The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. 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 Boulder can be reviewed to estimate when to plant flowering maple.

Planting Calendar for Flowering Maple

Frost tolerance for flowering maple:	Not tolerant of frost.
When to plant:	After the last frost.

Flowering Maple are not cold tolerant which means that it's important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant flowering maple in Boulder is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant flowering maple and expect a good harvest is probably August. If you wait any later than that and your flowering maple may not have a chance to really do well. If you are starting your flowering maple indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Boulder. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Boulder is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Boulder there is a last frost after April 15 be ready to protect your flowering maple if you have a surprise late frost.

USDA Zone Info for Boulder

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 Boulder

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