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.

It's possible to determine when you can plant fennel by referring to the USDA zone info for Denver.

Planting Calendar for Fennel

Frost tolerance for fennel:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Fennel are very cold tolerant which means that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant fennel 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 fennel and expect a good harvest is probably September. Any later than that and your fennel may not have a chance to grow to maturity. If you are starting your fennel indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Denver is an average the actual date of last frost changes from year to year. Since half of the time in Denver you get a frost after April 15 be ready to protect your fennel in the event of a late frost.

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.