One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can determine when it's the best time to plant skullcap in Waterloo by referring to the USDA zone info.

Planting Calendar for Skullcap

Frost tolerance for skullcap:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Skullcap require warm weather which tells us that you have to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant skullcap in Waterloo 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 skullcap and expect a good harvest is probably August. Any later than that and your skullcap may not have a chance to fully mature. If you are starting your skullcap indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Waterloo and it can change quite a bit from year to year. Since half of the time in Waterloo it frosts late in the year after April 15 be ready to protect your skullcap if you have a 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.