One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. 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 Duluth you should be able to determine when it's the best time to 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 when the weather gets warmer.

Since napa valley fern are not cold tolerant it is necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant napa valley fern in Duluth 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. You probably don't want to wait any later than that or else your napa valley fern may not have a chance to grow to maturity. If you are starting your napa valley fern indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Duluth the average date of last frost happens on May 15. In the coldest months of winter you should expect an average low temperature of -30°F.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Duluth and it changes from year to year. Half of the time in Duluth you get a frost after May 15 so make sure that you are ready to protect your napa valley fern in the event of one of those late frosts.

USDA Zone Info for Duluth

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Duluth

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