Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of figuring out when you can plant periwinkles is to check out the USDA zone info for Hillsborough.

Planting Calendar for Periwinkles

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

Since periwinkles do not do well in cold weather it is important to wait until after the last frost has passed before you can plant them.

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

The last month that you can plant periwinkles and expect a good harvest is probably August. Any later than that and your periwinkles may not have a chance to fully mature. Starting your periwinkles indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Hillsborough the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of 5°F.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Hillsborough and it is different every year. Half of the time in Hillsborough you get surprised by a frost after April 15 so be sure to be ready to protect your periwinkles in the event of one of those late frosts.

USDA Zone Info for Hillsborough

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Hillsborough

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