Answer: Welcome to Houston! The USDA Hardiness Zone map puts Houston in Zone 9a, but communities just north of the city are in 8b. The line between them bisects Harris County.
Each hardiness zone predicts the average minimum low temperatures for a given area, based on historical data.
In Zone 9a, the lowest temperature expected annually is 20-25 degrees Fahrenheit. In Zone 8b, it's 15-20 degrees F. The average rainfall in Houston is about 50 inches.
The annual frost dates in Houston are debatable. Depending on the source, the last freeze date is mid-February to mid-March and the first freeze is due from mid-November to mid-December.
Sometimes, when we have hot, dry summer weather, plants go dormant just as they do in winter. Then, when temperatures drop slightly and rains come, they think it's spring. They burst into bloom. It's not unusual, for example, for pink magnolias, azaleas and other spring blooming plants to suddenly put on a few flowers. There's nothing you can do about it, so just enjoy.
If you're a composter, you will find that organic matter may break down more quickly here due to the warmer climate. And because we have such a long growing season, you'll find you have plenty of nitrogen (grass clippings) and, in the fall, carbon (leaves) to use.
We have thick, albeit rich, gumbo soil and heavy spring and fall rains. Most plants do better in beds raised one to two feet above ground level by the addition of leaves, pine needles and/or organically enriched topsoil.
Clay soil does absorb water, but slowly. During heavy fast rains, water hitting concrete and clay soils mostly runs off into sewers, taking with it chemicals detrimental to bayous and bays.
Houston's climate is classified as humid subtropical. Because of the humidity, sunlight strength isn't as strong as it is farther inland.
The following website contains information about plants that are especially suited to growing in Houston:
Watering is best done in the early morning. Try to keep water off the foliage of plants to help them avoid diseases.
Best wishes with your new garden!
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