Cultural Problems on Begonias

Light Problems

• Though begonias need sunlight like other plants, too much light can cause bleaching of the leaves. Indirect light is best for begonia plants. If southwestern exposure produces bleaching on outdoor begonia plants, move the plants to a different area. Morning sun with some afternoon shade is best for begonia plants.

Watering Problems

• Outdoors, begonias need weekly watering during dry periods. Plants in containers need more frequent watering. Indoors, these plants can often suffer from overwatering. Allow the soil to dry out in between waterings, then irrigate plants until water runs out from the bottom of the pot. Place begonia plants on pebbles on trays of water to keep roots from staying wet and provide humidity. Though begonias dislike wet roots, they do prefer some humidity above ground.

Fertilizer Problems

• Fertilize outdoor begonias with a diluted all-purpose fertilizer every two weeks. Do not overfertilize, which can burn roots. Indoors, fertilize begonia plants weekly with a balanced fertilizer used at one-quarter strength.

Deadheading Problems

• When blooms fade, remove them from the plant to encourage more flowers to bud. Leaving the dead flowers on the plant gives it a bad appearance and saps the energy that should go to new flower production.

Temperature Problems

• Most types of begonias cannot withstand cold temperatures of Northern winters. Container plants should be brought indoors for the winter. Tuberous varieties of begonia are generally dug up in the fall and kept in a dry peat mixture in a garage or basement at around 45 degrees Fahrenheit. Repot in the spring, water and fertilize biweekly.

Pest Problems

• Begonia plants can develop problems with powdery mildew, a whitish substance caused by fungus growth. Spray on a commercial fungicide to keep the growth from spreading to other plants. Aphids, whiteflies, spider mites, thrips and mealybugs can affect begonia plants. Use an insecticidal soap or narrow-range oil to control these pests. Always test a small portion of the plant for phytotoxicity from pesticide use to avoid foliar damage.