The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of determining when you can plant violas is to consult the USDA zone info for Oroville.

Planting Calendar for Violas

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

Violas do ok in pretty solid cold which means that you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant violas in Oroville is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant violas and expect a good harvest is probably October. If you wait any later than that and your violas may not have a chance to grow to maturity. Starting your violas indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Oroville the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Since the USDA zone info for Oroville is just an average the actual date of last frost is different every year. Since half of the time in Oroville you get surprised by a frost after February 15 be ready to cover your violas in the event of one of those late frosts.

USDA Zone Info for Oroville

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Oroville

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