One of the first steps you take when you are getting a good idea 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.

The USDA zone info for Denver can be looked at to determine when to plant lettuce.

Planting Calendar for Lettuce

Frost tolerance for lettuce:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Lettuce do well in moderate cold which tells us that you can plant them earlier than other frost tender plants.

The earliest that you can plant lettuce in Denver 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 lettuce and expect a good harvest is probably September. You probably don't want to wait any later than that or else your lettuce may not have a chance to really do well. If you are starting your lettuce indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Denver is just an average the actual date of last frost is different every year. Since half of the time in Denver it frosts late in the year after April 15 be ready to protect your lettuce in the event of one of those late frosts.

USDA Zone Info for Denver

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Denver

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