One of the first steps you take when you are figuring out 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 first chance to plant zinnia in Johnston can be determined by referring to the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since zinnia do not do well in cold weather you must wait until after the last frost before you can plant them.

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

The last month that you can plant zinnia and expect a good harvest is probably August. If you wait any later than that and your zinnia may not have a chance to grow to maturity. Starting your zinnia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Johnston. You should expect an average low temperature of -20°F in the coldest months of winter.

Remember that USDA zone info for Johnston may not be accurate from year to year and the actual date of last frost is different every year. Since half of the time in Johnston last frost occurs after April 15 be ready to protect your zinnia 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.