One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Zone 4b you can estimate when to plant aubretia by looking at the USDA zone info.

Planting Calendar for Aubretia

Frost tolerance for aubretia:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant aubretia earlier in the year because they are very cold tolerant.

The earliest that you can plant aubretia 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 aubretia and expect a good harvest is probably August. Any later than that and your aubretia may not have a chance to fully mature. Starting your aubretia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Keep in mind that USDA zone info for Zone 4b may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Zone 4b it frosts late in the year after May 15 so be sure to be ready to protect your aubretia if you have a surprise late frost.

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.