Climate, soils and varieties
In Perth, best quality spinach is produced from May to October but it is marketed all year. In summer, some varieties quickly produce flower stalks. For summer production, choose a variety with good bolting tolerance.
Spinach is fairly resistant to frosts while high temperatures cause yellowing of older leaves.
Spinach can be grown on a wide range of soils, providing they are well-drained. It is very sensitive to acid conditions. To correct this, add lime where soil pH in calcium chloride is less than 6.0.
To avoid disease, rotate crops to give more than four years between spinach crops on the same ground. This is rarely achieved commercially as spinach is harvested at an immature growth stage (baby leaf) for the salad market. Turnover times are much quicker than in the past and many more crops can be grown on the same land in a given period.
Commercial vegetable varieties change constantly with changing consumer preferences. Before planting, check with seed company representatives and your destination market for current varieties.
Planting may be conducted all year but March to August will produce the best quality spinach.
Spinach is rarely transplanted. It is sown directly into a well-prepared level bed. For ‘baby leaf’ production, sow seed 1 to 2cm deep in rows 10cm apart to achieve a final stand of about 40 plants per metre of row. In a commercial bed layout of 15 rows in a 1.5m wide bed, this equates to about 600 plants per square metre. Spinach for culinary purposes is sown at about one sixth of this density and the crop allowed to fully mature. It is not economic to thin spinach after emergence. However, too high a density may increase problems with leaf disease.
Some growers have successfully grown spinach in a hydroponic lettuce-type nutrient film technique system. One of the advantages is that it is marketed with no sand in the leaves. There have been problems providing sufficient aeration to the roots and the nutrient solution must be replaced more regularly than with other hydroponic crops.