Flowers & bulbs

How to Grow Wax Begonias: Planting, Care & Bloom

Quick answer

Clemson: start seed about 12 weeks before planting outdoors; set plants after frost danger is past. Space wax begonias 6 to 8 inches apart; Clemson also lists 12 inches for general bedding begonias — label that separately. Bronze-leaved types handle full sun better.

Wax begonias at a glance

PlantStart indoors: 12 wk before last frost; Transplant: last frost
SunWax-specific: not restricted to partial shade — can grow in full sun; bronze-leaved types handle sun better than green-leaved (green prefer morning sun / afternoon shade to prevent sunscald).
Waterdo not water when hot sun hits foliage (scorch); drip/soaker or early morning watering reduces fungal disease.
SpacingClemson wax: set plants 6 to 8 inches apart after frost.
Days to bloomBloom season June–Sept. (Purdue HO-80)
-13-12-11-10-9-8-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Updated

Scope: fibrous wax begonias (Begonia × semperflorens-cultorum) only — not tuberous, rex, angel-wing, or hardy begonia.

Wax begonias in bloom
Wax begonias (Begonia × semperflorens-cultorum). Photo: Dietmar Rabich, Wikimedia Commons, CC BY-SA 4.0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Clemson: start seed about 12 weeks before planting outdoors; set plants “after the danger of frost is past.” (Clemson HGIC)

Depth and spacing

Clemson wax: set plants 6 to 8 inches apart after frost. The same Clemson page also says 12 inches apart for a general bedding effect — that 12-inch figure is for bedding begonias broadly; prefer 6–8 inches for wax with that source label. Stem cuttings in spring or fall also start plants (Clemson). Height: most begonias 8 inches to 2 feet depending on type; wax are compact bushy bedding plants.

Sun, soil and water

Clemson general: partial shade, moist well-drained organic soil. Wax-specific: not restricted to partial shade — can grow in full sun; bronze-leaved types handle sun better than green-leaved (green prefer morning sun / afternoon shade to prevent sunscald). Drought and heat tolerance better than many other begonias; still prefer moist fertile well-drained soil. Water: do not water when hot sun hits foliage (scorch); drip/soaker or early morning watering reduces fungal disease.

Care and bloom

Continuous summer flowering (Clemson wax). Deer and rabbit resistant (Clemson). Use in beds, window boxes, hanging baskets, containers. Sensitive to insecticidal soaps — test small area (Clemson). Purdue: June–September bloom.

Pests and diseases (organic)

Snails and slugs: Clemson major pests. UC IPM: handpick at night; iron phosphate bait — follow label. (UC IPM)

Mealybugs, spider mites, thrips, scales: Clemson lists these. Cultural: inspect; water spray for mites; avoid soap sprays without testing (sensitivity).

Diseases: Clemson Botrytis blight and stem rot, powdery mildew, Pythium root and stem rot. Cultural: morning water, drainage, air flow, avoid wetting foliage in sun/heat. Viruses (INSV, TSWV via thrips): remove infected plants (Clemson).

Related: /planting/petunia/ · ZIP planner · organic pest control

Frequently asked questions

When do I plant wax begonias outside?

After frost danger (Clemson)

Sun or shade?

Wax can take full sun, especially bronze foliage; green foliage prefers morning sun / afternoon shade (Clemson).

How far apart?

About 6 to 8 inches for wax set-outs (Clemson). Clemson’s 12-inch figure is for bedding begonias generally — label it separately.

Sources