Color up your shade garden with begonias

With all the talk of downy mildew on impatiens, gardeners are searching for alternatives to brighten their shade gardens. Although nothing can really match the colorful show of Impatiens walleriana, begonias come pretty close.

There are a few key types of begonias grown in our area: Rex, tuberous and semperflorens (wax) begonias. Rex begonias are tropical plants chosen for their brightly patterned and uniquely shaped leaves. Tuberous begonias are heavily blooming, attractive plants suitable for containers, window boxes, hanging baskets and garden beds. Their blooms might be single or double, simple or ruffled and come in shades of white, pink, red, orange, yellow or combinations of those. Wax begonias are popular bedding and container plants. Small but plentiful, flowers bloom in pink, red and white against glossy green or bronze rounded leaves.

Wax begonias

Wax begonias are most commonly grown as bedding plants. They are easy to grow, require little maintenance and bloom profusely from spring to fall. Plant wax begonias in the garden in well-drained soil rich with organic matter, spaced 8 to 12 inches apart. Use them in mass planting or to edge a border.

In containers, they combine beautifully with other shade-loving annuals. My window boxes have hosted wax begonias with ferns, coleus, caladium and variegated ivy trailing over the edge.

Fertilize wax begonias with a balanced slow-release fertilizer when planting or once a month with a quick-release fertilizer. Wax begonias rarely are bothered by insects or disease.

The Harmony series features white, pink or red begonias with bronze foliage. Plants in the Prelude series have green leaves. Both deliver the same outstanding performance.

Rex begonias

Rex begonias can be planted in the garden, but I think they are best used in containers, where their foliage can be appreciated up close. Plant them in a light potting mix. Don't use one with moisture-holding crystals, and let the soil dry out between waterings.

The flowers of rex begonias are small and often inconsequential. Choose a rex begonia for its leaves that showcase vibrant colors and distinctive patterns. Red Tango sports heart-shaped leaves with burgundy centers framed by a wide pink band, a thin line of silver and then edged in dark green. Fedor shows off creamy white leaves with maroon veins.

Rex begonias are best planted in bright but indirect light. Too much light will burn leaves, but some light is needed to keep the brilliant coloring.

Tuberous begonias

Tuberous begonias offer the showiest flowers. Brightly colored petals in shades of white, yellow, pink and red are arranged in single or double flowers, some with ruffled edges. Their foliage can be chocolate brown or light to dark green. Some types grow in clumps; some have trailing stems.

In the garden, plant tuberous begonias in moist, well-drained soil in partial shade. Space them from 6 to 12 inches apart. Be sure to set them in the ground at the same depth they were in their growing pots. Planting them too deep might cause stems to rot. They will need supplemental watering during dry spells, but do not overwater. Fertilize them every two weeks during the growing season with a diluted balanced fertilizer.

Plant tuberous begonias in containers with a light potting mix. Use a slow-release fertilizer at the time of planting. Allow the soil to dry before watering. Place containers in a spot sheltered from strong winds, and remove spent blooms to encourage a steady abundance of new flowers.

Blitz offers yellow flowers; Clara sports fully double, pure white flowers; Janny Fringed is a lovely bicolor variety with double, rose-margined, creamy yellow flowers.

The best for last

My favorite begonias, and ones I wouldn't go a season without, are the Dragon Wing and Whopper types. They are tough plants that bloom without fail - in shades of white, pink or red - over shiny, almost indestructible green or bronze foliage. They grow quickly, require little maintenance and are drought resistant. They do not need deadheading and rarely are bothered by pests or disease.

Dragon Wing begonias grow 15 to 18 inches tall and wide. Whopper begonias grow even larger.

If you've decided to forego planting impatiens this year, don't give up on color in the shade. Remember what they say, "When one garden gate closes, another one opens." Give begonias a try - you might just find a new favorite plant.

• Diana Stoll is a horticulturist and the garden center manager at The Planter's Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040, ext. 2 or visit planterspalette.com.