Ontario · Growing Zone 6a
Gardeners in London, ON can expect the average last spring frost around April 28, and the first fall frost around October 27, based on historical Environment Canada frost data for the area. That gives London a frost-free growing season of roughly 182 days. Actual frost dates shift by a week or two year to year, so use this as a planning baseline rather than an exact guarantee, and always check your local forecast before moving tender plants outside.
Most warm-season crops (tomatoes, peppers, squash) need transplanting only after the last frost has passed, and are usually started indoors 6 to 8 weeks before that date. Cold-hardy crops (peas, lettuce, spinach) can often go in the ground a few weeks before the last frost. As London's first fall frost approaches in October, it's time to plan the last harvests for anything frost-sensitive still in the ground.
GrowBlock builds your whole season timeline around dates like these automatically, indoor seed starting, transplant windows, and harvest, tuned to London specifically.
Plan your London gardenAround April 28 on average, though it can vary by a week or two either way depending on the year.
London is in zone 6a, with a frost-free season of about 182 days.