Rex begonia are richly colored house plants that are known for their patterns with vibrant foliage.
There are many types of them available on the market, but the most common one has that signature lime green with pink staining on the large leaves.
They DO require extra care compared to other houseplants, but it’s nothing even a newbie can’t do!
With patience and a dedication to learning about Begonia x rex-cultorum, you can make them thrive indoors.
Guide Contents
Toxicity warning!
Rex begonias are toxic to dogs, cats, and sensitive individuals.
The plant contains insoluble calcium oxalate, which is found all over the plant, but especially in the leaves, stems, rhizomes, and roots.
Contact or ingestion can cause vomiting, salivation, or other adverse effects. Ensure that people and pets can’t come into contact with it.
Wear gloves and proper protective gear when handling.
Always wash your hands thoroughly after contact, or any other object or body part that touches it. It can also cause skin irritation.
Quick care guide: Rex begonia
| Plant type | Perennial |
| Origin | Northeastern India, southern China, and Vietnam. |
| Scientific name | Begonia rex |
| Other names | Fancy-leaf, painted-leaf or king begonias |
| Soil type | Organic, peat-based, loose, rich, loose, well draining |
| Soil pH | 5.7-6.4 (acidic) |
| Sunlight requirement | Partial, shaded, dappled sunlight |
| Bloom season | Summer |
| Colors | Orange, red, lime, pink, yellow, rose, lavender, maroon, green, purple, silver, pink, hybrids |
| Max height | 2 feet |
| Max width | 2 feet |
| Low temperature tolerance | 60F |
| High temperature tolerance | 80F |
| Ideal temperature range | 70F |
| Humidity | Moderate (50% or higher) |
| Watering requirements | Keep soil moist, water evenly; let it dry out before you water again; water daily to weekly. |
| Fertilizer requirements | Fertilize monthly when it's actively growing in the spring to summer |
| Plant food NPK | 10-10-10 |
| Days until germination | 2-3 weeks |
| Days until harvest | Not harvestable |
| Bloom time | Mid spring to fall |
| Speed of growth | Moderate |
| Hardiness zones | USDA hardiness zones 10-12 |
| Plant depth | From seeds: soil surface. From rhizome: top half visible above soil (cuttings) Crown should be even with soil surface (rhizome-less) |
| Plant spacing | 24-36 inches |
| Plant with | Coleus Impatiens Black Mondo Grass Torenia Boston Fern Silver Nickel Vine Caladium Persian Shields Fiber Optic Grass ‘Brigadoon’ St. John’s wort ‘Persian Chocolate’ moneywort Yellow corydalis |
| Don't plant with | Plants that have opposing husbandry requirements or placing them too closely. |
| Propagation method | From rhizome, seeds, cuttings, or transplants |
| Common pests | Spider mites, mealybugs, scales, snails, thrips, slugs. |
| Common diseases | Anthracnose, cercospora, bacterial leaf spot, powdery mildew, botrytis, Pythium root rot, and rhizoctonia crown rot |
| Indoor plant | Yes |
| Outdoor plant | Yes |
| Grown in container | Yes |
| Flowering plant | Yes |
| Beginner friendly | Yes |
| Care level | Minimal to none (easy) |
| Best uses | Houseplants, terrarniums, porch plant, window plant, windowsills, tabletops, desks |
What’s rex begonia?
This pretty herbaceous hybrid is a common plant that’s grown indoors.
It’s a hardy perennial that’s suited for outdoor growth only in zones 10-12. It can be grown as an annual if you’re outside of that zone.
If you want to propagate it as a perennial though, and you’re not in zones 10-12, then you’ll have to shelter it inside. But you knew that, right?
They’re known for their showy, large leaves. The blooms? Not so much. They’re tiny and most gardeners will cut them off to focus the energy on the leaves.
Rex begonias aren’t the same as other rhizomatous begonias because they have larger leaves with different husbandry.
Most of these plants have rounded, dense, teardrop leaves. They can get up to 7” wide depending on care, species, and hybrids.
They can also have long, skinnier leaves too. The leaves are metallic with silver coloration with a green, gray, or pastel hue.
The leaves are puckered with veins. There are splotches with contrasting leaf margins. There are dozens of patterns available, but the most common colors include taupe, cream, purple, pink, lavender, red, or gray.
There are over 500 different identified cultivars of rex begonia!
Types of rex begonia
There are many types of rexes to choose from. This can be the hardest part of the entire process!
But limit it to what grows in your zone, then go by color. This will narrow it down. Many hybrids look very similar to each other.
