Select a Planting Date
To determine the best planting date to establish a healthy stand, use a 5-day forecast of accumulated degree-days (heat units) and on-site soil temperature readings. Good stand establishment requires sufficiently warm air (measured in heat units) and suitable field soil temperatures. Use the following guidelines for 5-day degree-day forecast plus field soil temperatures until an optimal planting date is determined.
Cotton planting 5-day degree-day forecast
March 10th is the first date available for planting in the San Joaquin Valley. It marks the end of the 90-day host-free period for the pink bollworm control program, but does not necessarily mark the ideal planting time. Optimal planting time depends on soil temperatures at planting and during the 5 days following planting. Cotton seed requires approximately 50 degree-days to accumulate in order to emerge when planted at an optimum planting depth. It is also important that temperatures be consistently warm and don’t drop during the first 5 days after planting. To determine the ideal window for planting, start taking soil temperature readings in your fields on March 5 th (see below) and follow forecasts from the Cotton Planting Forecast. Forecasts for the San Joaquin and Sacramento valleys are updated every day from early March through the end of April each year.
Use the following guidelines to interpret the 5-day forecast, also taking into account your field soil temperature readings:
Field soil temperature readings
Couple the 5-day forecast with soil temperature readings from a number of locations in your field. A soil temperature reading of 58° to 60° F, taken at 8 AM, is considered the minimum temperature required for good stand establishment, as long as the 5-day forecast predicts favorable conditions for the next 4 days.
To measure soil temperature:
Many factors influence soil temperature. These include wet versus dry soil, bed orientation, bed type (flat versus furrow), and residue cover in reduced-till areas. Therefore, measure within a representative area in which you will plant.
Check the crop after planting. If cotton emerges in:
Note that if you planted your cotton “deep” for adequate moisture, the degree-day accumulation will be affected and emergence will be later.