Known botanically as Begonia semperflorens, begonias are tender perennials grown as annuals in areas with freezing winter temperatures. They only grow about nine inches high, so they are often used as border plants in flower beds. Begonias grow in either full sun or partial shade. The plants produce seeds but they are very difficult to start from seed. Since they are so popular, they are available everywhere in early spring as small bedding plants. They grow equally well in the garden, in container gardens, or in hanging baskets.
Plant begonias in full sun to partial shade. They will produce flowers either way, but flower production will be less in shade than in sun. Begonias like rich, loose soil that is well-drained, and where water does not stand too long after a rain.
Prepare the planting bed. Add 2 inches of peat moss, 1 inch of sand and 1 inch of compost to the surface of the soil in the planting bed. Turn over the soil using a spade, digging down the depth of the spade. Smooth the soil with a garden rake when finished.
Plant begonias from transplants. They are widely available in springtime, in colors ranging from white to yellow to pink to red. Use your garden trowel to dig a small hole slightly larger than the size of the starter pot the begonias came in. Pop the roots into the hole, then back fill with soil. Firm the surface of the soil gently with your hands so the little plant stands up on its own. Space the transplants 6 to 8 inches apart in all directions for a mass of color.
Water the transplants individually with a hand watering can after the bed is completely planted. Continue to provide begonias with the equivalent of an inch of rainfall per week.
Mulch the planting bed with 2 inches of shredded leaves or hay. Begonias will quickly grow to completely hide the soil, but a mulch is helpful in early spring when they’re still small and vulnerable to competition from weeds.
Fertilize begonias weekly using a water-soluble fertilizer sprayed directly on the foliage with a hose-end sprayer. Mix the fertilizer in the spray-attachment, following the recommendations of the manufacturers of both the fertilizer and the sprayer. Spray the plants with the fertilizer mixture in early morning, before the sun gets too high in the sky.
Begonias can be potted up and overwintered indoors. Dig up and plant half a dozen plants in an 8-inch pot. Cut the plants back by half of their size and place in a south-facing window. They will acclimate themselves and begin growing in a few weeks. Move them back outdoors when all danger of frost has passed.
Copyright Sharon Sweeny, 2011