But if you don’t want to do the deep dive, check out these popular cultivars:
- Rex Tango (metallic purple foliage with silver edges, stronger leaf coloration)
- Spitfire (pink leaves with silver/green edges, 8″ tall and wide)
- Tornado (exotic, dark green leaves with silver, copper, purple)
- Yamileth (green/black leaves, silver edges)
- Ballet (silver-green leaves, mid-green edges, 8″ tall)
- Rumba (8″ tall, greenish leaves, silver variegation)
- Salsa (silver leaves with variegated green/burgundy)
- Silver Limbo (small, compact, metallic silver, purple, 5″ tall)
- Flamenco (silver green, green veins, 8″ tall)
Propagation
Rex begonia can be propagated in multiple ways. Some are easier than others. See which one works for you.
From seed
Starting from seed is difficult and takes a long time. I would suggest skipping over this if possible, unless you like a challenge.
What makes starting from seed so difficult?
The plants are hybrid, so that means that plants that germinate from saved seeds won’t grow true.
They also are extremely hard to plant because they’re tiny. Plus, they’re hard to germinate in the first place. For these reasons, you should avoid starting from seed. There are easier ways.
From cuttings
If you want to do it from cuttings, you should know that it’ll take a lot of time to do so.
You’ll need consistent effort to propagate rex begonias from leaves, but it’s possible.
This is why starting from rhizomes is the easiest recommended method. But if you’re looking for a project, perhaps this will tickle your fancy.
Propagating from leaf cuttings is often the ideal way to do it if you want to grow more of a specific cultivar or expand your species collection.
When you share cuttings, you can get different species in your garden.
To start from cuttings, snip off a leaf at the base of the stem, then remove the stem itself. Make 5 small 0.25” cuts through the main veins on the underside of the leaf.
Prep a small, shallow pot filled with high-quality soil. Pin the leaf on the surface using propagation pins. You can also DIY it and use a floss stick if you have one.
Mist the surface of the leaf. Put it somewhere warm with high humidity.
Use a plastic bag or humidity dome to preserve it. Mist it daily to keep it moist. After 6-8 weeks, you should have small plants coming out from the leaf cuts.
Move them into individual pots by gently uprooting them from the soil. It’s probably easier to wet them first so they can dislodge easily.
Repot when they’re about 3 inches tall so they have built some strong root systems.
From rhizomes
Rex begonia can be grown from rhizome cuttings. This is preferred over starting from seed because it saves time, energy, and heartbreak.
You can buy small rhizome cuttings online or get some from a friend. Check your online local groups. The rhizome must be taken from fully grown specimens.
The rhizome should have its roots and foliage already attached. You just need to use a sterilized knife to slice a piece from one end of the rhizome.
Ensure that it has no leaves, if it does, cut them off. Let it sit in a shady area for a few hours to dry out.
Get a small potter or use a seed starter kit. Fill it with a high-quality, moist, potting mix. Put the rhizome on top, then press it so the root side is below the soil line.
The top part should remain above. Put the plant in a humid area with bright, dappled sunlight.
Spritz regularly with a spray bottle. Keep it moist, but never wet. The rhizome will start growing new roots and leaves within 2-3 weeks.
Put a plastic bag over the pot. This helps keep the moisture in. Keep it at room temperature. The ideal time to root rhizomes is between late spring to summer.
This gives them time to grow before the winter, when they stop growing. They’ll have some meat on the bone, to say the least.
When they get large enough, it’s time to repot! Repot to a larger pot by tipping the plant from the potter. Brush the debris off.
Cut the leaves/roots off by removing the entire rhizome section. Repot using the same mix with the same shallow pots you’d use for other older plants. They’ll acclimate and then start growing within 2 weeks.
From transplants
When cuttings or seeds aren’t your thing, go to the nursery to buy a new plant!
This is by far the quickest method, but it’s the most expensive. You’re paying a premium to get a head start on a germinated rex begonia.
Get your container ready by finding one of the same size. Prep it with high-quality soil.
Scoop out enough soil so you can place the rhizome halfway above the soil. Firm the soil. Water gently establishes water pathways. It should drain quickly.
How to care for rex begonia
This section covers general care for rex begonia plants. You don’t need special skills to grow them. You just need to know some basics.
Hardiness zone
Rex begonias thrive in USDA hardiness zones 10-12. But this only matters for the great outdoors, not inside the house.
You can easily grow rex begonia as a houseplant even in the lower zones if conditions are good inside your house.
Many gardens in the community will grow these guys as houseplants that spend all year inside, except for the summertime when they’ll get some natural sunlight outside.
If you want the beauty of it outside, you can grow it as an annual.
But then you’ll need to be within zones 10-12. It can also be hard to provide the right amount of humidity, temperature, and watering to keep the plant thriving.
They’re also finicky about their light source. But you’ll find that the color they reward you with is worth it.
Soil
Providing a suitable substrate is the most important step in your plant’s success. Rex begonia requires a porous, peat-based medium.
Go to your local garden center in search of an African violet mix. This is suitable for rexes.
