The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to figure out when to plant rudbeckia by reviewing the USDA zone info for Knoxville.

Planting Calendar for Rudbeckia

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

Since rudbeckia are moderately cold tolerant you can plant them just a bit earlier in the year than other frost tender plants.

The earliest that you can plant rudbeckia in Knoxville 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 rudbeckia and expect a good harvest is probably September. If you wait any later than that and your rudbeckia may not have a chance to really do well. You can get started a few weeks earlier by starting your rudbeckia indoors.

Last Frost Date

The average date of last frost is April 15 in Knoxville. You should expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Knoxville and it is different every year. Half of the time in Knoxville you get a frost after April 15 so just be sure to be ready to cover your rudbeckia in the event of a surprise late frost.

USDA Zone Info for Knoxville

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 Knoxville

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