Ornamental · Begoniaceae
Wax Begonia
Begonia semperflorens
With moist soil, dappled light, and a little breathing space, the wax begonia carries color across the garden from spring to frost.
Partial shade
Every 2–4 days
50–75°F · 10–24°C
USDA 9–11
Overview
The wax begonia has long been a designer's shortcut to effortless summer color. Its thick, glossy leaves, in green or deep bronze, read as tidy and considered whether they edge a formal border or soften a casual porch. Small pink, red, or white flowers keep arriving from spring to the first hard frost, so a planting never looks tired.
Think of it as a warm-season annual with a designer's flexibility. It is a tender perennial at heart, holding over only in the mildest zones, so most homes replant it each spring and clear it at frost, a rhythm that suits a garden meant to be refreshed. Staying low and neat under a foot, it works as tidily in a bedding scheme as it does in a grouping of pots by the door.
Where it truly earns its place is the shaded corner most flowers refuse to fill. Bronze-leaved kinds hold their own in more sun and green-leaved ones prefer afternoon shade, and both bloom without the daily chore of deadheading that a busy household rarely has time for. Keep the soil evenly moist and well drained, and it settles into a low-maintenance routine.
Care
The short version: dappled light or morning sun with afternoon shade, soil kept evenly moist but never soggy, a monthly feed through the season, and 6 to 12 inches of space between plants so air moves freely.
Light
Wax begonias look their best in partial shade or morning sun with afternoon shade, though they adapt to a wide range of settings. Bronze-leaved types hold up to full sun, which suits an open bed, while green-leaved ones prefer a spot shaded through the hot part of the day.
Water
Keep the soil evenly moist but well drained, watering every 2 to 4 days as the surface dries. Water at the base early in the morning, since foliage left wet under hot sun can scorch and damp leaves invite fungal disease. The thick waxy leaves give a little grace, letting the plant ride out a brief dry spell between waterings.
Soil
Plant it in moist, well-drained soil rich in organic matter. A slightly acidic pH of 5.5 to 6.5 suits it, and drainage is the detail that matters most, since soggy ground is what rots the roots.
Temperature
This plant is happiest in mild conditions, between 50°F and 75°F (10°C to 24°C). It fades in real heat and dies back at the first frost, which is why it plays the part of an annual in most gardens.
Humidity
Ordinary outdoor air suits it, so there is no humidity level to manage. Airflow is the thing to design for, because crowded, humid plantings are exactly where mildew and gray mold settle in.
Feeding
Feed monthly through the growing season with a balanced fertilizer made for flowering bedding plants. That light, steady feeding keeps a planting in bloom without pushing the soft, floppy growth that spoils its neat look.
Pruning
Pinch or shear any leggy stems to keep the plant compact and full and to draw out fresh branches. The flowers are self-cleaning, so a planting stays presentable without the deadheading most annuals ask for.
Size & spacing
These stay low and tidy, 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 moves freely between plants and disease has less of a foothold.
When to plant
This is a plant built for the warm months, with no patience for frost. Start the dust-fine seed indoors in late winter, move the young plants outdoors only after the last frost and once nights hold above 50°F (10°C), and the display carries on without pause from early summer until frost closes the season.
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
Nearly every wax begonia setback comes down to moisture lingering where it should not, on the leaves or around the roots. Notice it early and a planting is easily brought back with better spacing and a lighter hand on the watering can. Match what you see below, then step in before it spreads.
A wilting plant with soft, blackened stems at the soil line
A plant that collapses in wet soil points to stem or Pythium root rot, the result of ground that never drains. The crown and roots turn soft, dark, and decayed, past saving. Lift the worst plants, correct the drainage, and pull back on watering before the rot travels.
Fix:
- Remove severely affected plants
- Improve soil drainage
- Reduce watering frequency
White powdery dust settling over the leaves and stems
That dusty veil is powdery mildew, a fungus that takes hold when the air turns humid and still. It rubs off at first but soon runs through a crowded planting. Give the plants 6 to 12 inches of room, clear away the worst leaves, and water at the base in the morning so the foliage dries quickly.
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 is botrytis blight, or gray mold, which arrives in cool, damp, still weather. The tissue turns tan to brown and takes on a coat of gray spores. Trim out the infected parts, open the planting for better airflow, and keep water off the leaves to bring it under control.
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 mark mealybugs, while slender crawling specks are usually thrips, and both feed on the stems and leaf undersides. Thrips do the deeper damage, since they can carry viruses such as INSV and TSWV. Rinse off light infestations, treat the rest with insecticidal soap, and cut out any heavily infested growth.
Fix:
- Spray off light infestations with water
- Treat with insecticidal soap
- Remove heavily infested plant parts
Toxicity
For all its easy charm, this is not a plant to leave within a pet's reach. Every part holds calcium oxalate crystals, most of all the roots, and a bite leaves the mouth burning and sore. Site it away from cats, dogs, horses, and grazing animals, and keep in mind that no part is safe for people to eat.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
A cat that chews the leaves or roots takes in a mouthful of sharp oxalate crystals, so watch for heavy drooling, pawing at the mouth, and vomiting. The roots hold the most and cause the sharpest burning.
Dogs Toxic
Dogs that dig up and gnaw the roots come off worst. 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 drooling, mouth pain, and colic-like discomfort. A grazing animal that takes in a large amount faces the steepest risk.
Rabbits Toxic
The oxalate crystals burn a rabbit's mouth and digestive tract as they do other animals, so keep the plant well out of reach rather than offering any as forage.
Livestock Toxic
Cattle, goats, and sheep grazing on begonia can take in enough oxalate to bring on mouth irritation, drooling, and digestive upset, and a large helping is the real danger.
Birds Caution
Solid data on birds is thin, but the crystals that burn other animals would irritate a curious bird's mouth too, so treat the plant as off limits to be safe.
People Caution
No part of the wax begonia is meant to be eaten, and a bite leaves the mouth burning. Handling the sap can irritate sensitive skin, so wash up after pruning and keep it 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
Wax begonias come to the garden mostly as named series rather than single cultivars, grouped by leaf color and by how much sun they take. These are the ones a planting scheme most often calls for.
Cocktail Series
A compact, bronze-leaved group, with selections such as 'Whiskey', 'Vodka', and 'Gin', that takes full sun better than most wax begonias.
Ambassador Series
Green-leaved and bred for heat, these settle in best with morning sun and shade through the hot afternoon.
Doublet Series
This series carries full, double, rose-like blooms in place of the plain single flowers most wax begonias show.
How to propagate
Stem cuttingsEasy
Spring or fall, including from overwintered plants · Roots typically form in about 2 to 4 weeks
Cuttings are the simplest route, taken in spring or fall, even from a plant carried through winter indoors. Snip a healthy stem, or lift a single leaf, and set it into a moist, well-drained medium. Roots form in about 2 to 4 weeks, giving 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 calls for more patience. Start it indoors 8 to 12 weeks before the last frost, scatter the dust-fine seed over the surface without covering it, and give it gentle bottom heat. It takes several weeks to reach transplant size, so it never goes straight into the garden.
Myths
Wax begonias insist on full shade and cannot take the sun.
Given time to settle, these plants take a wide range of light in stride. Bronze-leaved cultivars grow and flower well in full sun, while the green-leaved types are the ones that ask for afternoon shade.
A pet nibbling a begonia is nothing to worry about.
Every part carries calcium oxalate crystals, and the roots carry the most. A single bite burns the mouth and brings on drooling and vomiting in cats, dogs, and horses, so keep curious pets clear of the plant.