Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 Oak Brook can be used to estimate when to plant lithospermum.

Planting Calendar for Lithospermum

Frost tolerance for lithospermum:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Lithospermum are not cold tolerant which tells us that you have to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant lithospermum in Oak Brook is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant lithospermum and expect a good harvest is probably August. If you wait any later than that and your lithospermum may not have a chance to fully mature. You can get started a little bit earlier by starting your lithospermum indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Oak Brook. In the coldest months of winter you can expect an average low temperature of -15°F.

Keep in mind that USDA zone info for Oak Brook is an average and the actual date of last frost is different every year. Since half of the time in Oak Brook you get a frost after April 15 be ready to protect your lithospermum if you have one of those late frosts.

USDA Zone Info for Oak Brook

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 Oak Brook

You may be interested in your other planting guides for Oak Brook.