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.

In Billings you can figure out when it's a good idea to plant romaine lettuce by looking at 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 do well in cold which tells us that you can start planting them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant romaine lettuce in Billings is March. However, you really should wait until April 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 August. You probably don't want to wait any later than that or else your romaine lettuce may not have a chance to fully mature. Starting your romaine lettuce indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Billings. You should expect an average low temperature of -25°F in the coldest months of winter.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Billings and it changes from year to year. Since half of the time in Billings it frosts late in the year after May 15 be ready to protect your romaine lettuce in the event of one of those late frosts.

USDA Zone Info for Billings

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°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 -20°F.

Plants to Grow in Billings

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