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

The USDA zone info for Waterloo should be reviewed to figure out when it's the best time to plant tall phlox.

Planting Calendar for Tall Phlox

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

You can plant tall phlox a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant tall phlox 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 tall phlox and expect a good harvest is probably September. Any later than that and your tall phlox may not have a chance to really do well. You can get started a couple of weeks earlier by starting your tall phlox indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Waterloo. It might get as low as -20°F during the coldest months of winter.

Always keep in mind that USDA zone info for Waterloo is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Waterloo you get a frost after April 15 be ready to cover your tall phlox if you have a surprise 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.