What month do you plant watermelons? For most regions of the United States, the best planting time for watermelon crops is late spring or early summer. This means that May or June is usually the ideal month to plant your watermelons outdoors. For states with shorter growing seasons, such as those in the colder northern climates, the window of opportunity may be more limited and begin sometime around mid-May instead. No matter what region you’re in, it’s important to keep an eye on weather fore