One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Thornton you can figure out when it's the best time to plant celeriac by referring to the USDA zone info.

Planting Calendar for Celeriac

Frost tolerance for celeriac:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Celeriac do well in moderate cold which tells us that you can get them planted earlier than more sensitive plants.

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

Last Frost Date

The average date of last frost is April 15 in Thornton. It might get as low as -15°F during the coldest months of winter.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Thornton and it will vary from year to year. Half of the time in Thornton it frosts late in the year after April 15 so be sure to be ready to cover your celeriac if you have one of those late frosts.

USDA Zone Info for Thornton

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 Thornton

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