One of the best tools that you have as gardeners to help us estimate 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.

In La Grande you can estimate when it's the best time to plant periwinkles by using the USDA zone info.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Periwinkles do not do well in cold weather which tells us that you really should 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 La Grande 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. If you are starting your periwinkles indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in La Grande. In the coldest months of winter you can expect an average low temperature of -5°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for La Grande and it is different every year. Half of the time in La Grande it frosts late in the year after April 15 so make sure that you are ready to cover your periwinkles if you have a surprise late frost.

USDA Zone Info for La Grande

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°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 0°F.

Plants to Grow in La Grande

You may be interested in your other planting guides for La Grande.