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 USDA zone info for Ottawa can be used to determine when you can plant iresene.

Planting Calendar for Iresene

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

Since iresene are not cold tolerant it is important to wait until after the last frost has passed before you can plant them.

The earliest that you can plant iresene 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 iresene and expect a good harvest is probably August. Any later than that and your iresene may not have a chance to grow to maturity. Starting your iresene indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Remember that USDA zone info for Ottawa is an average and the actual date of last frost changes from year to year. Half of the time in Ottawa you get surprised by a frost after April 15 so make sure that you are ready to cover your iresene in the event of 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.