One of the first steps you take when you are getting a good idea your gardening schedule is find your 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 London can be read to determine when to plant dahlia.

Planting Calendar for Dahlia

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

It's probably a bad idea to plant dahlia until after the last frost has passed because they require warm weather.

The earliest that you can plant dahlia in London 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. Any later than that and your dahlia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your dahlia indoors.

Last Frost Date

The average date of last frost is April 15 in London. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for London is an average the actual date of last frost is different every year. Since half of the time in London last frost occurs after April 15 be ready to protect your dahlia in the event of a surprise late frost.

USDA Zone Info for London

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in London

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