Spinach is an important leaf vegetable, now grown throughout the temperate regions of the world. It is most productive in cool seasons and climates, since heat will cause the spinach to bolt.
Spinach (Spinacia oleracea) is a flowering plant in the family Amaranthaceae, native to central and southwestern Asia. It is an annual plant (rarely biennial plant|biennial), which grows to a height of up to one metre. The leaves are alternate, simple, ovate to triangular-based, very variable in size from about 3-30 cm long and 1-15 cm broad, with larger leaves at the base of the plant and small leaves higher on the flowering stem. The flowers are inconspicuous, yellow-green, 3-4 mm diameter, maturing into a small hard dry lumpy fruit cluster 5-10 mm across containing several seeds.
Spinach is a cool-season crop, and so should be planted either in early spring (just as the soil warms) or in fall. Fall plantings will overwinter into spring for an early crop, and is also well-suited to winter greenhouses and frames.
Planting can be done in situ, in cellpack, or in containers. It is well-suited for growing in flats only for baby greens production.
A distinction can be made between older varieties of spinach and more modern varieties. Older varieties tend to run up to seed too quickly in warm conditions. Newer varieties tend to grow more rapidly but have less of an inclination to run up to seed. The older varieties have narrower leaves and tend to have a stronger (although more bitter) taste. Most newer varieties have broader leaves and round seeds.
There are 3 basic types of spinach:
- Savoy has dark green, crinkly and curly leaves. It is the type sold in fresh bunches in most supermarkets. One heirloom variety of savoy is Bloomsdale. Bloomsdale is also somewhat bolt resistant.
- Flat/smooth leaf spinach has broad smooth leaves that are easier to clean than savoy. This type is often grown for canned and frozen spinach, as well as soups, baby foods, and processed foods.
- Semi-savoy is a hybrid variety. It has slightly crinkled leaves. It has the same texture as savoy, but it is not as difficult to clean. It is grown for both fresh market and processing. Five Star is a widely grown variety and has good resistance to running up to seed.
Rosemary Stanton, in her Complete Book of Food and Nutrition, notes that silverbeet (or chard), is commonly referred to as spinach, particularly in Australia and New Zealand. Hence, there may be some popular confusion between the two vegetables.
Other species called spinach
The name "spinach" has been applied to a number of leaf vegetables, both related and unrelated to spinach:
- Chard (Beta vulgaris - also known as spinach beet or perpetual spinach.
- Atriplex (Orache) - also called "French spinach" or "mountain spinach".
- Chenopodium bonus-henricus (Good King Henry) - also called "Lincolnshire spinach".
In Indonesia, the word bayam is applied both to certain species of amaranth commonly eaten as a leafy vegetable, and to spinach, which is rarely seen, only in certain supermarkets but well known from Popeye cartoons.
- Tetragonia (New Zealand spinach)
- Ipomoea aquatica (Water spinach)
- Basellaceae (Malabar spinach)
- The greens of various nightshade, legume and cucurbit species are also known as spinach, wild spinach, African spinach or morogo (in Southern Africa).
Spinach is often harvested as a baby green or a cut-and-come-again crop. Baby greens can be harvested in as little as 2 weeks after germination.
Spinach loses much of its nutritional value with storage of more than a few days. While refrigeration slows this effect to about eight days, spinach will lose most of its folate and carotenoid content. This is worth considering when purchasing spinach out of season. If the product has been "in transit" (picked, cleaned, shipped and shelved) for more than one or two days it will need to be used almost immediately to have much nutritional benefit. This is in spite of the taste and appearance of the plant which may still seem fine.
Fresh spinach should be cleaned thoroughly and then can be stored loosely in an unsealed bag in the crisper tray of the refrigerator for a few days. Even at 4°C, spinach loses much of its nutritional value by eight days so for longer storage it should be fresh frozen, cooked and frozen or canned. Storage in the freezer can be for up to eight months.
Pests and Diseases
- D. Maue, S. Walia, S. Shore, M. Parkash, S. K. Walia, S. K. Walia (2005). "Prevalence of Multiple Antibiotic Resistant Bacteria in Ready-to-Eat Bagged Salads". American Society for Microbiology meeting. June 5-9. pp. Atlanta. Abstract
- Overview of Spinach from Innvista
- Rogers, Jo. What Food is That?: and how healthy is it?. The Rocks, Sydney, NSW: Lansdowne Publishing Pty Ltd, 1990. ISBN 1-86302-823-4.
- Cardwell, Glenn. Spinach is a Good Source of What?. The Skeptic. Volume 25, No 2, Winter 2005. Pp 31-33. ISSN 0726-9897
- Blazey, Clive. The Australian Vegetable Garden: What's new is old. Sydney, NSW: New Holland Publishers, 1999. ISBN 1-86436-538-2
- Stanton, Rosemary. Complete Book of Food and Nutrition. Australia, Simon & Schuster, Revised Edition, 1995. ISBN 0-7318-0538-0
- Health Benefits of Spinach
- Williams, S.R. (1993) Nutrition and Diet Therapy 7th ed. Mosby: St. Loius, MO
- The nutritional benefits of spinach were discussed in detail in the Skeptic magazine, (Winter 2005).
- Powell, D. and Chapman "Fresh and Risky" Food Safety Network, September 15, 2006