Ornamental · Begoniaceae
Wax Begonia
Begonia semperflorens
Give it moist soil, dappled light, and a bit of elbow room, and it'll bloom nonstop from spring right up to frost.
Partial shade
Every 2–4 days
50–75°F · 10–24°C
USDA 9–11
Overview
Ever wonder where the name comes from? It's those thick, glossy leaves that look almost polished, in green or deep bronze. This is about as easy as flowering plants get, which is why you'll spot it in so many summer beds, borders, and window boxes. The little pink, red, or white flowers just keep coming from spring until the first hard frost.
Most folks grow it as a warm-season annual. It's really a tender perennial, but it only makes it through winter in the mildest zones, so pretty much everywhere else you plant it fresh in spring and let it go once frost hits. It stays low and tidy, rarely more than a foot tall, and it looks great whether it's massed in a bed or sitting in a pot.
Here's the best part: it's happy in the shady spot where other flowers just won't cooperate. Bronze-leaved kinds take more sun, green-leaved ones want afternoon shade, and neither one asks you to deadhead. Keep the soil evenly moist and well drained, and honestly the plant handles most of the rest.
Care
The short version: dappled light or morning sun with afternoon shade, soil that stays evenly moist but never soggy, a monthly feed through the season, and 6 to 12 inches of space between plants so the air keeps moving.
Light
Wax begonias are happiest in partial shade or morning sun with afternoon shade, but they'll put up with a lot. The bronze-leaved types handle full sun the best, while the green-leaved ones scorch in it and really want shade through the hottest part of the day.
Water
Keep the soil evenly moist but well drained, watering every 2 to 4 days as it starts to dry out. Water at the base early in the morning, since leaves left wet under hot sun can scorch and damp foliage just invites fungal trouble. And if you forget once in a while? Those thick waxy leaves let it coast through a short dry spell.
Soil
Plant it in moist, well-drained soil rich in organic matter. A slightly acidic pH of 5.5 to 6.5 is ideal, but honestly good drainage matters most, because soggy ground is what rots the roots.
Temperature
It likes things mild, somewhere around 50°F and 75°F (10°C to 24°C). It gets sulky in real heat and dies back at the first frost, which is exactly why most people just grow it as an annual.
Humidity
Regular outdoor humidity is plenty, so there's no magic number to chase. What really counts is airflow, because crowded, humid plantings are where mildew and gray mold love to move in.
Feeding
Feed it monthly through the growing season with a balanced fertilizer meant for flowering bedding plants. That easy, steady feeding keeps the blooms coming without pushing out soft, floppy growth.
Pruning
If a stem gets leggy, just pinch or shear it back to keep the plant compact and bushy and to nudge out new branches. The flowers clean up after themselves, so you can skip the deadheading most annuals demand.
Size & spacing
These stay nice and small, about 6 to 12 inches (15 to 30 cm) tall and roughly as wide. Space them 6 to 12 inches (15 to 30 cm) apart so air moves between them and disease has a harder time getting a grip.
When to plant
Wax begonias are tender, so frost is a hard no. Start that dust-fine seed indoors in late winter, wait to move the young plants outside until after the last frost and once nights stay above 50°F (10°C), and then they'll bloom without a break from early summer until frost shuts things down.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: About 8 to 12 weeks before the last spring frost; do not cover the tiny seed.
- Plant: After all danger of frost has passed and night temperatures stay above 50°F.
- Harvest: Blooms continuously from spring or early summer until frost.
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Here's the good news: almost every wax begonia problem comes back to too much moisture, either on the leaves or down around the roots. Spot it early and you can usually fix it with better spacing and a smarter watering routine. Find what matches your plant below, then jump on it before it spreads.
A wilting plant with mushy, blackened stems at the soil line
When a plant flops even though the soil's wet, that's usually stem or Pythium root rot from ground that just won't drain. The crown and roots go soft, dark, and mushy, and sadly those plants are done for. Pull the worst ones, sort out the drainage, and ease off the watering before it spreads to the neighbors.
Fix:
- Remove severely affected plants
- Improve soil drainage
- Reduce watering frequency
A dusty white film creeping over the leaves and stems
That dusty film? It's powdery mildew, a fungus that shows up when the air's humid and still. It'll wipe off at first, but it spreads fast through crowded plantings, so don't sit on it. Give the plants 6 to 12 inches of room, pull the worst leaves, and water at the base in the morning so the foliage stays dry.
