Ornamental · Begoniaceae
Wax Begonia
Begonia semperflorens
Give it moist soil, dappled light, and a little breathing room, and this easygoing begonia rewards you with blooms from spring right through to frost.
Partial shade
Every 2–4 days
50–75°F · 10–24°C
USDA 9–11
Overview
You can relax with this one. The wax begonia takes its name from thick, glossy leaves that feel almost polished, in soft green or deep bronze, and it ranks among the most forgiving flowering plants a beginner can grow. That is why you see it filling summer beds, borders, and window boxes, where its small pink, red, or white flowers keep appearing from spring until the first hard frost.
Most gardeners simply enjoy it as a warm-season annual. At heart it is a tender perennial that lives year-round only in the mildest zones, so nearly everywhere else you plant it fresh each spring and let it go at frost, and there is nothing to feel bad about there. It stays neat and low, rarely reaching more than a foot, and it looks just as lovely massed in a bed as it does tucked into a favorite pot.
Here is the reassuring part: it thrives in the shady corner where fussier flowers sulk. Bronze-leaved kinds happily take more sun and green-leaved kinds prefer afternoon shade, and both bloom without any deadheading from you. Keep the soil evenly moist and well drained, and the plant will handle nearly everything else on its own.
Care
The short version: give it dappled light or morning sun with afternoon shade, keep the soil evenly moist but never soggy, feed it once a month through the season, and leave 6 to 12 inches of space between plants so the air can move freely.
Light
Wax begonias are happiest in partial shade or morning sun with afternoon shade, though they forgive a wide range of light. The bronze-leaved types can take full sun the best, while the green-leaved ones may scorch in it and will thank you for shade through the hottest part of the day.
Water
Aim to keep the soil evenly moist but well drained, watering about every 2 to 4 days as the top starts to dry. Water at the base early in the morning, since leaves left wet under hot sun can scorch and damp foliage invites fungal disease. If you slip up now and then, those thick waxy leaves let the plant coast through a brief dry spell.
Soil
Give it moist, well-drained soil rich in organic matter. A slightly acidic pH of 5.5 to 6.5 suits it nicely, and good drainage matters more than anything else, because it is soggy ground that rots the roots.
Temperature
This plant likes things mild, somewhere between 50°F and 75°F (10°C to 24°C). It tends to sulk in real heat and dies back at the first frost, which is simply why most gardeners grow it as an annual.
Humidity
Ordinary outdoor humidity is plenty, so there is no target number to worry about. What matters far more is airflow, since crowded, humid plantings are exactly where mildew and gray mold like to settle in.
Feeding
Feed once a month through the growing season with a balanced fertilizer made for flowering bedding plants. That gentle, steady feeding keeps the blooms coming without pushing out soft, floppy growth.
Pruning
If any stems grow leggy, pinch or shear them back to keep the plant compact and bushy and to coax out fresh branches. The flowers are self-cleaning, so you can happily skip the deadheading that so many annuals ask for.
Size & spacing
These stay pleasantly small, reaching 6 to 12 inches (15 to 30 cm) tall and about as wide. Set them 6 to 12 inches (15 to 30 cm) apart so air can move freely between them and disease finds far less of a foothold.
When to plant
Wax begonias are tender, so they have no patience for frost, but the timing is easy to get right. Start the dust-fine seed indoors in late winter, wait to set the young plants out until after the last frost and once nights stay above 50°F (10°C), and from there they bloom happily from early summer until frost finally stops them.
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
Take heart, because nearly every wax begonia trouble comes down to one thing: too much moisture sitting on the leaves or around the roots. Notice the early signs and you can usually turn things around with better spacing and a little care with watering. Find what matches your plant below, then step in before it spreads.
A wilting plant with soft, blackened stems at the soil line
When a plant flops even though the soil is wet, the likely cause is stem or Pythium root rot from ground that never drains. The crown and roots go soft, dark, and decayed, and sadly those plants cannot be saved. Lift the worst ones, improve the drainage, and ease back on watering before the rot reaches its neighbors.
