Plant In The Right Place
Wax begonias are tender perennials ( we are treating them as annuals) and will not survive frost. Do not move seedlings to the garden until night temperatures remain above 50°F.
Light – Begonias do best in light shade but will tolerate deep shade, although they may become leggy and will not bloom as vigorously. They will also grow in full sun if the soil is kept moist. Many of the new heat-resistant hybrids are quite tolerant of sunny situations, especially in areas with cool summers. Wax begonias prefer 65°F nights and 75°F to 85°F days in summer. Indoors, grow them in a south-facing window in winter for best blooming.
Soil – Begonias like rich, well-drained soil with a pH range of 6 to 8.
Planting Wax Begonias
Plants From The Garden Center – Because wax begonias take so long to grow from seed, most yardeners prefer to purchase them as bedding plants from the garden center. Do not move begonias to the garden until nighttime temperatures stay above 50°F. Space transplant seedlings 8 to 10 inches apart. For planting tools see Hand Tools For Digging and Planting in Yardener’s Tool Shed.
Growing From Seed - Wax begonia seed must be sown indoors four to six months before the last spring frost date. Sow the very fine, almost powder-like seeds in a sterile growing mix and water the plants from below to avoid problems with damping-off, a fungal disease. Press the seeds in the soil but do not cover them with soil; they require light to germinate. Cover the seed flat with glass or plastic to maintain high humidity. Allow 14 to 20 days for germination. Soil temperatures between 70° and 75°F are ideal. For seed starting supplies see Seed Starting Supplies and Equipment in Yardener’s Tool Shed.
Wax begonias are easy to propagate by softwood cuttings. Take cuttings from plants brought indoors for winter bloom and root them to produce spring transplants. See the Plant Propagation Equipment section of Yardener’s Tool Shed.