One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of making a decision about when to plant zinnia is to look at the USDA zone info for Hartford.

Planting Calendar for Zinnia

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

Zinnia are not cold tolerant which means that you must wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant zinnia in Hartford 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 fully mature. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Hartford and it can change quite a bit from year to year. Since half of the time in Hartford it frosts late in the year after April 15 be ready to cover your zinnia in the event of a surprise late frost.

USDA Zone Info for Hartford

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 Hartford

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