Begin by selecting an early variety of the best quality. Some time towards the end of January the sets are packed closely in shallow boxes, one layer deep only, and these are placed in full daylight safe from frost, but are not subjected to heat in any way. Having started the sets into growth in full daylight, proceed with the preparation of the ground. This must be light, warm, dry and rather rich without being rank. If a length of wall is available, and perplexity arises concerning suitable soil for the early Potatoes, seize all the sandy loam that has been turned out of pots, and having mixed it with as much leaf-mould and quite rotten manure as can be spared, lay the mixture in a ridge at the foot of the wall. As walls do not anywhere run in such lengths as to provide for all the early Potatoes that are wanted, select a plot of ground lying warm and dry to the sun, and having spread over it a liberal allowance of decayed manure, and any light fertilising stuff, such as the red and black residue from the burning of hedge clippings, turf, and weeds, dig this in. The ground being ready, it is lined out in neat ridges two feet apart, running north and south. These ridges must be shallow, rising not more than six inches above the general level. On every fourth ridge sow early Peas that are not likely to grow more than two and a half to three feet in height. This being done in February, the land is ready for Potatoes in the first week of March. Plant on the fine stuff laid up next the wall in the first instance, and then on the ridges, where there is room for three rows of Potatoes between every two rows of Peas. In the process of planting, it will be advisable to rub off all the weak eyes and thin out those on the crown, two or three strong eyes being quite sufficient. This can easily be accomplished as the sets are laid into their places in a shallow drill opened on the top of the ridge. The sets may be put a foot apart, and have four inches of fine soil over them. Prick the ground over with a fork between the rows, leaving it quite rough, but regular and workmanlike. The Peas will soon be visible and require attention. Draw a little fine earth to them, and stake them carefully with small brushwood. If snails and slugs appear, give dustings of lime or soot, and as soon as possible supply stakes of sufficient height and strength to carry the crop. By the time the Potatoes begin to show their shaws the Peas will constitute an effectual shelter for them against east winds, and it will be found that the morning frosts that are often so injurious to Potatoes in the month of May will scarcely touch a crop that has the advantage of this kind of protection. But to that alone it is not wise to trust. One serious freezing that blackens the shaws will delay and diminish the Potato crop. Therefore, as the green tops appear, cover them lightly with fine earth from between the rows, and if necessary repeat this, always allowing the leaves to see daylight. When a sharp frost occurs, it will be advisable to cover the tops with a few inches of light dry litter in just the same way that a bed of Radishes is protected. There are many other methods of saving the rising shaws. A plank on edge on the east side of a row will suffice to tide through an ordinary white frost. Mats or reed hurdles laid on a few stout pegs will also answer admirably, but care must be taken that the plant is not pressed down, and the covering must be removed as soon as the danger is over.
Crops grown under walls will be ready first, and those in the beds will follow. Spaces between the trees of a fruit wall may be planted with Potatoes, without injury to the trees. Those grown on the south face of a good wall will be ready for table three weeks in advance of the earliest crops in the open quarters. But east and west walls may be made to contribute, and even north walls are useful, if planted a week later and a little deeper. In all cases the sets should be put close to the wall to enjoy the warmth, and dryness, and shelter it affords. When the crop is lifted, the soil specially laid up for it may be taken away, or scattered over the border. But the bulk will be so slight that it will not matter much what becomes of it. However, in a new place with a clay soil it may be prudent to remove it, and keep it ready as an aid in seed sowing, for there are times and places where a little fine stuff is worth a great deal to give a crop of some kind a proper start.
The main crop, as the source of supply for fully nine months out of twelve, deserves every attention. Potatoes are grown with advantage on so many diverse soils, and in such unlikely climates, that the plant appears, on a casual consideration, to be altogether indifferent to its surroundings. But it is none the less true that for the profitable cultivation of this crop certain conditions are absolutely essential. Among these an open situation and a well-drained soil are perhaps the most important. To this might be added favourable weather, because a bad season frustrates every hope and labour. Having an open situation and a well-drained soil, it is much to be preferred that the soil be of a deep, friable, loamy nature; in other words, a good medium soil, suitable for deep tillage, but neither a decided clay, chalk nor sand. A fertile sandy loam, lying well as regards sunshine and drainage, may generally be considered a first-rate Potato soil, and excellent crops have also been grown on thin soils overlying chalk and limestone. So again, fine crops are often taken from poor sandy soils, and from newly-broken bog and moss, as well as from clay lands that have had some amount of tillage to form a friable top crust. But when all is said the fact remains that the ideal soil for Potatoes is a deep mellow loam, and, failing this, preference should be given to calcareous and sandy soils rather than to clays or retentive soils of any kind.
