Planting Tuberous Begonias: Which End Is Up?
Begonias were named the National Garden Bureau’s 2016 annual of the year. This family of heat-loving and mostly shade-loving plants, includes rex begonias, wax begonias, Begonia boliviensis (‘Bonfire’) and our favorite — tuberous begonias.
A single begonia plant can produce an astonishing number of flowers. With tuberous begonias, the key to getting a big plant with lots of blooms is getting an early start. It takes about 3 months for the tubers to wake up, leaf out and start flowering. So in most parts of the country, the tubers should be planted indoors during February and March.
As with other types of bulbs, a begonia tuber is filled with stored food energy that the young plant uses to fuel its growth.
The outside of a begonia tuber is brown and covered with dried root hairs. If you cut the tuber in half, you can see that the inside is dense (and pink!) and resembles the inside of a potato (though it’s NOT edible). Like a potato, the outside of the tuber is also covered with little growth points or “eyes”.
Begonia tubers have two sides: one is cupped (concave) and the other is domed (convex). The domed side of the tuber should rest on the soil surface, so it sits like a bowl (as shown above). As the tuber starts to grow, fine root hairs form on both the outside and inside of the bowl.
Most of the tuber’s eyes are located inside the cupped area where they are safe from harm. When these eyes sprout, they will grow up toward the light and develop into the plant’s stems, leaves and flowers.
There are quite a few different types of tuberous begonias. There are cascading ones like Pink Balcony (shown below) that are perfect for hanging baskets. Lightly fragrant Odorata White and Odorata Red also have a cascading habit.
There are also roseform, ruffled fimbriata and picotee tuberous begonias. You can see them all on our website: www.longfield-gardens.com. Tubers are usually available for planting from February through May.