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 earliest that you can plant romaine lettuce in San Bernardino should be figured out by referring to 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.

Romaine lettuce are very cold tolerant which tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant romaine lettuce in San Bernardino 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. You probably don't want to wait any later than that or else your romaine lettuce may not have a chance to grow to maturity. You can get started a little bit earlier by starting your romaine lettuce indoors.

Last Frost Date

On average the last frost has passed is on February 15 in San Bernardino. It might get as low as 25°F during the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for San Bernardino and it is different every year. Since half of the time in San Bernardino it frosts late in the year after February 15 be ready to protect your romaine lettuce if you have a late frost.

USDA Zone Info for San Bernardino

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 San Bernardino

You may be interested in your other planting guides for San Bernardino.