If you can’t find it, you can use a regular potting mix. Just mix it with perlite or compost to help improve the drainage.
Soil pH
Rex begonias should have a peat-based potting mix with a pH of 5.7-6.4.
They have a very fine root system that requires quick-draining soil with high-quality peat-based substrate. They like acidic soils.
Spacing
Rex begonias don’t like to crowd. They can get up to 24” wide, so provide ample spacing between plants. You should only plant one per container.
If garden sowing, provide 36” for a buffer zone. You can plant multiple if they’re not in pots.
Depth
Plant seeds on the soil surface. For rhizome-based specimens, plant the top half above the soil line. For rhizome-less ones, place the crown even with the soil line.
Sunlight
These plants will need adequate sunlight. This is one of the things that makes it difficult to grow rex begonia indoors.
They need a lot of light, but they don’t want direct light. You need to find a spot that has dappled sunlight. It should be bright, but never direct.
Use filtered or dappled light or use a grow light. If you put the plant near a sunny window, rotate the pots weekly by a quarter so it gets light equally.
If your plant grows lopsided, this is why. They can handle full or partial shade if you grow the outside. But inside, you need to give them ample light.
When transferring outside, they need some time to harden off. Give them a week of increasing light exposure.
Temperature
Rex begonias thrive in daytime temperatures around 70F and 60F by night. This will encourage your plant to grow nice and big.
During the warmer summer, you can put your rex outside. This gives them some “real” exposure to the environment, which can only be good for hardening them off! Ensure that the temperature remains above 60F at all times.
You can leave it outside overnight if the temperature is stable.
Bring them back indoors when temperatures start to hover around 60F at night or predicated cooler weather. Avoid putting it outside when it’s too hot, this can burn the plant. The low-temperature tolerance is 60F.
The high tolerance is 80F. Keep it between those two and you’re good to go.
Humidity
Keep the humidity at 50% or higher. If you notice that the leaves have yellow or brown edges, you need to humidify the environment.
You can raise it by placing your plant in the kitchen or bathroom. Or you can just put a saucer of water nearby. This should be enough to raise the humidity.
Never mist your plants directly. It can lead to mildew.
Watering
Water can help lower the temperature and increase the humidity, other than being a necessary ingredient for all plants.
Rex begonias need consistent moisture.
Water regularly, but don’t overwater. The soil should be slightly, but evenly moist. Let it dry before watering again. Don’t let it go dry or it’ll wither.
But never over water. If you notice root rot or yellow foliage, this is a sign of overwatering. This is why soil must be well-draining. Water evenly and deeply.
Never water the leaves. Only the base. Use a watering can to do it. The top 1-2” of soil should be moist, but never wet. Use a moisture meter for accuracy.
Use filtered water to avoid salt deposits or if you have hard water. Place a large saucer under the pot to help collect runoff. It also keeps the humidity up.
Plant food
Provide a balanced plant liquid fertilizer.
Use a 10-10-10 NPK ratio. Rex begonias will benefit from plant food during the spring to summer when it’s growing.
The plant should be watered before fertilizing. Avoid watering post-fertilizing because you may wash it off.
Stop fertilizing in the winter because it’ll go dormant. Use fertilizer made for houseplants only.
Growing outside
Rex begonias can be grown outside as a herbaceous perennial if you’re in USDA hardiness zones 10-12.
If you’re not in this tight zone, you should only plant it inside as a houseplant.
If planting outside, the conditions need to be right. The temperature should be stable with enough spacing.
Growing in containers
You can easily grow rex begonia in a container. These plants are rhizomatous, which means you can use a shallow container with good drainage.
The shallow container lets the soil drain water quickly. The pot should be larger than the root ball.
It does like to be rootbound, but when they start spilling over, it’s time to replant into a larger container.
Pruning
Pruning regularly is good for rex begonia because it keeps them tidy, colorful, and big. Removing leaves that are spent from the plant or debris from the soil is good practice.
This helps keep pests or pathogens off your plant. If you’re putting it outside in the warmer months, this is especially important because bugs are active during this time.
Check for pests before you bring them back inside.
Pruning is only necessary if you’re growing upright varieties of rex begonia.
Cut off the stems at the crown when the leaves are showing brown tips. Prune a few stems from the leaves to help them tidy. The tips do NOT need to be pinched. If you do, it’ll encourage branching.
Repotting
You’ll regularly want to check the rhizomes on the edges of the pot.
If the rhizomes are too wide, snip some of the rotted sections so you can propagate more plants. See the rhizome propagation section above.
Repotting will help keep the plant growing if the roots are too close together. They need to be swapped to a larger pot as they get bigger.
They’ll benefit especially when the stems are so close to the edges of the plant. This can cause the water drainage to be blocked. Choose a pot that’s 1-2 sizes bigger than the previous one.
