One of the first steps you take when you are making a decision about 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 Boulder should be used to estimate when you can plant chrysanthemums.

Planting Calendar for Chrysanthemums

Frost tolerance for chrysanthemums:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant chrysanthemums slightly earlier in the year because they do ok in moderate cold.

The earliest that you can plant chrysanthemums in Boulder 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 chrysanthemums and expect a good harvest is probably August. If you wait any later than that and your chrysanthemums may not have a chance to really do well. If you are starting your chrysanthemums indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Boulder and it changes from year to year. Since half of the time in Boulder there is a last frost after April 15 be ready to cover your chrysanthemums in the event of a 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.