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

One way of determining when it's a good idea to plant rudbeckia is to consult the USDA zone info for Alton.

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 a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant rudbeckia in Alton 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. Starting your rudbeckia indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Alton. You can expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Alton is an average the actual date of last frost changes from year to year. Since half of the time in Alton it frosts late in the year after April 15 be ready to cover your rudbeckia in the event of one of those late frosts.

USDA Zone Info for Alton

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Alton

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