One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Houston you can determine when it's the best time to plant onions by looking at the USDA zone info.

Planting Calendar for Onions

Frost tolerance for onions:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Onions can survive in quite a bit of cold which means that you can plant them much earlier in the year than more sensitive plants.

The earliest that you can plant onions in Houston is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably October. If you wait any later than that and your onions may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your onions indoors.

Last Frost Date

On average all chance of frost has passed is on February 15 in Houston. You should expect an average low temperature of 20°F in the coldest months of winter.

Since the USDA zone info for Houston is not always accurate the actual date of last frost changes from year to year. Since half of the time in Houston you get a frost after February 15 be ready to cover your onions in the event of one of those late frosts.

USDA Zone Info for Houston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Houston

You may be interested in your other planting guides for Houston.