots.

When and How to Repot a Rex Begonia Plant

Typically you’ll want to reconsider repotting your rex begonia every 12 to 18 months to make room for its rhizomes. They spread outward, so focus on increasing the width of the plant’s pot so that it has enough soil to spread and grow.

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Common Rex Begonia Problems and How to Treat them

A lot of common issues that crop up with Rex Begonia plants are related to water and moisture. It is important to find the right balance, not only to help the plant thrive, but to avoid frustrating issues like those mentioned below.

Common Pests and Diseases

Here are a few of the common pests and diseases to know about when it comes to caring for your king begonia plant.

• Powdery mildew
• Bacterial leaf spot
• Botrytis fungal infection
• Mealybugs

Powdery mildew is an especially pesky problem with these plants which can travel to affect other plants in your home. Ensure the affected plant is isolated from other begonias, preferably in an area with good air circulation. Treat the mildew with a fungicide or homemade spray, using a mixture of water, dish soap, and baking soda, until it subsides.

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Essential Tools to Have Around

Now, it’s also great to keep the right tools available for optimal care of your rex begonia. Here’s a list of the tools and materials we’ve mentioned for optimal begonia rex plant care.

• A wide, shallow, well-draining container and saucer, or hanging basket
• Water
• Scissors
• Shears
• Well-draining soil
• A balanced fertilizer
• Plastic film for propagation
• Small pots for cuttings and new plants
• Small stones for propagation or added drainage in the plant’s container

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Wrap Up

The rex begonia cultivar is a dramatic and vibrant plant to incorporate into your houseplant collection. It is a beautiful rhizomatous variety, well worth the effort it takes to care for and grow. With the right attention and maintenance, this regal king begonia will thrive in any space, showing off its deep burgundy, silver, and green foliage for years to come.

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Rex Begonia Plant FAQs:

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