Overwintering
Wintering Rex begonias is easy. Just bring them indoors.
Provide adequate humidity by using a container of water or putting it near a moist area. Avoid placing plants near drafts or direct sunlight. Stop fertilizing. Reduce watering.
Pests
There are quite a few pests that can get into your plant, especially during the summer months where there are a lot of them.
Calcium oxalates in the leaves and rhizomes generally repel wildlife like deer or rabbits, but they don’t do anything for common pests.
Here are some of the most common rex begonia bugs you’ll find:
Spider mites
Spider mites are tiny, microscopic bugs that pierce holes in the leaves to extract the precious water.
If there are too many of them, they can do serious damage to your plant. They’re tiny mites that feed on foliage.
They leave behind yellow dots on the surfaces. If you notice leaves wilting or dropping, it can be spider mites.
Use insecticidal soap to get rid of them. Be sure that there is enough humidity.
Mealybugs
These bugs will leave behind honeydew that turns into a sooty black mold.
If you see twisted leaves, look for eggs or visible adults. They can be removed with alcohol-dipped cotton buds. These guys will pierce the leaves of your plant, which can cause hydration problems.
Other pests include thrips, scale, snails, etc. Your basic garden pests. Reduce watering, clip spent leaves, and regularly prune your plant to help keep bugs off.
Diseases
There are a few common issues that rex begonias can get.
But if you keep humidity about 50% with well-draining soil, you should be good. Make sure there’s no water blockage, as this is a common way these plants get sick. Here are some common pathogens and how to get rid of them:
Bacterial leaf spot
This leaf spot creates lesions that look like they’re soaked with water.
The leaves will drop, but because the bacteria is inside the leaves, the dropped ones are dangerous. The bacterium can move inside the plant.
It’s especially common when temperatures are sustained over 80F. Be sure to avoid watering the leaves when you water. Ensure that the soil drains well. Keep humidity stable.
If you see leaf spot damage, you may need to dump the plant and then sanitize everything. Use a fungicide if you want to try to get rid of it. It’s much easier to start from a new plant though. So it’s up to you.
Powdery mildew
Powdery mildew is very common among house plants such as calla lilies or butterwort. These fungi thrive in humid conditions, which is why you need to keep temperatures/humidity stable. Use a cotton bud soaked in alcohol to wipe the leaves.
Root rot
Root rot is another common pathogen that’s caused by roots standing in stagnant water.
If the soil poorly drains, it’s a contributing factor to root rot. It’s drowning the root system. This is why you never overwater.
This is why you use well-draining soil. Do you see a pattern yet?
Avoid overwatering. If the soil is soggy or the leaves are turning pale, it can be a sign that root rot is taking place.
Wilting foliage is another symptom. A smelly odor is another sign. Isolate rhizomes and remove damaged roots. If you plan to replant, sterilize everything first.
Other issues you may come across include leaf spot, botrytis, southern blight, crown rot, anthracnose, cerscopora, and milew.
Companion plants
There are plenty of companions to pair rex begonia with, but you should never put them in the same pot!
They’ll compete for nutrients in the soil, so be sure to keep them separate.
Pair them with other large, single-shade leaves like pothos or silver swords. Boston ferns, parlor palms, are also excellent choices.
Some other choices include the following:
- Coleus
- Impatiens
- Black Mondo Grass
- Torenia
- Boston Fern
- Silver Nickel Vine
- Caladium
- Persian Shields
- Fiber Optic Grass
- ‘Brigadoon’ St. John’s wort
- ‘Persian Chocolate’ moneywort
- Yellow corydalis
Don’t plant with
You can pretty much pair your rex begonia with anything. Just don’t put them in the same pot. If you’re growing it outside, provide plenty of space between the begonia and other plants.
Best uses
Rex begonia can be used as a decorative piece. They’re commonly placed on windowsills, patios, or decks.
They can be used throughout the season in the summer, then again in the winter indoors.
They can be used in hanging baskets or even in the bathroom! These guys can be put anywhere that needs a bit of color.
Double that for bathrooms or rooms with high humidity. If you need to add a splash of color, rex begonia has your back.
While they can be stubborn, they just need the RIGHT degree of TLC.
Enjoy your rex begonia
Now that you know the basics of how to grow and care for rex begonia, go for it! These plants are rewarding, even if they’re slightly temperamental with their temperature requirements.
They can be presented on your porch for a nice splash of color. Or just put on your coffee table for a conversation piece.
How do you plan to use yours?
Further reading
Check out these other references you may find useful:
I’ve always been interested in gardening, but I never took it seriously until I was forcefully gifted an orchid. This was what got me into the hobby and I’ve never looked back. I enjoy writing about it, but not nearly as much as getting into the dirt and sculpting the perfect decorative ornamental to enjoy for the times.