The USDA Zone info is a great tool for gardeners to help us figure out 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.

It's possible to figure out when it's a good idea to plant rhubarb by using the USDA zone info for Zone 4a.

Planting Calendar for Rhubarb

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

You can plant rhubarb a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant rhubarb in Zone 4a is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant rhubarb and expect a good harvest is probably August. If you wait any later than that and your rhubarb may not have a chance to fully mature. If you are starting your rhubarb indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4a. In the coldest months of winter you should expect an average low temperature of -30°F.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 4a and it will vary from year to year. Since half of the time in Zone 4a last frost occurs after May 15 be ready to cover your rhubarb if you have a surprise late frost.

USDA Zone Info for Zone 4a

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 Zone 4a

You may be interested in your other planting guides for Zone 4a.