What does the agricultural proverb "plant melons and beans before and after Qingming Festival" mean?

This is an agricultural proverb, which means that the time to plant melons and beans is around Qingming.

During the twenty-four solar terms in Tomb-Sweeping Day, Tomb-Sweeping Day began to breathe when the sun moved to longitude 15 degrees. At this time, the temperature is getting warmer, the plants are sprouting, the weather is sunny, everything is thriving, and the Qingming is bright and clean.

With the arrival of Tomb-Sweeping Day gas, the atmospheric circulation in East Asia turns from winter to spring. The ridge line in the westerly belt moves frequently, and the low-level high and low pressure appear alternately. The temperature in the Jianghuai area changes greatly, and unstable precipitation such as thunderstorms gradually increases.

"Before and after Tomb-Sweeping Day, we planted melons and beans." During the period of Tomb-Sweeping Day, the average daily temperature in most parts of the country has risen to above 12℃ except the northeast and northwest regions, and there is a busy scene of spring ploughing everywhere from the north and south of the Yangtze River to the inside and outside of the Great Wall. "During my stay in Tomb-Sweeping Day, wheat grew in three stages." Wheat in the southern part of Huanghuai is about to start heading, rape has blossomed, and wheat in the northeast and northwest regions has also entered the jointing stage. In the later stage, we should pay close attention to fertilizer and water management and pest control. Dry farming in the north, early and middle rice in the south of the Yangtze River is suitable for sowing in large quantities, so we should seize the opportunity to sow early. "Pear blossoms", at this time, attention should be paid to artificial pollination to improve the fruit setting rate. Early rice planting in South China should be cleaned up and fertilized in time. Corn, sorghum and cotton will also be planted everywhere. The famous tea producing areas of "Before Tomorrow's Tea" are mined one after another, so it is necessary to collect them strictly and scientifically to ensure the yield and quality. At this time, the cold air in the north still has a certain influence and the weather is changeable. Attention should be paid to prevent the harm of low temperature and late frost weather to spring sowing crops such as wheat, rice seedlings and flowering fruit trees.