The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant chrysocephalum in Boulder can be determined by looking at the USDA zone info.

Planting Calendar for Chrysocephalum

Frost tolerance for chrysocephalum:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since chrysocephalum require warm weather it's important to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant chrysocephalum 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 chrysocephalum and expect a good harvest is probably August. Any later than that and your chrysocephalum may not have a chance to grow to maturity. Starting your chrysocephalum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Boulder the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Remember that USDA zone info for Boulder is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Boulder last frost occurs after April 15 so just be sure to be ready to protect your chrysocephalum if you have 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.