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.

It's a good idea to determine when it's the best time to plant zinnia by reviewing the USDA zone info for Riverdale.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You really shouldn't plant zinnia until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant zinnia in Riverdale 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. If you are starting your zinnia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Riverdale the average date of last frost happens on March 15. You can expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for Riverdale is not always accurate the actual date of last frost changes from year to year. Since half of the time in Riverdale there is a last frost after March 15 be ready to cover your zinnia in the event of one of those late frosts.

USDA Zone Info for Riverdale

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Riverdale

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