This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
When sowing our last piece of winter Spinach, we had not enough of the Prickly to sow what ground was required, as we are expected to have it every day in the year. The ground was finished with the Round-seeded or Summer variety. This was on the 3d September. It all came up at the same time, and for about two months little difference could be seen but as the weather got colder, the Prickly shot ahead a long way, and from it we were gathering long before the other was ready. As soon as the days began to lengthen, the Round variety, which had done little all winter, made a start and grew very fast, soon getting far before the Prickly, the leaves being large, thick, and fleshy. It has also stood longer without running to seed than the other; and now, 12th June, we could pick quantities if required: but all will have to be cleared to make room for other crops. I am not aware that the Round variety has been tried for winter, but it has done so well this spring that I mean to sow again for next spring.
This is sown between the rows of Peas at each sowing of the latter. It is a mistake, often made, to sow Spinach thickly, as when crowded it is not so good in quality, and is more liable to run to seed. Thinning out, if performed in good time, is right enough; but then this is frequently left undone till it is too late. Spinach is one of the best of materials in which to pack either vegetables or flowers.