Seedlings should be grown in a well-aerated medium, which has good water holding capacity and at a pH of around 6.5. Generally, peat, bark and vermiculite mixes are used. Media problems typically include excessive tannins and low air filled porosity, which results in poor drainage and the build up of green mould. The medium should be pre-enriched and the seedlings should be fertilized. For optimum germination, the seedling trays should be placed in a germination chamber, at 20 °C with high relative humidity. The seedlings should be moved to the tunnel at
the first sign of germination. The ideal temperature for seedling cultivation is 20 °C.
Seedling management is a critical factor in cabbage production, as the following factors related to seedling production may result in physiological disorders in cabbage:
– Incorrect sowing time.
– Cold temperatures, particularly below 7 °C.
– Cold grown seedlings.
– Over-fertilization of seedlings.
– Oversized seedlings at transplant.
– Temperature differences between the seedling nursery and the farm.
Spacing:
It is recommended that 26 – 30 000 plants/ha is planted for the loose head market. Higher plant populations raise the average yield per hectare, but the heads are smaller. For the bagging or chain-store / pre-pack market a density of 35- 45 000 plants/ ha is recommended. However it must be noted that the population of a cabbage field per hectare for a commercial grower can vary and planting is dependent on what the specific market needs and available resources are.
The following guidelines explain the recommended spacing and requirements for the various
markets.
Loose head/ Hawker market
• Head size, weight & hold-ability are important features.
• Plant density of ± 26 – 30 000 plants / ha.
• Plant spacing of 60 – 70cm X 60cm.
Bagging / chain-store/ pre-pack market
• Quality, uniformly filled heads, firmness and color are important.
• Yield per hectare and uniform cut.
• Plant density of 35 – 45 000 plants / ha.
• Plant spacing of 45 – 55cm X 60cm.
For baby cabbage, varieties have a smaller head size and the population can be increased. A plant spacing of 25cm (in row) X 25 cm can be used as a guideline.
