One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By checking out the USDA zone info for Flagstaff you should be able to determine when you can plant dahlias.

Planting Calendar for Dahlias

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

Dahlias require warm weather which tells us that it is necessary to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant dahlias in Flagstaff 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 dahlias and expect a good harvest is probably August. Any later than that and your dahlias may not have a chance to fully mature. You can get started a little bit earlier by starting your dahlias indoors.

Last Frost Date

The average date of last frost is April 15 in Flagstaff. You can expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Flagstaff may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Flagstaff you get surprised by a frost after April 15 be ready to cover your dahlias in the event of one of those late frosts.

USDA Zone Info for Flagstaff

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Flagstaff

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