Choosing and Growing Tuberous Begonias

By Chuck DeLaney

Myth, fables, and children's tales often turn on a mystery figure that appears only occasionally. Rub the dirty old lamp and presto - the genie is at your command! Be it Aladdin's Lamp, or the Genie in the Bottle, isn't it great to have something marvelous appear from nothing?

This potential to produce a miraculous result from a humble origin is one of the wonders of childhood, and alas, as with many fascinations of childhood, the real world intervenes as we grow older. But there remain a few things in the less miraculous adult world that can still allow us to wonder at the beauty and power unleashed from a humble container.

For me, the tuberous begonia is one of those wondrous little things. If you like the idea of seeing miraculous blooms in vivid colors appear before your very eyes after growing out of a humble tuber that looks like a shriveled, shrunken dirty potato, then consider the tuberous begonia. After planting these expensive little tubers in about a half-inch or so of potting soil, new green growth appears in a short while. Slowly a rich and robust set of stems and leaves emerge. The exotic swirls and designs of the richly colored leaves disguise for a time the tight buds of the emerging flowers. From a tight, nearly bean-shaped initial bud will emerge a stunning blossom of surprising size and complexity.

In full glory, a tuberous begonia will be about a foot or so high and its leaves and stems may extend a foot in all directions. Every stem is rich with blossoms. As with all beauty that's breathtaking, begonias are fragile creatures and it's not uncommon for the stems to become so heavy with their dazzling blossoms that the flowers break off or the stems fracture. Also, as you might expect, these aren't plants for the strong sun and high heat of the Deep South or the Southwest. I put some pots out in the garden in a sheltered spot where the wind won't ruffle any leaves, and keep others indoors in an east-facing window so they get a few hours of sun a day.

To flourish, begonias need to be fussed over a bit. But then, all genies are generally high maintenance creatures. One supplier makes stakes that can be used to support stems that are laden with blooms, but I prefer to fashion my own from small sections of tree branches. To grow to maximum display, they need a fairly strong diet of fertilizer while the new growth is establishing itself, and I pot them in a mix of 1/3 potting soil, 1/3 peat and 1/3 sterile sand to promote good drainage. Begonias don't like to have wet feet, and the last thing you want to happen is have rot affect the tuber.

 

After a season of vivid display, usually running from June or July through September, all the blossoms and stems die back and you're left with just a humble tuber that can be stored for the winter and reinvigorated the following spring. Tubers from the source generally considered to produce the finest strains of Begonias, the British firm Blackmore and Langdon, can sell in the neighborhood of $40 to $50 for a single tuber. That's certainly a lot of money for a little thing, but I have several B & L tubers in my collection that have been performing steadily for close to ten years now. When you consider that a dozen tulip blossoms at a New York deli generally run $6, an investment in a begonia that will provide hundreds of blooms over its lifespan doesn't seem so extravagant. There are also lots of suppliers of great tuberous begonias that start at much lower prices. You may not find the same long period of bloom, and you might not find such a wide range of color, but it certainly might make sense to start with some less expensive kin and decide if you like the experience.

Most strains of tuberous begonias are of the standing variety, but I have grown varieties that work well in hanging baskets. There is at least one cultivator who has come up with a scented variety, but I've never tried them. With colors so intense, I think a scent would be overkill. But then, I don't like Genies with lots of perfume or aftershave either.

Growing Tips

In most locations these are plants that you'll start indoors in small clay pots and move to larger 10" diameter pots after the new growth has appeared. In both size pots I use the same soil, sand, peat mix vermiculite, but I find sand seems to keep my begonias happier. After the stems and blooms slow down and begin to die back, I drastically decrease watering.

Admittedly, at this point the genie doesn't look so good, so I put my pots in a corner that's out of sight. You might be tempted to trim the deflated stems, but this you cannot do. To allow the tuber to reset for the next growing season you need to let them die back naturally. After all the stems have broken off the tuber, you can either simply leave the tuber in the pot to let it dry out, or take it out of the pot and bury it in dry peat moss to over winter. Don't let the mice get at your tubers or they'll have a very expensive meal and you'll have to start all over next spring with a new purchase.

If you type "tuberous begonias" into your favorite search engine you'll be able to find lots of suppliers, information on growing, and probably if you look hard enough, a support group for people who love begonias too much. Enjoy!

Reprinted with permission from the Sheffield School of Design.