One of the first steps you take when you are getting a good idea 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.

The USDA zone info for Johnston should be used to determine when it's a good idea to plant arabis.

Planting Calendar for Arabis

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

Arabis tend to make it in quite a bit of cold which means that you can plant them a lot earlier in the year than more sensitive plants.

The earliest that you can plant arabis in Johnston is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant arabis and expect a good harvest is probably September. You probably don't want to wait any later than that or else your arabis may not have a chance to grow to maturity. You can get started a little bit earlier by starting your arabis indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Johnston. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Johnston is an average the actual date of last frost will vary from year to year. Half of the time in Johnston you get surprised by a frost after April 15 so make sure that you are prepared to protect your arabis in the event of a late frost.

USDA Zone Info for Johnston

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Johnston

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