One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Del Rio can be used to determine when you can plant onions.

Planting Calendar for Onions

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

Onions are very cold tolerant which means that you can start planting them much earlier than other frost tender plants.

The earliest that you can plant onions in Del Rio 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. If you are starting your onions indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is February 15 in Del Rio. You should expect an average low temperature of 20°F in the coldest months of winter.

Since the USDA zone info for Del Rio is not always accurate the actual date of last frost changes from year to year. Half of the time in Del Rio you get a frost after February 15 so just be sure to be ready to cover your onions if you have one of those late frosts.

USDA Zone Info for Del Rio

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 Del Rio

You may be interested in your other planting guides for Del Rio.