Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant mustard greens in Zone 4b should be figured out by using the USDA zone info.

Planting Calendar for Mustard greens

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

You can plant mustard greens just a bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant mustard greens in Zone 4b 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 mustard greens and expect a good harvest is probably August. You probably don't want to wait any later than that or else your mustard greens may not have a chance to really do well. Starting your mustard greens indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Zone 4b and it can change quite a bit from year to year. Half of the time in Zone 4b last frost occurs after May 15 so make sure that you are prepared to protect your mustard greens if you have one of those late frosts.

USDA Zone Info for Zone 4b

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 Zone 4b

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