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Tomato Superstars

encore date: August 30, 2016

original air date: July 23, 2016

Meet some tomatoes that perform like champs and are lip-smackin’ yummy with Bill Adams, former Texas A&M AgriLife Extension-Harris County-and author of The Texas Tomato Lover’s Handbook. On tour, Jay Carpenter feeds his family with water-saving innovative wicking beds. In our extreme heat, plants can get sunburned, too. Daphne explains what happened to a boxwood hedge. Plus, we follow up on Marissa Garrett’s question last summer about sun scald on her agaves. See how she fixed the problem this year. Trisha harvests wild purslane (Portulaca oleracea) for its nutritious benefits and explains how to grow you own.

Question of the Week

What caused brown spots on my boxwoods?

Thanks to landscape architect Tait Moring for this great question! The boxwoods in this hedge are exhibiting sporadic areas of yellowing/browning leaves throughout the hedge. The damage appears to start on the tips of the leaves in most places, then proceeds in from the leaf margin.

Tait also noted that this hedge gets a lot of reflected heat from a white stone patio, so actually, he already knew the answer himself!

And we can confirm his suspicions: these are classic symptoms of sun burn, and heat buildup in the leaves.

I have some ‘Baby Gem’ boxwoods myself. Two of my plants border a mostly shaded sidewalk and never have any issues, but one borders my driveway, which is in complete sun for the entire day, and has the same damage as shown here.

While you can’t do anything about the reflected heat, you can alleviate some of the heat buildup in the leaves by watering the plants more frequently during the summer. In order to take in water from their roots, plants must lose water from their leaves. This process also helps with heat buildup. Much like sweating helps to lower our temperature slightly when we get too hot, for plants, water loss has a cooling effect. And when it’s really hot, water loss occurs quickly, depleting the leaf’s supply faster than the roots can replenish it.

When the leaves can’t replenish the water that’s evaporating, they desiccate from the edges towards the center, much like the drying up of a lake. If it’s really hot where these plants are, you may not be able to completely eliminate the problem, but watering often, maybe even daily, during super-hot periods of time, will mitigate the damage.

And boxwoods are resilient, so as soon as temperatures cool down, the plant will begin to recover. Just shear off as much of the damage as possible at the end of summer, which will encourage healthy new growth to take its place.

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Plant of the Week

Agave Sun Scald Remedy

Agave Sun Scald Remedy

Our plant this week is actually a follow-up to Marissa Garrett’s question in 2015 about an Agave Americana with severely blotched leaves. We diagnosed sun scald, caused when our extended cloudy, unusually cool/wet spring turned into blasting sunlight almost overnight. After we suggested shading the plants if possible, Marissa draped them until the temperature was solidly back in the 80s and the weather was much more consistent. They recovered just fine! To avoid the same problem in 2016, she draped them when we hit consistent 90° days. The shade fabric is held in place by the plant’s spines. Marissa periodically adjusts it so that it doesn’t hinder the leaves. Viewer pictures this week: Universal City gardener Lisa Caldera is growing lots of delicious tomatoes that she got at the Sunshine Community Garden sale. She’s growing Cascada Lava, Cream Sausage, Buckbee's New Fifty, and Jaune Flammee. She also had some Cherokee Purples, but the birds wiped those out. In her not-quite 200 square foot garden, she also grows onions, squash, peppers, beans and eggplant. And a few years ago she picked up two rather ragged blackberry plants and two raspberry plants from the clearance shelf for a song…only five dollars each! She planted them in a little patch and forgot about them. But she still got enough blackberries to make six jars of blackberry basil jam. This year the blackberries and raspberries are so abundant that she’ll fill up the kitchen! Robin McGary is also busy harvesting tomatoes and squash in her garden. And Kathy Boyle attributes all the spring rain to the largest squash she’s ever grown!

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