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

By referring to the USDA zone info for Greencastle you should be able to figure out when it's the best time to plant dahlia.

Planting Calendar for Dahlia

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

It's probably not a good idea to plant dahlia until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant dahlia in Greencastle 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 dahlia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your dahlia may not have a chance to grow to maturity. If you are starting your dahlia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Greencastle. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Greencastle may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Greencastle you get surprised by a frost after April 15 be ready to cover your dahlia in the event of a surprise late frost.

USDA Zone Info for Greencastle

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 Greencastle

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