Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can determine when to plant periwinkles in Roma by referring to the USDA zone info.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Periwinkles require warm weather which means that it is important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant periwinkles in Roma is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant periwinkles and expect a good harvest is probably September. You probably don't want to wait any later than that or else your periwinkles may not have a chance to fully mature. You can get started a few weeks earlier by starting your periwinkles indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Roma. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Roma is just an average the actual date of last frost will vary from year to year. Half of the time in Roma you get surprised by a frost after February 15 so always be ready to cover your periwinkles in the event of a surprise late frost.

USDA Zone Info for Roma

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 Roma

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