1911 Encyclopædia Britannica/Spinach
SPINACH (Spinacia oleracea), an annual plant, a member of the natural order Chenopodiaceae, which has been long cultivated for the sake of its succulent leaves. It is probably of Persian origin, being introduced into Europe about the 15th century. It should be grown on good ground, well worked and well manured; and for the summer crops abundant watering will be necessary.
The first sowing of winter spinach should be made early in August, and another towards the end of that month, in some sheltered but not shaded situation, in rows 18 in. apart — the plants, as they advance, being thinned, and the ground hoed. By the beginning of winter the outer leaves will have become fit for use, and if the weather is mild successive gatherings may be obtained up to the beginning of May. The prickly-seeded and the Flanders are the best for winter; and these should be thinned out early in the autumn to about 2 in. apart, and later on to 6 in. The lettuce-leaved is a good succulent winter sort, but not quite so hardy. To afford a succession of summer spinach, the seeds should be sown about the middle of February, and again in March; after this period small quantities should be sown once a fortnight, as summer spinach lasts but a very short time. They are generally sown in shallow drills, between the lines of peas. If a plot of ground has to be wholly occupied, the rows should be about 1 ft. apart. The round-seeded is the best sort for summer use.
The Orach or Mountain Spinach (Atriplex hortensis), a member of the same order, is a tall-growing hardy annual, whose leaves, though coarsely flavoured, are used as a substitute for spinach, and to correct the acidity of sorrel. The white and the green are the most desirable varieties. The plant should be grown quickly in rich soil. It may be sown in rows 2 ft. apart, and about the same distance in the row, about March, and for succession again in June. If needful, water must be freely given, so as to maintain a rapid growth.
The New Zealand Spinach (Tetragonia expansar), natural order Ficoideae, is a half-hardy annual, native of New Zealand, sometimes used as a substitute for spinach during the summer months, but in every way inferior to it. The seeds should be sown in March, on a gentle hot-bed, having been previously steeped in water for several hours. The seedlings should be potted, and placed under a frame till the end of May, and should then be planted out in light rich soil. The young leaves are those which are gathered for use, a succession being produced during summer and autumn.