Stunning rex begonias can flourish in your Texas garden with proper love, care

Its name is “Rex” begonia, and as far as I’m concerned it’s the king of the Plant Kingdom when it comes to stunning foliage. I’ve been fascinated by this plant since I was probably 8 or 9 years old.

It was hard to find rex begonias back then. You saw them in magazines and gardening references. They were offered in seed catalogs, but the seeds were like dust and it was seemingly impossible to get them to germinate and grow into real plants.

It’s been a real joy to watch this stunning plant become one of America’s sweethearts — widely available online, and commonly sold in retail nurseries and flower shops. It’s like a young horticulturist’s dreams have come true.

What you need to know …

Begonia rex-cultorum. The Missouri Botanic Garden says this name is applied to a group of cultivated begonias stemming from the wild species Begonia rex somewhere along the line. The species is native to northeastern India, southern China and Vietnam.

Hybridizers have gone crazy with this wonderful plant. You can Google until your fingers are worn to nubs. You’ll find hundreds/probably thousands of cultivated varieties in the market.

Rex begonias’ leaves display an endless array of jewel-like tones including silver, pink, purple, red, rose and green, often streaked, swirled and spotted. Leaf sizes range from 3 or 4 inches to as large as a dinner plate. They are borne in clumps or on extremely shortened stems.

When I first bought my 30x60-foot greenhouse I filled half of it with small rex begonia transplants from an out-of-state specialist. I bought 300 varieties and I planted them into 1-gallon pots. Most of them loved that greenhouse, and I soon had to repot them into 3-gallon containers.

By the end of the first summer there were some that were fading due to the Texas heat, so my herd was thinning. Eventually I cut back to my favorite 30 or 40, and I grew those for many years.

From those years of experience, I can tell you not all rex begonias handle Texas equally well. Some are easier than others. And I don’t think there’s a lot of reason to send you out looking for specific variety names. There are just too many on the market, and growers are leaning toward their own proprietary types.

In general terms, however, I have always found that most rex begonias do best with bright indirect light while they’re outdoors — no direct Texas sunshine. I grow mine where I would grow ferns or hostas, except I keep them in pots so I can take them into the greenhouse or house over the winter.

I choose a loose, highly organic potting soil. In fact, I mix my own consisting of 50% sphagnum peat moss, 20% finely ground pine bark mulch and 15% each expanded shale and horticultural perlite. Because that mix has no nutrients at all, I use a diluted solution of a high-nitrogen, complete-and-balanced, water-soluble plant food each time that I water my plants.

Most begonias have showy flower clusters, but most rex begonias do not. Because of that I keep the flower stalks pinched off my plants so that all of their energy can be expended on producing more leaves. As old leaves become frayed I pinch or trim them off.

Rex begonias prefer a soil mix that stays moist at all times — not wet, but certainly never dry to the point of wilting. They use a great deal of moisture during the growing season.

If you’re growing rex begonias indoors, position them on the brightest windowsill available. Protect them from any freezing weather, and don’t let them touch really cold glass, either. Rotate the plants every few days to keep them symmetrical. If you transition them outdoors during the growing season, do so carefully. Don’t expose them suddenly to bright light. It could burn their tender leaves.

If you’re interested in propagating rex begonias, the easiest way is with leaf cuttings. Use a very sharp knife or single-edge razor blade to remove a healthy, full-sized leaf. Trim its petiole (“stem” of the leaf) to be only 1/2-inch long. I use sharp shears to trim the leaf around its edges to be about half as large as it was originally.

Fill each pot with a mix of equal amounts of sphagnum peat moss and perlite and soak it thoroughly. Use a pencil to create insertion holes, one hole per leaf. Stick the leaf into the potting soil so that the base of the blade is barely covered by the soil. Firm the soil around the base of the cutting. Insert another leaf or two if you wish, then water the potting soil thoroughly.

Place the pot in a bright spot that’s out of direct sunlight. Cover it with dry cleaner’s plastic to hold humidity around the leaves as they form roots. When they offer slight resistance when you pull gently, it’s time to pot them into 4-inch pots. New plants will develop from the base of each cutting.

Of course, you could also grow your rexes from seed, but take it from the 14-year-old Neil from many years ago: you don’t want to go there. The seeds are too small and the work is too tedious. Plus, they don’t “come true” from seed. Leaf cuttings are a lot easier.

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.

This story was originally published December 24, 2021 at 5:30 AM.