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Cross summer-blooming begonias with some of their cold-tolerant counterparts and you get the Rieger begonia—a great option for a pop of tropical color during the winter season. Pronounced “REE-ger,” the Rieger begonia is a winter flowering plant with blossoms like tea roses. Although these hybrids don’t have any scent, they more than make up for it with their riotously colorful, creamy blooms. Riegers range from reds, pinks, and bright yellows to shades of orange and stark white. What’s more, under the right conditions, they can bloom indoors for several weeks and they’re fairly easy to propagate, too.
Meet the Rieger begonia
Popularized by Otto Rieger of Nurtingen, Germany, the Rieger begonia initially dazzled judges at the International Flower Show in Vienna in1964. Rieger won the gold medal for his Rieger Elatior begonias—a cross between the standard wax begonia and the tuberous begonia.
With their vividly colorful flowers and large, glossy leaves, Rieger begonias (Begonia x hiemalis) quickly made their way to gardens and greenhouses across the U.S. and Canada. These days you can find them listed for sale under the name “Rieger,” “Elatior,” or as the Hiemalis begonia or winter begonia. (The Latin “hiemalis” translates to “winter.”)
The best light for a Rieger begonia
Photoperiod bloomers like the Rieger begonia need a minimum number of hours of light in order to bloom. Ideally, your plants should get 14 hours of bright, indirect light daily. If you’re growing a Rieger begonia in a greenhouse or as an indoor houseplant, it can handle some direct sunlight as long as the ambient temperature stays relatively cool.
Watering how-to
Overwatering the Rieger begonia is one common mistake new begonia grower make. To determine whether it’s time to water, feel the top inch or so of your plant’s soil. If it feels dry, water your plant by setting the base its pot in a shallow dish of water. Give the plant some time to draw water up from the bottom, but don’t let it remain this way for too long, as that can promote root rot. Ten minutes is ample.
Also, as a general rule, you should always try to keep the leaves of your Rieger begonias dry. This helps reduce the likelihood that your plant will contract a common fungal disease like powdery mildew.
Ideal temperatures for a Rieger begonia
Your Rieger begonia should thrive as long as you can provide it with a microclimate that is at least 50 degrees F (10 degrees C) at night and about 70 degrees F (21 degrees C) during the day. Plants will suffer in temperatures exceeding 80 degrees F (27 degrees F.)
Outdoor growing
If you live in USDA hardiness zones 9a to 11b, you may be able to keep your Rieger begonias growing outdoors, year-round. Just remember that these plants do best if grown near a wind break and if they’re planted in a spot that gets part sun in the early morning or evening rather than full sun during the hottest part of the day.
Caring for a Rieger begonia in winter
For Rieger begonias grown as indoor houseplants during the winter, it’s best to keep them away from drafts and watch your humidity levels. Indoor heating can dry out the air—and your plants. Boost humidity levels with a humidifier as needed. (Conversely, if overly high humidity becomes a problem, add extra space between plants and periodically stir the air with an oscillating fan.)
How to get a Rieger begonia to flower
As long as your Rieger begonia gets enough bright, indirect light—and provided its other needs are met—it should flower. Still, if you’ve moved from short days to a period of longer day length and you don’t see blooms, make sure that your plant isn’t in full shade. Move it to a sunnier window, but keep it out of direct light.
Have any new plants rooted from stem cuttings or started from leaf-tip cuttings? These may require three or four months to become established enough before they’ll begin flowering.
Once it does start flowering, pruning away old flowers will encourage more blooms.
Fertilization tips for the Rieger begonia
For bigger blooms, apply a liquid fertilizer like Fox Farm Tiger Bloom Liquid Concentrate. You can dilute this high-phosphorous fertilizer to accommodate your preferred feeding schedule. For instance, you might apply a mixture that’s half strength twice per month or switch to one-quarter strength for weekly feedings.
Also, for best results, your soil pH should be between 5.5 and 6.0. Not sure how acidic your mix is? Check it with a pH tester.
How and when to repot
Once you notice your begonia’s roots have begun to peek out of your pot’s drainage holes, it’s time to choose a slightly larger pot size and carefully repot your plant. Rieger begonias perform best in fast-draining soil. You can either use a specialty potting mix or make your own with equal parts peat moss (or a peat moss substitute) and sand or perlite.
Incidentally, Rieger begonias are often thought of as “disposable plants,” but it is possible to enjoy new blooms every year—and keep perfectly good plants out of the landfill! See, towards the end of the growing season, Rieger begonias stop flowering and go through a dormant period. At this point, you can either root new cuttings from your original plant or cut it back to about six inches tall and wait. After several weeks, you should see new shoots and new leaves emerging.
Additional care tips
Routinely examine plants for signs of insect infestation, and carefully check plants for pests before bringing them home from the greenhouse. While common pests like mealybugs and aphids leave telltale sap behind, spider mites are harder to spot. Look for their fine webbing or yellowing, stippled areas on foliage. You can knock back serious infestations of whiteflies and similar pests with insecticidal soap.
Flower power
If you want a splash of color to help get you through until spring, you can count on the Rieger begonia. Also known as the winter begonia or Elatior begonia, this wax-and-tuberous-begonia cross makes a great houseplant, producing vibrant flowers for a minimum of several weeks.
Remember to provide it with cool temperatures and bright, indirect light, feed regularly with a high-phosphorus, liquid fertilizer, and pinch spent blooms to keep the colors coming. You can even start new cuttings or allow your original plant a short period of dormancy in order to enjoy new sets of flowers year after year.
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Marlene Southard says
Thank you very much. I will try to multiply them and hope to be successful.