The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Thornton can be reffered to in order to determine when to plant roses.

Planting Calendar for Roses

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

Since roses are one of those plants that can tolerate a little bit of cold weather you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant roses 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 roses and expect a good harvest is probably September. You probably don't want to wait any later than that or else your roses may not have a chance to really do well. You can get started a few weeks earlier by starting your roses indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Thornton. In the coldest months of winter you can expect an average low temperature of -15°F.

It's important to remember that the actual date of last frost may not be accurate from year to year 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 last frost occurs after April 15 so always be ready to protect your roses if you have a late frost.

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.