The plant’s unique and colorful appearance, including flowers that range from white to pink to coral, is what makes it so popular among plant enthusiasts. However, it is a temperate, tropical perennial native to Central America and can only survive outdoors in zone 10 or above, making it hard to keep it going outdoors anywhere in the USA. Growing it indoors does have some challenges, as it is rather fussy about its growing conditions. But people who love this unusual plant agree it is worth the effort.
Light
This begonia does best in partial sunlight. Indirect sunlight is best indoors, near a window. You may want to relocate it occasionally as the sunlight moves around according to the seasons, especially in winter as daylight hours grow shorter.
Soil
The polka dot begonia prefers a moist, rich soil. Since it is most often grown in containers or indoors, a good potting mix should suffice, or a sandy loam soil. Be sure there is adequate drainage; this can be improved by adding some perlite.
Water
It’s very important not to overwater your begonia. Let soil dry out to about a half inch on the surface before watering. Overwatering can cause root rot which can eventually kill the plant. Watering no more than twice a week should be sufficient but this varies depending on humidity levels in your home also; you can gauge the right amount by checking the soil before watering.
Temperature and Humidity
This plant is rather fussy about its ideal temperature. Being a tropical, its perfect growing conditions should emulate its native areas. Temperatures between 65 and 70 are best. Temperatures below 60 degrees Fahrenheit can cause the plant to wilt. Begonia maculata needs a steady level of humidity, but not too much (45 to 50%), so using a humidifier is advisable if your home tends to have dry air. Placing it in or near the bathroom or kitchen will help increase the humidity levels. Placing saucers of water near the plant can help keep humidity consistent also. However, too much humidity can cause problems such as mildew or fungal rot, so monitor your begonia for any issues.
Fertilizer
A fertilizer can be used to help liven up the blooms on your polka dot begonia. A basic slow-release liquid fertilizer in a 10-10-10 formula should work fine; use this in spring and apply once every 2 to 3 weeks to increase blooms as needed.
Propagating Begonia Maculata
You can propagate this plant with small cuttings. The best timing for propagation is when there are the fewest flowers on the plant, such as late winter.
How to Get Begonia Maculata to Bloom
Under good growing conditions, this plant normally blooms from April to July, and sometimes there is a second period of bloom in late winter (January or February). This plant can bloom up to three times per calendar year in optimal conditions. But if your plant isn’t blooming there are some things you can do to help it along. The most important factor is adequate light. Begonias are often thought of as shade plants, but Begonia maculata needs a good amount (at least 6 hours) of indirect sunlight to bloom. If your window doesn’t provide adequate light you can try augmenting this with a grow light, arranged to provide indirect light. It is also possible to over-fertilize your plant, which can prevent flower formation. One sign of over-fertilizing, particularly with nitrogen fertilizers, is vigorous growth of leaves and stems with no flower formation. Try cutting back on fertilizing and see if this helps. Overwatering can affect blooming also, and ultimately lead to root rot.
Pruning Begonia Maculata
Your polka dot begonia also needs regular pruning to keep it from getting too overgrown or leggy. The best time to do this is late autumn or after a period of bloom when the flowers are starting to drop off and fade. Use a sharp small pair of snips to make a clean cut.
Common Pests and Plant Diseases
This plant is somewhat susceptible to red spider mites, whiteflies and mealybugs. Fungal diseases and bacterial leaf rot can be a problem if there is overwatering or too much humidity.
