the show

Grow the Best Vegetable Garden Ever

encore date: March 23, 2013

original air date: January 26, 2013

Grow the best vegetables ever with start-up tips from horticulturist Greg Grant, author of Texas Fruit & Vegetable Gardening. On tour, new gardener Ellie Hanlon turned a field of weeds into her dream of flowers and food. Daphne explains why plants freeze. Her pick of the week is native heartleaf skullcap. Trisha shows how to make compost tea.


Episode Segments

On Tour

The Ellie Hanlon Vegetable Garden

Moving to Austin in the worst drought ever didn’t stop Ellie Hanlon from fulfilling her dream to grow her first vegetable garden. With ingenuity, she turned a field of weeds into a beautiful garden filled with organic vegetables and flowers all year round. Follow her garden diary, including tips on irrigation, on her blog, Mostly Weeds.


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Question of the Week

Why do some plants die in freezing weather?

There are actually a few ways that freeze damage occurs on plants, but most commonly it happens when the frozen water in the plant thaws out. One day the plant looks okay; the next day, it’s mush.

Jerry Parsons, one of my favorite retired Extension specialists always explained this question with the challenge of an experiment. Fill a glass half-full with water and put it in your freezer. Take it out the next day, once it’s thoroughly frozen, and immediately place it under a warm stream of tap water and watch what happens.

Okay, I bet you guessed this without doing it! The glass will shatter as soon as the ice starts to thaw and crack, exactly as thawing plant cells will do as soon as the temperatures warm up.

Some plants contain more water than others, especially in their leaves. A pine tree has very little water stored in its leaves, so pine trees don’t generally freeze.

But tropical plants are from climates where the humidity is high and rain is usually plentiful, so they have lots of water in their leaves, making them very susceptible to cold temperatures.

Many plants also retain high amounts of water in their fleshy stems, so those may freeze too. Some will just lose their leaves but return; others will not survive.

Plants have different strategies for dealing with cold. Some die completely, leaving the next generation to carry on through their seeds in favorable conditions (like Salvia coccinea, zinnia, cosmos, annual gomphrena). Other warm weather annuals that don’t re-seed will completely die and must be replaced.

Others only lose their tender leaves and perhaps any tender new stem-growth (like Gomphrena grapes, Mexican mint marigold).

Some die all the way back to the ground, but have hardy root systems, allowing them to emerge after the harsh cold weather has passed. These include lantana, woody shrubs like Hamelia patens, turk’s cap and many others.

Succulents may lose a few leaves or the entire plant, depending on the species and its cold hardiness. Bulbs like crinums will lose their leaves but return in spring.

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Plant of the Week

Heartleaf Skullcap

Heartleaf Skullcap

Scutellaria Ovata

This particular Scutellaria looks a lot like many of our blue-flowering Salvias. And there's a good reason for that: they're in the same plant family, the mint family. Even though heartleaf skullcap may look tender, it's actually a very cold tolerant native plant. This fuzzy gray groundcover emerges after hot weather to spread among dormant perennials or to join winter annuals, even in snow! Grow it in part sun to dappled light. It likes to be on the dry side, too, so don't overwater. In spring, Heartleaf skullcap sends out little purple flower spikes that attract beneficial pollinators and hummingbirds. But, the oil it its leaves confers some deer resistance. As soon as it gets hot, it will go underground. Depending on weather, it may be slow to return, but will always come back in cooler weather. Its fleshy roots will spread, so you can dig them up and move to new areas where you want to cover bare winter ground with fuzzy gray foliage.