The first consideration is what size head you want, as this is determined by spacing. For the most common type of cabbage plant the market requires, you won’t lose yield at any population between 35 000/ha to 65 000/ha, provided the growing conditions are favourable. Spacing affects size and time to maturity. The wider the spacing, the larger the heads, provided the variety has the genetic potential to produce large heads. At the same time, the wider the spacing, the earlier the maturity. This is usually incidental as head size is the important consideration.
What the markets want
Generally, urban markets require a slightly smaller head than those sold to the bakkie trade. Sometimes there’s no limit, and the larger the head the better. Sometimes the price per kilogram gets higher as the size increases. Determine the size for your target market and regulate spacing to achieve it. If you space too widely when the market prefers a medium cabbage, you’ll have to harvest too early, and so lose yield potential.
When planting on flat ground instead of beds, it’s good to keep rows about 60cm apart and regulate size by the distance apart in the row. It’s unnecessary to make sure they are uniform on the square – I’ve found no benefit in this. But much will depend on what’s convenient for you.When planting three rows in a bed, the middle row gets shaded from both sides. With some varieties and a high population, many plants become stunted and take extra long to mature.
You can space the middle row plants further apart in the row to even this out. It’s often better to plant two rows with the plants closer together in the row. Yield per hectare is better when planting the whole land as opposed to beds, but beds are necessary in some conditions, especially when frequent heavy rain is likely.
When planting into a black-rot-prone area in late summer, opening up the spacing will change the micro-climate slightly, increasing air movement. This will make conditions slightly less favourable for black rot, and since the plants will mature earlier, you can harvest before the black rot has reached a more destructive stage.
Planting at wider spacing
Certain varieties are more suited to wider spacing. Some varieties with spreading frames are better suited to making larger heads, and tend to become uneven in size when planted at high densities. For speciality cabbages, including baby types that are wrapped in punnets, very close spacing is required for economic reasons. You can play around a little to achieve the perfect size for your market – some prefer slightly smaller heads.
Some of these types can also be spaced further apart to accommodate a larger size, up to 1kg. This is a small market and some farmers produce smaller cabbages from commercial plantings than planting a variety dedicated to this size. Examine your spacing closely to ensure it’s exactly right for the market requirement and maximum yield.
Bill Kerr – 016 366 0616 or e-mail [email protected].