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.

The first opportunity to plant onions in Johnston can be figured out by looking at the USDA zone info.

Planting Calendar for Onions

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

Since onions are very cold tolerant you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant onions 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 onions and expect a good harvest is probably September. Any later than that and your onions may not have a chance to really do well. You can get started a few weeks earlier by starting your onions indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Johnston. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Johnston may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Johnston you get a frost after April 15 be ready to protect your onions if you have 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.