It really is possible to grow juicy delicious watermelons in Atlantic Canada! Although this sweet fruit is over 90% water, it is a good source of Vitamins A, B6 and C, as well as potassium and the antioxidant lycopene. Growing Tips: Sow seed indoors 3 to 4 weeks prior to the last spring frost. This heat-loving crop thrives in a warm sunny location with rich organic soil. So amend your garden well. Black mulch may be used to conserve moisture and increase soil temperature.