The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Elk River it's a good idea to determine when you can plant napa valley fern.

Planting Calendar for Napa Valley Fern

Frost tolerance for napa valley fern:	Not tolerant of frost.
When to plant:	After the last frost.

Napa Valley Fern require warm weather which tells us that you need to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant napa valley fern in Elk River is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant napa valley fern and expect a good harvest is probably August. Any later than that and your napa valley fern may not have a chance to really do well. If you are starting your napa valley fern indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Elk River. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Elk River may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Elk River there is a last frost after May 15 be ready to protect your napa valley fern in the event of one of those late frosts.

USDA Zone Info for Elk River

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°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 -20°F.

Plants to Grow in Elk River

You may be interested in your other planting guides for Elk River.