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

One way of estimating when it's the best time to plant lobelia is to check out the USDA zone info for Dubuque.

Planting Calendar for Lobelia

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

Lobelia are very cold tolerant which tells us that you can plant them a quite a bit earlier than other plants that might not handle the cold.

The earliest that you can plant lobelia in Dubuque 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 lobelia and expect a good harvest is probably September. Any later than that and your lobelia may not have a chance to fully mature. If you are starting your lobelia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Dubuque. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Dubuque is just an average the actual date of last frost is different every year. Half of the time in Dubuque you get a frost after April 15 so make sure that you are prepared to protect your lobelia in the event of a surprise late frost.

USDA Zone Info for Dubuque

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 Dubuque

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