This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The hard - shelled fruits variously known as Hazel Nuts, Filberts, and Cob Nuts are produced by a somewhat hairy or downy shrub or small tree (Corylus Avellana), the wild form of which is a native of Great Britain and Ireland, but is also found throughout Europe, North Africa, and temperate Asia. The leaves are roundish heart-shaped, pointed, deeply and distinctly veined, and doubly toothed on the margins. The male and female flowers are borne on the one-year-old shoots, but are quite distinct from each other. The male flowers are borne in conspicuous drooping pale-yellow catkins, 1 to 2 in. long, from January to March. The female flowers are comparatively inconspicuous, but are much more important from the nut grower's point of view. They are borne on the same shoots as the male catkins, but in fat stalkless buds above them. About February and March these buds (which are plumper than the ordinary wood buds) begin to break, and several bright crimson thread-like styles protrude, as shown in the drawing (fig. 394). They are then ready to be fertilized, and some of the pollen from the male catkins, being blown about by the wind, is sure to come in contact with the tips or stigmas of the crimson styles. In due course the young nuts begin to swell, and ultimately form the "nut" enclosed in . the leathery husks. It is essential for the grower to bear this little piece of natural history in mind, especially at pruning time. If the young shoots containing the catkins and female flowers are cut away, it means no fruit.
The Cob or Filbert may be looked upon almost as a crop peculiar to Kent. It may, however, be, and is, grown in other parts of the kingdom, and gives a fair return as a market-garden crop in suitable situations.
A sandy loam, seated on a chalky or limestone subsoil, is considered the most suitable soil for nuts. It should be prepared by subsoil ploughing and harrowing some time before the planting period, so as to have it in a clean condition. If the soil is too rich, there is a danger of too much wood being produced at the expense of fruit. A soil of this description, however, might be rectified by an annual dressing of lime (20 to 40 bus. to the acre) or by the application of 5 to 10 cwt. of basic slag early in January. On land where rampant growth is observable, it would be well not to apply stable or farmyard manure for a few years.
Fig. 394. - The Hazel (Corylus Avcltana), showing male drooping catkins, female flowers, and nuts.
Nut trees are usually grown on a stem 1 1/2 to 2 ft. high, from which the branches are trained outwards so as to form a kind of skeleton vase. In this way the leaves and shoots are exposed fully to the ripening influence of air and light. The planting should be done in October or November, and young bushes will cost about 30s. per 100. They are often planted 10 ft. apart each way, but better results are likely to be obtained at 12 ft. apart each way, giving about 300 trees to the acre. The intervening space may be cropped with Gooseberries, Currants (about 750 to the acre), or Raspberries,.- or vegetable crops until the nut trees require all the ground to themselves. No returns can be expected for the first five or six years from the nuts, but once in bearing the 300 trees ought to yield an average crop of 10 to 12 cwt. that is, about 3 1/2 to 4 lb. of nuts to each plant. At 6d. per pound the gross returns would vary from £28 to £33 per acre. The diagram, representing roughly 1/4 ac, shows how nuts and bush fruit like Gooseberries or Currants should be planted.
If standard Apples, Pears, or Plums are planted at 36 ft. apart, about thirty-three will be required to the acre, and these will come into bearing in due course without interfering with the nut trees. When the Apples, Pears, or Plums are established, the returns from them would be anything from £10 to £20 per acre, according to the crop and the prices prevailing. The annual cost of cultivation might be reckoned about £15, and after allowing for rent, rates, taxes, marketing, etc, the net profit would vary from £10 to £20 per acre.
Pruning - This is an important operation, and should only be performed by experienced gardeners. A good strong pruning knife should be used, or if it is necessary to use a saw for thick wood, it will always pay to trim the rough surface afterwards with the knife, otherwise the shoot is apt to die back. As the nuts are borne on the young wood, as shown in the illustration, the best of this should be retained, and only the weak shoots cut out. The centre of the tree should always be kept open and clear of shoots and twigs. As the plants are rarely allowed to grow more than 6 or 8 ft. high, it will be necessary to shorten back some of the strong leading shoots in winter, always cutting to a bud pointing away from the centre. In this way new young wood will develop lower down the main branches, and will in due course bear fruit. After this, such shoots, being no longer useful for fruiting purposes, may be cut back to a couple of buds at the base, so as to give rise to fresh shoots, which will eventually be subjected to the same process.
Gooseberries or Currants.
...Standard Apples, Pears or Plums.
The best kind of nut for market purposes is "Kentish Cob" or " Lambert Filbert". It grows vigorously, and bears large thick-shelled nuts in clusters of three or four, sometimes more, sometimes less, according to the season. There are over twenty other kinds of nuts, of which, perhaps, Webb's Prize Cob Filbert is the best for trade purposes.