One of the first steps you take when you are estimating 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.

In Sulphur you can estimate when it's a good idea to plant tree onions by looking at the USDA zone info.

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.

Since tree onions are barely cold tolerant 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 Sulphur 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 grow to maturity. Starting your tree onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is February 15 in Sulphur. In the coldest months of winter you can expect an average low temperature of 20°F.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Sulphur and it can change quite a bit from year to year. Since half of the time in Sulphur there is a last frost after February 15 be ready to protect your tree onions in the event of a surprise late frost.

USDA Zone Info for Sulphur

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 Sulphur

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