Articles and musings
BOB TANEM IN THE GARDEN
ALL ABOUT TUBEROUS BEGONIAS
Several years ago with one of my first broadcasts with Owen Spann on another
station a question came across the air about Tuberous begonias. The question was about when the tubers are ready to go into the ground. In the plant vernacular the term describing the growth buds on a tuber is “pink tits”. With 300,000 or more people
listening to the program I just couldn’t bring myself to saying “pink tit” on the radio.
This was almost 20 years ago and the term is probably acceptable now, but not then. I am not a quick thinker when the pressure of radio is upon me so the “pink tit” became pink “duby-dab.” Spann picked the term up and I became, not only America’s happy gardener, but good old Mister “Duby-dab.” It was quite some time before that moniker wore off.
My answer on the air was, “When the pink (tits) start to show, it is time to plant them.” What was true then is true now. I thought I would share with you some of the finer points of successful growing of Tuberous begonias. There just isn’t a more glorious flower to grow in the garden.
There are two varieties of Tuberous begonias, plus a new introduction on the market of Multiflora begonia. The care of all of them is the same. They thrive in morning sun or late afternoon sun (after 4 o’clock). If you live on the coast, they will grow in full sun. Many gardeners will put them in too much shade and will be disappointed because they will not bloom properly, nor will they be healthy. If you are starting out with new tubers you should select the largest tubers you can find. When you get them home place them on a flat that has some moisture. The sawdust that they are packed in should be discarded. They should not be kept wet, but the soil medium should be moist at all times. Once the “pink tits” start to show they are ready to plant.
Let’s describe the hanging varieties first because I have some helpful tips that will insure success. Perfect drainage is the key to success for hanging baskets of tuberous begonias. To insure perfect drainage I would purchase wire baskets, sometimes called moss baskets,
and fill them with green moss around the sides with planting mix in the center. I recommend planting mix because it doesn’t have any sand. Sand tends to hold moisture to the point of being saturated. This is not healthy for the tuber. The planting mix must be new with each planting. You can add your own compost to the soil if it is well composted. I also recommend a couple of cups of alfalfa pellets to the soil as a fertilizer base. Plant the tuber on the surface and do not cover the hollow spot where the “pink tits”are growing.As the first leaves start to form you can start feeding them. I recommend feeding with a liquid fertilizer (VF 11) once a week. Spray the foliage as well. Because of the perfect drainage you will probably have to water every other day. Do not water the plants after three o’clock, because you do not want them to go through the night with wet foliage.
Tubers in the ground are slightly more difficult to grow so I recommend that you grow them in two gallon containers using the above soil mix. You do not need to line the pot with green moss. Set the pot into a hole in the garden with drain rock on the bottom. This will insure the proper drainage. The plants will not require every other day watering because the surrounding area is more likely to be more moist than in a hanging basket. Here again, do not water in the late afternoon. The fertilizing program is the same.
Multiflora begonias are usually purchased in 6” pots in full bloom. The first year they will be quite content to stay in the pot. After that the care would be the same as upright Tuberous begonias. Here fertilizer is of the utmost importance. Mildew is one of their most common diseases. I have a favorite way of defeating mildew. I have a compost pile, actually a worm bin. I take a scoop of compost and put it into gallon of water and let it stand in the sun for a couple of days. You need to cover the container, otherwise the sun will kill the microbes that you are growing. Let this material settle and use it as a spray on the foliage when you first notice mildew. The microbes in the spray will neutralize the mildew and protect the plant. One other thought for the moss basket. Plant some Sweet Alyssum on the sides of the basket and you will have instant color.