General Care for Hiemalis (Rieger) Begonias
Hiemalis Begonias have long been used as an indoor flowering potted plant. This continues to be its main use because of the potential for it to last longer than the other indoor flowering pot plants such as Chrysanthemums, Kalanchoes, and pot roses. More and more growers are now starting to offer Hiemalis Begonias as an outdoor premium annual. They have smaller blossoms but much more color than non-stop begonias and bigger more elegant blossoms than regular fibrous varieties. ‘Dana’ and other ‘Barkos’ varieties tend to outperform other begonias in low light areas that are typically too dark for Begonias.
When to Plant
Like other Begonias, plant outside after the last frost. For most of the Puget Sound Area May 1st is a safe date.
Where to Plant
Begonias prefer a spot with bright indirect light. They can only take full sun at cooler temperatures. Often this means morning sun is ok but afternoon sun will burn.
How to Plant
Begonias have a tender root system, so when transplanting carefully remove it from the pot so as not to damage the root system. Make a hole big enough for the root ball, put the plant in and lightly fill around it with soil. Don’t pack the soil down just use water to settle the soil around the root ball.
Hiemalis Begonias are just as hardy as other Begonias typically used outdoors. They will last outside until the 1 st hard frost.
Hiemalis Begonias use much less water than most other plants and should only be watered half as often as other plants, in separate pots, around them. Water them thoroughly when the surface of the soil starts to dry out, but don’t leave them sitting in water for more than a few minutes.
Use a balanced fertilizer. Begonias are light feeders using about the same levels as most house plants and half as much as most bedding plants. Follow the directions on your fertilizer for plants that need light fertilizing.
Insects and Diseases
Aphids are the main insect threat to watch for. Outdoors Aphids usually prefer other plants. Powdery mildew is most likely to attack begonias in the spring and fall when night temperatures are low. Remove infected foliage and spray with an appropriate fungicide. Botrytis stem rot usually attacks begonias only after 1 st being hurt by transplant damage, over-watering, or from growing in a place without enough light. Most often it’s a combination of these problems that leads to Botrytis. Clean away any diseased plant parts and try to avoid the poor growing conditions mentioned.