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 first chance to plant periwinkles in Forest Grove should be figured out 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 has passed.

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

The earliest that you can plant periwinkles in Forest Grove 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 little bit earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Forest Grove. In the coldest months of winter you should expect an average low temperature of 15°F.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Forest Grove and it changes from year to year. Half of the time in Forest Grove there is a last frost after March 15 so make sure that you are prepared to protect your periwinkles in the event of a late frost.

USDA Zone Info for Forest Grove

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Forest Grove

You may be interested in your other planting guides for Forest Grove.