Climatic requirements for green peas
Green peas are grown mostly by large scale contract farmers that sell the product to processors. The green pea Pisum sativum is a very well known and economically important vegetable crop in South Africa. The total area under production is about 10,000 ha. Most of the area is produced for freezing or canning only and a very small percentage is sold on fresh markets.
Production for processing is associated with large areas, mechanization, coordination of planting and harvesting to ensure a steady flow of peas to the factory without deterioration of quality in the field. Farming with processed foods require close cooperation between the farming activities such as spraying and harvesting and the processing factory.
There is a big difference between farming for the fresh markets and for the processing markets. Markets for fresh peas is very small. Prices fluctuate considerably on the fresh markets while factories pay a flat negotiated fee.
Green peas are mostly grown in humid areas such as Groblersdal, Mossel Bay, Gamtoos River Valley of the Eastern Cape. In the highveld areas like Witbank, Middelburg, Bethal, Standarton are also good for planting. Peas are highly perishable and the market or factory must be close by. Processing must take place within a hour after harvesting. That is one of the reasons why processing is prefered over fresh marketing. The second reason why fresh peas are not that popular is the amount of labour required to remove the pods from the pea without damage.
Peas need cool climates to grow properly. They are very sensitive to high temperatures. Ideally the temperature should be between 16-19°C. Maximum temperatures of 24°C are tolerated but as soon as it goes higher for long periods in the day the quality and quantity of the harvest decreases.
Peas can tolerate frost down to -2°C early on. As soon as the flowers start to form frost will damage the growth points and flowers.
Seed germinate between 5-29°C with the ideal temperature 23°C. There are so many varieties available on the market that there will be a pea cultivar that suits your climate.
day length is not an important factor as most peas are day length neutral. However, long day varieties, those that flower very late under short day conditions are often used.
Cool temperatures after germination promotes haulm development and vegetative growth. Frots during 50-65 days after planting is ok and will not harm the plant significantly. Be careful of frost 30-50 days after flowering as it may reduce yields significantly. The plant is now more adapted to higher temperatures during fruit set. Higher temperatures (23-28°C) will speed up growth and ripening. High rainfall and humidity increases the risk of leaf diseases which can reduce yields, increased cost and lower profit margins.
In frost free areas peas can be planted in autumn and winter. Make sure it will have a growing season of at least 90-115 days before summer temperatures cause the peas to ripen so quickly that a good quality product cannot be harvested. Periods of high rainfall or humidity after flowering should be avoided. In areas where frost occurs, seed should not be planted more than 50 days before the last frost is expected. Weather data over the last 10 years must be used to get a good idea of frost occuring. Temperatures lower than -2°C should also not be expected during this period.