The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of making a decision about when it's the best time to plant coreopsis is to consult the USDA zone info for Lewiston.

Planting Calendar for Coreopsis

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

Coreopsis do well in some cold which tells us that you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant coreopsis in Lewiston 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 coreopsis and expect a good harvest is probably September. You probably don't want to wait any later than that or else your coreopsis may not have a chance to really do well. You can get started a little bit earlier by starting your coreopsis indoors.

Last Frost Date

On average the last frost is on April 15 in Lewiston. It might get as low as -15°F during the coldest months of winter.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Lewiston and it can change quite a bit from year to year. Half of the time in Lewiston it frosts late in the year after April 15 so just be sure to be ready to cover your coreopsis in the event of one of those late frosts.

USDA Zone Info for Lewiston

Here is the info for USDA Zone 5b.

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

Plants to Grow in Lewiston

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