Propagation
Sweet corn propagation is by seedPlanting Method
Sweet corn seeds should be planted 4 cm deep to ensure that the top soil temperature can reach 16°C to 20°C for effective germination as soon after planting as possible.
It is important to plant uniformly at this depth to ensure that the sweet corn plants grow uniformly. This is important for harvesting. Planting is done with mechanical planters to ensure uniform stand of plants. On smaller plots planting can be done by hand.
Spacing
Sweet corn plants should be spaced 20 to 30 cm apart in rows that are 80 to 100 cm apart. This equates to between 40 000 and 60 000 plants per hectare.Sowing Time
In South Africa sow the maize seeds from August to March or even early April in warm areas with late winters and no frost.Growth Period
Sweet corn takes 10 to 12 weeks to reach harvest readiness if the weather is warm and conditions ideal. If the growth period of sweet corn experiences cooler temperatures then the corn harvest can be delayed and could require up to 14 weeks.
The flowering stage and formation of the tassels at the top of the corn plant takes place at about 6 to 7 weeks from planting and harvest readiness is 3 weeks thereafter.
Under ideal conditions, new sweet corn variety selections have been harvested at between 8 and 9 weeks with some producers being able to have two crops per year.
Fertilization
At planting, apply 800 to 1000 kg of 2:3:2 (22) N:P:K mixture per hectare. This can be done when levelling the plant area immediately before planting. This enriches the soil with the three main macronutrients Nitrogen (N), Phosphate (P) and Potassium (K).
Three weeks after planting, when the sweet corn plants have established themselves, apply additional Nitrogen in the form of 400 to 500 Kg of LAN per hectare to boost growth and strengthen the plant.
Before flowering at about 6 to 7 weeks into the growth period, a further 400 to 500 kg of 1:0:1 (29) should be applied, as this provides equal amounts of Nitrogen for growth and Potassium for good corn ear and kernel formation.
Irrigation
Irrigate immediately after planting the sweet corn seed to settle the seed. Do not over irrigate as this will cool the soil and hamper germination.
Once the sweet corn plants have started to grow and the roots start to establish themselves, increase the irrigation to between 25 to 35 mm per week throughout the growing period.
Remember that sandy soils will drain faster and could require more and more frequent irrigation as the sweet corn crop develops and soils with higher clay content could require less and less frequent irrigation scheduling during crop development. Do not irrigate for the week before harvest.
Always monitor soil moisture content frequently either by the installation of soil moisture meters or by hand with a spade or augur.