Site and soil | Varieties | Sowing | Growing on | Picking | Troubles
As interest has increased in the Mediterranean diet and in the cookery of the region, spinach has come back into the limelight. Once disregarded as an unappealing vegetable, it is now being used more creatively in cookery, and fresh spinach from the garden is unbeatable.
Spinach is grown for its tasty leaves which can be used cooked or raw in salads. Chard, spinach beet, perpetual spinach or leaf beet are related to spinach but are not the same thing and do not have the same flavour. These are grown as substitutes because they are easier to grow. New Zealand spinach is not even related to spinach, but is also often mentioned as an substitute. Spinach is a good source of iron, vitamins and antioxidants.
Site and soil
Spinach is a fast-growing leafy crop and needs a good sunny site. It can tolerate some shade during the sunniest time of year and indeed this can be beneficial as it helps to reduce the stress on the plant during hot, dry weather. It could be located in the shadow of some sweet corn or tall peas or broad beans, for instance, which is not heavy shade but cools the soil. Being a leafy crop, the plant needs rich soil with plenty of nitrogen to grow leaves well.
The plants must not get a check or they tend to go to seed very readily and for this reason the soil must be open, richly fertile and retain moisture well. The soil can be enriched with garden compost or well-rotted manure. General fertilizer, such as 10-10-20, or 18-6-12, can be applied at 80 to 100 grams per square metre if the soil is poor, but this would not be necessary if the ground has been well fertilized for previous crops such as potatoes. Do not over-feed either as this coarsens the flavour.
Most of the seed companies offer a range of spinach varieties. The older varieties were divided into spring-sown types, which were not completely hardy, and summer-sown hardy varieties to stand over winter. These boundaries have been blurred by further breeding and hybridisation and the newer varieties are more reliable. They have been bred for greater resistance to going to seed, and while this can still happen, the problem is not as great as with the old varieties. Modern varieties are less bitter in flavour too.
Of the older varieties, ‘Sigmaleaf' was a standard and gave good results generally. ‘Bloomsdale' is relatively easy to grow, ‘Scenic' has good resistance to mildew and can be sown spring or late summer. ‘Tetona' is also mildew resistant as is ‘Tirza', which is also slow to bolt and ‘Lazio' resists bolting too. ‘Tornado' is good for sowing in the warmer months, being more tolerant of hot conditions. ‘Bordeaux' has red-veined leaves of good flavour and adds a touch of colour to salads. Oriental spinach varieties are also becoming available, such as ‘Oriento', which is of upright growth and has very good resistance to bolting.
Spinach seeds can be sown from spring to autumn. The seed is normally sown where it is to grow - it is not transplanted as this can cause bolting. The seeds can be sown thinly in rows about 30 centimetres apart or 45 centimetres from neighbouring vegetables. Usually just a single row of a few metres is sown and repeated every three to four weeks to maintain a continuous supply of fresh leaves. The seedlings are thinned to about 15 centimetres apart in the row and the thinnings can be used in the kitchen. Alternatively three seeds can be sown at that spacing and thinned carefully to one seedling when small.
Spinach seeds can be sown in cell-trays or small pots to bring on young plants to be planted outdoors, or they can be kept in a greenhouse or tunnel to have an early supply. The first sowings outdoors usually can be made in March or April and repeated. The summer sowings can run into trouble if the weather is hot and dry, especially on light soil. Further sowings can be made in July and August to have plants going into winter, but they need to be well grown beyond seedling stage, or they will struggle in winter.
Spinach needs even growing conditions and tends to flower, or ‘bolt', when disrupted. Choose the site carefully and prepare the soil well. Sow in good conditions. Germination is quicker and better when there is some heat in the soil. However, spinach does not like hot, dry conditions and watering will often be necessary, although watering alone will not prevent bolting. If growth is slow due to dull weather, an application of liquid feed will help. The later-sown crop will be of better quality if it is covered with cloches or low polythene tunnel. Harsh weather can damage the foliage, or at least reduce its quality.
Spinach is usually picked by pulling off individual leaves, working evenly along the row. The picking can start quite early when the plants are only ten or twelve weeks old and ‘baby leaves' of excellent flavour can be picked. The constant picking of leaves helps to reduce bolting. Alternatively, some growers prefer to cut away all the leaves at once and allow them to re-grow.
Because spinach is a quick-growing crop and repeat sowings are usually made, it usually gets to harvest stage without much trouble from pests or diseases. Bolting is the main problem and this is related to growing conditions, not a pest or disease. Downy mildew causes yellowing of the upper surface with mould underneath, and the leaves rot. Most new varieties have at least some resistance. Watch for greenflies too.