the show

Naturalizing Spring Bulbs

air date: September 17, 2011

Chris Wiesinger from The Southern Bulb Company selects drought-tough naturalizing spring bulbs. Find out more in his book, Heirloom Bulbs for Today, co-authored with Cherie Colburn. On tour, visit Lauren and Scott Ogden’s Austin garden. Daphne explains how to divide bearded iris to promote flowering. Trisha Shirey demonstrates row cover to shade in heat, protect in freeze, and fend off insects.


Question of the Week

Why don’t my bearded iris bloom? When should I divide them?

Lack of sun, nutrient deficiency, or rhizome rot could be the problem. But, most likely they are just too crowded. Dividing your bearded irises in September will improve their blooming next spring.

Dig them up with a spade or a shovel and cut off the mother rhizome, which will never bloom again. This will be the biggest one and most likely doesn’t look too good. With a knife, cut away the new side rhizomes with their leaves.

Discard any rhizomes that are mushy or have holes in them (a sign of borers).

Dig a hole and make a little mound. Spread the roots over the mound and cover with soil. You want to anchor the rhizome but you don’t want to completely cover its top. If you have several to do and it’s a hot day (or you need to keep them overnight), keep the roots moist with a damp newspaper or paper towel until you’re ready to replant.

If the iris doesn’t appear to be overgrown (you’ve divided with 3-4 years), but has yellow foliage, go ahead and fertilize with a high phosphorous fertilizer. Nitrogen-PHOSPHORUS-Potassium.

Nitrogen encourages green growth, so lowering the amount of nitrogen will encourage the plant to focus most of its energy on producing flowers instead of leaves.

One other possibility is that your iris may not be getting enough sun. If that’s the case, simply dig it up and move it to a sunnier spot.

Watch Trisha’s video on how to divide your bearded iris.

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Plant of the Week



Iris is a super tough, drought-tolerant genus of plants, with many species, that do fabulously well in Central Texas gardens. And they're virtually indestructible, making them the perfect plant for both beginning gardeners, who need some successes to boost their confidence, and more seasoned folks, who need at least one or two garden beds to be easy-care. Irises are available in almost every color in the rainbow, from vibrant, glaring purples and yellows to the most muted lavenders, creams, and blues. And with so many different sizes, colors and types to choose from, it will be very difficult not to end up planting more Iris than you had planned on. Bearded Irises are perhaps the most familiar to most people, but there are also German, Siberian, Japanese, and Louisiana Irises. Some grow best in full sun, while others need a bit of shade. And some Irises, such as Siberian and Louisiana, prefer boggy, soggy soil. So if you have heavy clay, these plants may be perfect for you. Although gorgeous, Iris blooms don't last long, but the foliage is beautiful too, providing a nice sculptural element to the landscape. Like roses, Irises are an old-fashioned plant. Growing from a large underground stem, Irises are very easy to divide and pass along. The non-boggy species require very little water to survive and thrive. Irises are perennial, so they'll go dormant in early winter. In winter, be sure to cut the leaves of your Iris completely to the ground, and clean away any garden debris in your iris beds. Slugs, snails, and a whole host of insect larvae will happily overwinter in leaf matter, just waiting to munch on all the stored carbohydrates in your lovely Iris rhizomes, before they have a chance to grow and sprout with warmer temperatures.