One of the best tools that you have as gardeners to help us determine 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.

You should be able to estimate when it's a good idea to plant rosemary by reviewing the USDA zone info for Waterloo.

Planting Calendar for Rosemary

Frost tolerance for rosemary:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Rosemary do well in cold which tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant rosemary in Waterloo 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 rosemary and expect a good harvest is probably September. Any later than that and your rosemary may not have a chance to really do well. You can get started a little bit earlier by starting your rosemary indoors.

Last Frost Date

The average date of last frost is April 15 in Waterloo. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Waterloo may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Waterloo you get surprised by a frost after April 15 so always be ready to cover your rosemary in the event of a late frost.

USDA Zone Info for Waterloo

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 Waterloo

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