One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's a good idea to determine when it's the best time to plant tropical hibiscus by checking out the USDA zone info for Johnston.

Planting Calendar for Tropical Hibiscus

Frost tolerance for tropical hibiscus:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

It's not a good idea to plant tropical hibiscus until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant tropical hibiscus 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 tropical hibiscus and expect a good harvest is probably August. Any later than that and your tropical hibiscus may not have a chance to grow to maturity. If you are starting your tropical hibiscus indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Johnston the average date of last frost happens on April 15. You can expect an average low temperature of -20°F in the coldest months of winter.

It's important to remember that USDA zone info for Johnston is just an average and the actual date of last frost is different every year. Since half of the time in Johnston it frosts late in the year after April 15 be ready to cover your tropical hibiscus 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.