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.

The earliest that you can plant black radish in Ottawa should be estimated by reviewing the USDA zone info.

Planting Calendar for Black radish

Frost tolerance for black radish:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Black radish do well in a little bit of cold which means that you can plant them a little bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant black radish in Ottawa is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant black radish and expect a good harvest is probably September. You probably don't want to wait any later than that or else your black radish may not have a chance to really do well. You can get started a couple of weeks earlier by starting your black radish indoors.

Last Frost Date

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

Since the USDA zone info for Ottawa is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Ottawa you get surprised by a frost after April 15 be ready to cover your black radish 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.