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.

The USDA zone info for Denver can be used to figure out when it's possible to plant violas.

Planting Calendar for Violas

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

You can plant violas quite a bit earlier in the year because they are very cold tolerant.

The earliest that you can plant violas 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 violas and expect a good harvest is probably September. Any later than that and your violas may not have a chance to really do well. Starting your violas indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Denver. In the coldest months of winter you should expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Denver may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Denver it frosts late in the year after April 15 be ready to cover your violas 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.