This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The Carrot has been developed from the wild British Daucus Carota, a hardy biennial of the Umbellifer family. As a farm and market-garden crop it is highly valued for its taproots, the coarser and larger roots being used for cattle food, while the shorter and more highly flavoured kinds are preferred for human use. As a farm crop over 11,000 ac. are cultivated in Great Britain, the principal Carrot-growing counties being Cambridge (over 2000 ac), Lincoln (over 1500 ac), and Bedford (about 1000 ac).
The soil for Carrots should be deeply cultivated, and be of a sandy loam. Rough cloddy soil is quite useless, as the roots like to be closely packed round with a nice rich friable mould into which they can penetrate without much trouble. Manure is best applied in the autumn, especially if only partially decayed, as heavy manuring in spring is apt to develop coarseness and irregularity. On the other hand, the lack of well-decayed manure or humus will be a great drawback, especially during dry hot summers, when the roots will begin to crack and split owing to the absence of moisture in the upper layer of soil.
For early crops the Shorthorn and stump-rooted varieties, like "Early Shorthorn" (fig. 467), "Early Market", "Early Nantes", etc., may be sown in drills about 6 in. apart in February on warm, sheltered borders, afterwards thinning the young plants out to 3 or 4 in. apart. In this way over 300,000 plants would go to the acre. The crops should be cleared by the end of May or early in June. Maincrop varieties, like "James's Intermediate Scarlet" (fig. 468), etc, are sown from March to the end of April, and still later the "Long Surrey Red", but more space is required for these. About 20 tons of carrots may be secured from an acre of land under ordinary methods at a cost of about £10 per acre, but with more intensive methods as much as 40 tons may be looked for, even with intermediate varieties. It will pay to use the hoe early in the season, not only to keep weeds down, but also to encourage quicker and more succulent growth, and to liberate the supplies of potash, phosphoric acid, and lime, which are taken up so largely from the soil.
Fig. 467. - Carrot - Early Shorthorn.
Fig. 468. - Carrot - James's Intermediate.
Where large supplies are grown for winter use it is usual to store the roots in the same way as Beetroot, in clamps, from which they may be drawn as required.
Carrots are often attacked in badly cultivated soil by wireworms, leather-jacket grubs, etc, which infest the roots and destroy them. Such ground pests are best got rid of by deep cultivation and the aid of birds, and by dressing the soil a few weeks in advance of sowing with kainit at the rate of 4 or 5 cwt. to the acre. The Carrot Aphis is likely to be troublesome in weedy soils, and may be checked to some extent by the application of soot to the foliage after a shower of rain or a heavy dew By keeping the ground well tilled and free from weeds these pests will however, be reduced to a minimum.