How to Grow Spinach

Botanical Name: Spinacia oleracea

Plant Type: Hardy Annual

Spinach, Spinacia oleracea, is an annual with separate male and female plants, and is a member of the family Chenopodiaceae, being a close relative of the beets. Originating in Asia, it has been cultivated in China for the past 2000 years and reached Europe some 400 years ago. While it has somewhat of a reputation of being unpopular with children, it remains an important leaf vegetable, which is rich in vitamins and high in iron.

Deep green, crunchy leaves rich in the antioxidants vitamin C and E are the reward for growing this extremely hardy crop.

Varieties

Individual varieties of spinach vary in a number of important characteristics. Today’s fast-growing varieties have been developed with an emphasis on resistance to bolting (running up to seed) in hot weather and tolerance of cold. There has also been the development of more tasty varieties, which are less bitter due to a lower content of oxalic acid. Older varieties tended to have narrow leaves, prickly seeds, and a strong flavour, and are prone to bolting, hence they are less frequently seen in cultivation today. Broad leafed, round seeded varieties are less tasty than their narrow leaf counterparts but show better bolt resistance and are currently in favour with gardeners.

‘Bloomsdale’ is an heirloom variety of good flavour that also is bolt resistant. A relative of the common spinach called New Zealand spinach, Tetragonia tetragonioides, is very similar in flavour and requirements, and can be grown through summer to provide a source of spinach at a time when the traditional type is unavailable.

Warm season spinach such as Spinach ‘Perpetual’ (Beta vulgaris) produces a continuous supply of greens throughout the warmer months with a spinach x silverbeet flavour. Spinach ‘Malabar Red’ (Basella alba ‘Rubra’) is a decorative heat-loving climber with twining red stems and succulent edible spinach-like leaves.

Cultivation

In general, spinach requires the same type of preparation and management as lettuce and silverbeet. Sowing time is critical to avoid bolting. Even with bolt-resistant varieties, spinach plants will bolt and run up to seed in hot conditions and periods of long day length. In southern areas, it is grown as two crops in spring and autumn, while in the central and northern part of the country, it becomes a dry- season crop. In cooler areas, plants should be established in full sun, but if attempting to lengthen the harvest season in other areas, they can be established in partial shade to slow bolting.

Spinach seed will germinate at soil temperatures from near freezing to 30°C, and at 10°C will germinate in a week.

After a few weeks, thin plants to a spacing of 20 cm. Spinach is sensitive to variations in soil moisture, and plants should be mulched and regularly watered. Autumn-sown crops can be successfully over-wintered (held in the ground), although, if there is the chance of severe frosts, they should be protected with a light covering of straw or hay.

Sun: Full Sun           

Pollination: Wind Pollination

Soil: For best results, spinach prefers well-drained soil that is slightly acidic to slightly alkaline. Gardeners with very heavy, clay type soils should consider improving the structure through the addition of gypsum and sand and by hilling up beds to improve drainage.

Growing from Seed

Sow: either sow direct into well prepared soil or sow into seedling trays for transplanting into the garden or larger pots when hardened off. Seed should be soaked overnight prior to sowing and should be sown to a depth of 2cm with a spacing of 8cm to 10cm.

Ease of Germination: medium

Germination Temperature: 2-30°C

Germination Time: 5-10 days

Spacing: 20 cm

Harvest: 40-60 days

Yield: 2kg/metre

Maintenance and Additional Care

Spinach likes lots of water so make sure they don’t dry out.  Once the weather warms, water your spinach in the heat of the afternoon to cool it down and keep the soil cool for the evening.

Leafy green crops need plenty of nitrogen so give you spinach a liquid feed with an organic fertiliser rich in nitrogen fortnightly. Mulching spinach helps to keep the soil moist and cool

Companion Planting

Good companions:  Strawberries, beetroot, onion, eggplants, leeks, lettuce, peas, radish

Bad companions: potatoes

Pests and Diseases

In general, few pests or diseases cause problems with spinach. In foggy or dewy conditions, downy mildew can affect plants, but it can be controlled with copper-based sprays. Aphids and mites can sometimes be a problem and can also be controlled with sprays.

Growing in Containers

Spinach grows well in pots and containers. Always use a premium potting mix when growing in containers. Water morning and night to maintain adequate soil moisture and liquid feed regularly for quick growth and to avoid bitterness

Harvesting

Harvest leaf by leaf, almost to the ground, and they then resprout. Depending on growth, the first leaves can be harvested as early as eight weeks after sowing, starting with a few of the outer leaves. Later on, the stem can be cut a few centimetres above the ground to harvest all the leaves because the plants will resprout.

Seed Saving

Seed Longevity: 5 years

Isolation Distance: 3000m+ - fine netting or bagging encouraged for seed purity

How to Save Seed: harvest spinach seed stalks when the majority of the seed cluster has turned brown. The fully mature seed can be progressively stripped from the plant as they mature.

Tips and Tricks for Success

• seeds germinate in soils near freezing to 30°C. However, to prevent spinach from growing straight up to seed, sowing time should avoid long daylight hours and hot weather.
• harvest leaves as baby spinach as early as 8 weeks after sowing, and then decapitate the plant leaving the pink-white steams that will resprout. Spinach appreciates being sown after peas or beans for the most delicately flavoured of leaves.
• some partial shade in hot regions can extend the harvest period by discouraging it from bolting.