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 figuring out when it's a good idea to plant tithonia is to refer to the USDA zone info for Ottawa.

Planting Calendar for Tithonia

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

Since tithonia are not cold tolerant it is important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant tithonia in Ottawa 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 tithonia and expect a good harvest is probably August. If you wait any later than that and your tithonia may not have a chance to really do well. If you are starting your tithonia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Ottawa. In the coldest months of winter you can expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Ottawa may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Ottawa last frost occurs after April 15 so make sure that you are ready to protect your tithonia if you have a surprise late frost.

USDA Zone Info for Ottawa

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

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

Plants to Grow in Ottawa

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