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.

The USDA zone info for Belfast can be used to figure out when it's a good idea to plant diascia.

Planting Calendar for Diascia

Frost tolerance for diascia:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Diascia do ok in some cold which tells us that you can plant them a little earlier in the year than other frost tender plants.

The earliest that you can plant diascia in Belfast 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 diascia and expect a good harvest is probably September. Any later than that and your diascia may not have a chance to really do well. You can get started a few weeks earlier by starting your diascia indoors.

Last Frost Date

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

Remember that USDA zone info for Belfast is just an average and the actual date of last frost is different every year. Half of the time in Belfast it frosts late in the year after April 15 so just be sure to be ready to protect your diascia in the event of one of those late frosts.

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.