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.

The earliest that you can plant campanula in Riverside should be estimated by using the USDA zone info.

Planting Calendar for Campanula

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

You can plant campanula a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant campanula in Riverside 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 campanula and expect a good harvest is probably September. If you wait any later than that and your campanula may not have a chance to grow to maturity. Starting your campanula indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Riverside. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Riverside is not always accurate the actual date of last frost will vary from year to year. Half of the time in Riverside you get surprised by a frost after April 15 so always be ready to protect your campanula in the event of a surprise late frost.

USDA Zone Info for Riverside

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 Riverside

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