One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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.

One way of making a decision about when it's the best time to plant tree onions is to check out the USDA zone info for Harlingen.

Planting Calendar for Tree onions

Frost tolerance for tree onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Tree onions tend to make it in mild cold which tells us that you can plant them slightly earlier in the year than other plants that might not handle the cold.

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

The last month that you can plant tree onions and expect a good harvest is probably September. You probably don't want to wait any later than that or else your tree onions may not have a chance to really do well. Starting your tree onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on February 15 in Harlingen. You should expect an average low temperature of 25°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Harlingen and it will vary from year to year. Since half of the time in Harlingen it frosts late in the year after February 15 be ready to cover your tree onions if you have one of those late frosts.

USDA Zone Info for Harlingen

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Harlingen

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