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.

By reviewing the USDA zone info for Zimmerman you should be able to figure out when it's a good idea to plant romaine lettuce.

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 can survive in pretty solid cold which means that you can plant them much earlier in the year than other plants that might not handle the cold.

The earliest that you can plant romaine lettuce in Zimmerman 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. If you wait 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 few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Zimmerman. You can expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Zimmerman is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Zimmerman last frost occurs after May 15 so make sure that you are prepared to protect your romaine lettuce in the event of a surprise late frost.

USDA Zone Info for Zimmerman

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

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

Plants to Grow in Zimmerman

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