Fix:
- Remove severely affected plants
- Improve soil drainage
- Reduce watering frequency
A dusty white coating spreading over the leaves and stems
That soft, dusty film is powdery mildew, a fungus that moves in when the air turns humid and still. It wipes off easily at first, but it soon travels through crowded plantings, so do not wait. Give the plants 6 to 12 inches of space, take off the worst leaves, and water at the base in the morning so the foliage can stay 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 as they rot and collapse
This one is botrytis blight, sometimes called gray mold, and it settles in during cool, damp, still weather. The affected tissue turns tan to brown and ends up dusted with gray spores. Trim away the infected parts, open the planting up for better airflow, and keep water off the leaves, and the plant can recover.
Fix:
- Remove and discard infected plant parts
- Increase air circulation
- Avoid overhead watering
Cottony clumps or tiny insects with stippled, distorted growth
Cottony white masses usually mean mealybugs, while slender crawling specks are more likely thrips, and both feed on the stems and leaf undersides. Thrips do the more lasting damage, since they can carry viruses such as INSV and TSWV. Rinse off light infestations, treat what is left with insecticidal soap, and snip away any heavily infested growth.
Fix:
- Spray off light infestations with water
- Treat with insecticidal soap
- Remove heavily infested plant parts
Toxicity
This is the one place to be firm: it is not a plant for pets to chew. Every part holds calcium oxalate crystals, with the most tucked into the roots, and a bite will leave the mouth burning, drooling, and sore. Keep it out of reach of cats, dogs, horses, and grazing animals, and remember that no part is 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 ends up with a mouthful of sharp oxalate crystals, so watch for heavy drooling, pawing at the mouth, and vomiting. The roots hold the most crystals and cause the worst burning.
Dogs Toxic
Dogs that dig up and gnaw the roots tend to suffer the most. Look for intense mouth burning, heavy salivation, repeated vomiting, and clear trouble swallowing soon after a bite.
Horses Toxic
The same oxalate crystals irritate a horse's mouth and gut, bringing on drooling, mouth pain, and colic-like discomfort. A grazing animal that eats a large amount faces the steepest risk of all.
Rabbits Toxic
Those oxalate crystals burn a rabbit's mouth and digestive tract just as they do with other animals, so keep the plant well out of reach rather than ever offering it as forage.
Livestock Toxic
Cattle, goats, and sheep that graze on begonia can take in enough oxalate to trigger mouth irritation, drooling, and digestive upset, and it is a big helping that poses the real danger.
Birds Caution
Firm data on birds is thin, but the crystals that burn other animals would irritate a curious bird's mouth too, so it is safest to 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 bother sensitive skin as well, so wash up after pruning and keep the plant away from small children.
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 will usually find wax begonias sold as named series rather than single cultivars, grouped by their leaf color and how much sun they can take. These are the ones you are most likely to come across.
Cocktail Series
A compact, bronze-leaved group with selections named 'Whiskey', 'Vodka', and 'Gin' that stand up to full sun better than most wax begonias.
Ambassador Series
Green-leaved and bred to handle heat, these do their best with morning sun and shade through the hot afternoon.
Doublet Series
This one carries full, double, rose-like blooms in place of the plain single flowers most wax begonias produce.
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, reassuring route, and you can take them in spring or fall, even from a plant you carried through the winter indoors. Snip a healthy stem, or gently pull a single leaf, and settle it into a moist, well-drained medium. Roots form in about 2 to 4 weeks, growing into 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 asks for a bit more patience. Start it indoors 8 to 12 weeks before your last frost, scatter the dust-fine seed over the surface without covering it, and give it gentle bottom heat. It needs several weeks to reach transplant size, so it never goes straight out into the garden.
Myths
Wax begonias must have full shade and cannot handle any sun at all.
Once they have settled in, these plants cope with a surprisingly wide range of light. Bronze-leaved cultivars grow and flower beautifully in full sun, while the green-leaved types are the ones that appreciate a little afternoon shade.
A begonia is harmless if a pet takes a small nibble.
Every part carries calcium oxalate crystals, and the roots carry the most of all. A single bite can burn the mouth and bring on drooling and vomiting in cats, dogs, and horses, so keep curious pets well away from the plant.