Watermelon cultivation period

In northern China, year-round watermelon production still must take into account the market impact of transporting pumpkins northward; at present, Hainan Province exerts the greatest influence on the northern market. Hainan’s watermelon production is concentrated in two main seasons: one is autumn sowing with winter harvest, with peak market availability in January; the other is winter sowing with spring harvest, peaking in April.
Based on the foregoing, the following outlines the primary cropping sequences currently employed in watermelon production.
I. Open-field cultivation: cultivation period
1. Spring crop
For the late‑frost‑free planting season, seedlings transplanted from nurseries, seedling‑transplanted crops, and direct‑seeded crops are all feasible.
2. Summer crop
In the Huang-Huai-Hai region, sowing takes place from late May to early June, with harvest occurring in mid-to-late August.
3. Autumn Crop
In the Huanghuaihai region, seedlings are sown in early to mid-July, transplanted in mid- to late July, and harvested in mid- to late September. This crop of watermelons hits the market around National Day and the Mid-Autumn Festival, enjoying a favorable consumer demand. Moreover, when harvested at the optimal maturity stage, these watermelons can be stored and kept fresh until the end of the year.
II. Introduction to Protected Cultivation Timing
1. Early spring crop
These include cultivation methods such as small arch tunnels, plastic mulch combined with small arch tunnels, plastic mulch plus near‑ground cover, and windbreaks paired with small arch tunnels. Transplanting can be carried out 20–25 days earlier than in open fields; options include seedling transplantation, sprout transplantation, and direct seeding, though seedling transplantation makes the most effective use of protective facilities to achieve early maturity. For seedling transplantation, sowing can be done 30–35 days before transplanting—corresponding to 55–60 days prior to the local open‑field transplanting date—in sunny seedbeds or in large or small heated greenhouses.
2. Early Spring Cultivation
Spring early-season cultivation in plastic greenhouses and medium-sized sheds is currently a widely adopted cropping system. It features relatively simple equipment and straightforward production techniques. In particular, when the market begins to absorb large quantities of watermelons as local average daily temperatures rise above 20°C, it delivers highly favorable economic and social returns. In the Huang–Huai–Hai region, sowing and seedling raising typically occur around late January, with transplanting in early to mid-March, harvesting the first crop in early May, and the second crop in early June.
3. Autumn Delayed Cultivation
In the Huanghuaihai region, seedlings are typically sown around mid‑August and transplanted in late August or early September. Mulch should be applied before the daily average temperature drops below 18°C, with harvest occurring in the first or middle part of November. Other regions may follow these guidelines. For this crop, the sowing date must not be too late—particularly in the Huanghuaihai area, where prolonged cloudy and snowy weather in November can prevent proper maturation, leading to significant losses. By the time this batch of watermelons reaches the market, temperatures are already cold; if there is a supply of field‑grown autumn‑crop watermelons stored for later sale, the economic value of this production diminishes considerably. However, if there is a specific demand, such a planting can be considered, and storage‑based preservation can extend availability well into winter.
4. Winter–Spring Crop
The key is to ensure market supply after the spring weather begins to warm. Because market demand plays a crucial role, launching too early may not yield favorable returns and could even increase production challenges. In the Huang-Huai-Hai region, sowing and seedling raising typically occur in early January, with transplanting in mid-to-late February and market entry in early to mid-April. The second crop of melons generally reaches the market in early to mid-May, aligning closely with the first‑crop harvest from plastic‑covered large and medium greenhouses that begin production in spring. In the Northwest and Northeast regions, the sowing date can be adjusted accordingly to delay planting.
With advances in technology, watermelons can now be brought to market year-round; however, to ensure their flavor, it is essential to master the proper planting schedule and cultivation techniques.