Fix:
- Improve spacing and air circulation
- Remove affected foliage
- Water at the base in the morning rather than overhead
Gray fuzz on the flowers that rot and flop over
This one's botrytis blight, also called gray mold, and it moves in during cool, damp, still weather. The tissue turns tan to brown and ends up covered in gray spores. Cut off the infected bits, open the planting up for better airflow, and keep water off the leaves, and it'll usually settle down.
Fix:
- Remove and discard infected plant parts
- Increase air circulation
- Avoid overhead watering
Cottony clumps or tiny insects with stippled, distorted growth
Cottony white blobs usually mean mealybugs, while skinny crawling specks are probably thrips, and both feed on the stems and leaf undersides. Thrips are the bigger worry, since they can carry viruses like INSV and TSWV. Hose off the light stuff, treat what's left with insecticidal soap, and cut away anything that's badly infested.
Fix:
- Spray off light infestations with water
- Treat with insecticidal soap
- Remove heavily infested plant parts
Toxicity
This is where you'll want to be careful, because it's not a plant for pets to chew. Every part holds calcium oxalate crystals, and the roots hold the most, so a bite leaves the mouth burning, drooling, and sore. Keep it away from cats, dogs, horses, and grazing animals, and no, it's not safe for people to eat either.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
If a cat chews the leaves or roots, it gets a mouthful of sharp oxalate crystals, so keep an eye out for heavy drooling, pawing at the mouth, and vomiting. The roots hold the most, and they cause the worst burning.
Dogs Toxic
Dogs that dig up and gnaw the roots usually have it worst. You'll see intense mouth burning, heavy drooling, repeated vomiting, and obvious trouble swallowing pretty soon after a bite.
Horses Toxic
Those same oxalate crystals irritate a horse's mouth and gut, so expect drooling, mouth pain, and colic-like discomfort. A grazing animal that eats a big amount is the one at the steepest risk.
Rabbits Toxic
The oxalate crystals burn a rabbit's mouth and digestive tract just like they do everyone else's, so keep the plant well out of reach and don't ever offer it as forage.
Livestock Toxic
Cattle, goats, and sheep that graze on begonia can take in enough oxalate to bring on mouth irritation, drooling, and digestive upset, and it's a big helping that's the real danger.
Birds Caution
There isn't much solid data on birds, but the crystals that burn other animals would bother a curious bird's mouth too, so it's safest to just treat the plant as off limits.
People Caution
No part of the wax begonia is meant to be eaten, and a bite leaves the mouth burning. Handling the sap can bug sensitive skin too, so wash up after pruning and keep it away from little kids.
Toxicity is oral and gastrointestinal irritation rather than systemic in pets; grazing animals eating large amounts are at greater risk.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
You'll mostly find wax begonias sold as named series rather than one-off cultivars, sorted by leaf color and how much sun they'll take. These are the ones you're most likely to run into.
Cocktail Series
A compact, bronze-leaved bunch with names like 'Whiskey', 'Vodka', and 'Gin' that handle full sun better than most wax begonias do.
Ambassador Series
These are green-leaved and bred for heat, and they do best with morning sun and some shade through the hot afternoon.
Doublet Series
This one's got full, double, rose-like blooms instead of the plain single flowers you'll see on most wax begonias.
How to propagate
Stem cuttingsEasy
Spring or fall, including from overwintered plants · Roots typically form in about 2 to 4 weeks
Cuttings are the easy way to go, and you can take them in spring or fall, even from a plant you kept going through winter indoors. Snip a healthy stem, or just pull off a single leaf, and pop it into a moist, well-drained medium. Roots form in about 2 to 4 weeks, and you'll get a plant that matches its parent.
SeedModerate
Indoors about 8 to 12 weeks before the last frost · Several weeks from sowing to transplant size
Seed takes a bit more patience. Start it indoors 8 to 12 weeks before your last frost, scatter that dust-fine seed on the surface without covering it, and give it gentle bottom heat. It needs several weeks to hit transplant size, so it never goes straight out into the garden.
Myths
Wax begonias have to have full shade and can't take any sun.
Once they've settled in, these plants deal with a pretty wide range of light. Bronze-leaved cultivars grow and flower just fine in full sun, and it's really the green-leaved types that want a little afternoon shade.
A little nibble of begonia won't bother a pet.
Every part has calcium oxalate crystals, and the roots have the most. One bite burns the mouth and brings on drooling and vomiting in cats, dogs, and horses, so it's smart to keep curious pets away from the plant.