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.
Parsley is of such ancient culture in this country that, so far as I am aware, the period of its introduction cannot be correctly assigned. It is said to be a native of Sardinia, and to have been introduced into England about the beginning of the sixteenth century. According to botanical authorities it is not a native of this country, but it has nevertheless naturalised itself in several parts of the kingdom, though the great favour in which it is held by hares and rabbits will prevent its ever spreading itself in a wild state.
Generally speaking, Parsley is of easy culture, but in some soils it is peculiarly subject to the attacks of a small white worm at the root, which, interferes much with its growth till late in summer, and in some cases it is destroyed altogether. Some say that if transplanted while in a young state it escapes this pest. I have known it so subject to die out on some soils, that the only way to produce it in quantity is to take out a trench the depth and width of a spade, and fill it up with fresh loam and then sow the seed. The middle of March is a good time to sow for the summer supply. When sown in drills, they should not be less than a foot apart, and to get fine foliage the plants should be thinned out to 6 inches apart.
In many cases Parsley is sown as edgings to paths'or walks in gardens, and to this there is no particular objection. For late autumn and winter supply, a good plan is to transplant the necessary quantity into a border where the protection of frames can be given in winter, and it can be planted close to the base of garden-walls, where in case of frost or snow it can be protected with mats or any other coverings, but it is best under glass both for fine produce and convenience.
A second sowing should be made in April for a winter supply, when it is intended to stand without being transplanted.
The more curled the leaf, the better it looks for garnishing purposes; it is also finer in flavour than the plain leaves. Wherever seed is saved, the best curled plants should be selected for the purpose.
 
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