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.

A common way of estimating when it's the best time to plant calibrachoa is to refer to the USDA zone info for Belfast.

Planting Calendar for Calibrachoa

Frost tolerance for calibrachoa:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since calibrachoa do ok in moderate cold you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant calibrachoa in Belfast is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant calibrachoa and expect a good harvest is probably August. Any later than that and your calibrachoa may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your calibrachoa indoors.

Last Frost Date

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

Keep in mind that USDA zone info for Belfast is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Belfast there is a last frost after April 15 be ready to protect your calibrachoa if you have a surprise late frost.

USDA Zone Info for Belfast

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 Belfast

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