Propagation is from seed
Some growers do sow directly but the most successful way to plant broccoli is by making seedlings in seed trays and once the seedlings are about 150 mm in height then they are transplanted into the field.
Broccoli plants should be spaced 40 to 50 cm apart in rows that are 50 cm apart. This is between 30 000 and 40 000 plants per hectare. It is also good to stagger the broccoli plant rows as this allows the plants better light and ventilation through the plants.
Broccoli seeds are normally sown in late summer when temperatures start dropping. In South Africa this is from late February in cooler regions to early May in the warmer areas.
Approximately four to five weeks after the seeds have been planted the broccoli seedlings should be ready to be planted out. In South Africa planting takes place from early April to the beginning of June. In some areas where spring and early summer temperatures are low enough early spring plantings can also be done if the crop can be harvested before the hot weather arrives.
Broccoli is a faster grower than the other Brassicas like cabbage. Broccoli can be harvested as quickly as six weeks after planting out of the seedlings. When planted where the most growing takes place over the cooler winter months, this can slow down the development and this stretches the growing period to eight to ten weeks from planting of seedlings. The most important factor dictating the growing period and broccoli harvest is to make sure to harvest before the heads start to flower.
A soil analysis should be done. Broccoli is a medium to heavy feeder. Combine your normal fertilizer program with manure and/or compost as broccoli likes soils rich in organic matter.
A general recommendation is that before planting, disc plough in a minimum of 800 kg of 2:3:4 to ensure that your broccoli gets a good start. Some growers prefer an application of chicken manure prior to planting. Broccoli is a fast grower, so it is essential that there are enough nutrients available in the soil during the first weeks of growth as this promotes the formation of a healthy, central flower head.
Applications of 350 kg LAN per hectare along the plant rows can be given at two weeks after planting and a further 400 kg LAN per hectare at four to five weeks after planting.
Do not fertilize too close to your expected harvest date.
Irrigate broccoli seedlings once a day until they are ready to be planted out. Irrigate and moisten the area that is to be planted so that seedlings can be planted into moist ground. Once planted immediately irrigate so that plants can settle into their new environment. Thereafter irrigate between 25 mm and 35 mm of water per week depending on temperature, rainfall and soil type.
By Louise Brodie