Planting Date

Generally speaking, early June is the best time to plant dry beans. Planting should occur after the risk of spring frost has past and when there is not a risk of heavy rain after planting.

The ideal germination temperature for dry edible beans is 15°C or above. The table below displays the ideal planting dates according to geographic region. The highest yields are obtained by planting within these dates. A map displaying Corn Heat Units is provided in Figure 1. Check with the seed distributor for variety-specific planting recommendations.

Table 1. Planting date guidelines
CHU Geographic Area Planting Date Guidelines
Less than 3,000 CHUs May 26-June 6
3,000-3,200 CHUs May 30-June 10
More than 3,100 CHUs June 7-June 20

Dry edible beans are less vigorous than soybeans and must be planted when soil conditions are warm and moist, ensuring quick, uniform emergence. Low temperatures at planting (below 13°C) increase the risk of slow emergence, and damage from herbicide injury, soil crusting and root rot. Optimum plant growth occurs between 18°C–23°C. The minimum temperature for growth is 10°C and maximum temperature is 32°C.

When determining the planting date, temperatures at flowering must also be considered. Planting within the appropriate dates will avoid hot, dry weather during flowering and ensure a timely harvest. Temperatures greater than 32°C can cause “flower blasting” (dropping of buds and flowers). Regardless of planned planting date, it is most important that that the soil is fit and that heavy rain is not expected within a few days of planting as this can cause soil crusting. Under late planting conditions, carefully consider when dry edible beans will mature before continuing to plant. Dry edible beans are less able than soybeans to adapt to a shorter growing season from late planting.

Figure 1. Crop Heat Unit map of Ontario. This map is based on weather data from 1971–2000 with a common season start date across the province of May 1. Source: Weather Innovations Inc. (WIN)


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