One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The best time to plant romaine lettuce in Sonora should be figured out by using the USDA zone info.

Planting Calendar for Romaine lettuce

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

Since romaine lettuce do well in cold you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant romaine lettuce in Sonora 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 romaine lettuce and expect a good harvest is probably October. Any later than that and your romaine lettuce may not have a chance to really do well. Starting your romaine lettuce indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is February 15 in Sonora. It might get as low as 20°F during the coldest months of winter.

Remember that USDA zone info for Sonora is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Sonora there is a last frost after February 15 so make sure that you are ready to cover your romaine lettuce in the event of a surprise late frost.

USDA Zone Info for Sonora

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 Sonora

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