Manures.—Much prejudice prevails against manuring land for Potatoes, and where the soil is good enough to yield a paying crop, it will be prudent to do without manure, and to dress generously for the next crop to restore the land to a reasonable state. Still it is the practice of many of the most successful growers for the early market to manure for this crop, and in some instances the manure is laid in the trenches at the time of planting. Generally speaking, land intended for Potatoes should be deeply dug, and, if needful, manured in the autumn. About twenty to thirty cartloads of half-rotten manure per acre may be dug or ploughed in to as great a depth as possible, consistent with the nature of the subsoil and the appliances at command. In breaking up pasture with the spade, bastard trenching will as a rule prove advantageous. The land is lined off in two-feet breadths, and the top spit of the first piece is removed to the last piece, which will often be close at hand by the rule of working a certain distance down and back again. The under spit will then be well broken up, the manure thrown in, and the top spit of the next piece will be turned in turf downwards, making a sandwich of the manure. If this is done in autumn, there will be a mellow top crust produced by the spring, and the best way to plant will be in trenches, unless the land is very light, in which case the dibber may be used.
As light lands are often profitably devoted to Potato culture, and more especially to the production of first-class early Potatoes for the markets, a few words on their management may be useful here. If on the light land there is a choice of aspects, by all means select the plots that slope to the south-west; the dangerous aspects are north and east. The ground should be ploughed up in autumn and left rough, but it is not economical to manure light lands in autumn. At the time of planting, the furrows should be cut with a plough fitted with a double mould-board, and the manure spread evenly along them previous to laying in the sets. A good dressing per acre will consist of fifteen loads of farmyard manure, and four cwt. of artificials, consisting of one and a half cwt. of guano, two cwt. of superphosphate of lime, and half a cwt. of muriate of potash. When the sets are laid, cover them by splitting the ridges with the plough. If planted early in March, the crop should come off in time for Turnips, for which the land will be in good heart, and the seed should be sown as quickly as possible after the clearing of the Potatoes.
Preparing the Sets.—Among the many subjects that open out before us at this point are the selection and preparation of the sets. Why are smallish tubers chosen in one case and planted whole? and why, in another case, are large tubers chosen and divided before planting, to make two or more sets of each? Because there is a principle on which sound practice rests, and it is this: the number of shoots starting from any one growing point must be limited, for if they become crowded the crop will be less than the land is capable of producing. Keeping this principle in view, we proceed to remark, in the first place, that carefully selected seed of moderate size may be planted as it comes from the store without any preparation whatever, and with a fair prospect of a profitable result. But certain varieties produce few tubers of seed size, and when large they must be divided in such a manner as to insure at least two eyes in each set. As a matter of fact, profitable crops are grown in the most simple way; the seed is neither sprouted nor disbudded, and with a well-made soil and a favourable season, the return is ample, and all claims are satisfied. Potato-growing entails much labour, therefore it is important to distinguish between tasks that are necessary and those that are optional.
But where the time and strength can be found for first-class cultivation, it should have the preference over the rough and ready methods that are satisfactory on a large scale. Exhibitions of Potatoes are for the most part sustained by persons who can find the time to do things with extra care, and they have their reward in their crops as well as in their prizes, for what may be styled Exhibition culture consists simply in growing the crop in the best possible way, and planting many sorts where in any other case a few would suffice. Here, then, on the best plan, we begin with sets most carefully selected, to insure true typical form and colour, and these are, some six weeks or so before planting time, put in shallow boxes or baskets, one layer deep, to sprout in full daylight, but quite safe from frost. In the first instance a number of sprouts appear, and a large proportion are rubbed off. The object of the cultivator is to secure two or three stout, short shoots of a green or purple colour; the long white threads that are often produced in the store being regarded as useless. When large sets are employed, they are allowed to make three or four stout shoots, and at the time of planting—not before—these sets are cut so as to leave to each large piece only one or two good sprouts or sprits. As for the smaller sets that are not to be divided, it is common practice to cut a small piece off each of these at the time of planting to facilitate the decay of the tuber when it has accomplished its work, for having nourished the first growth the sooner it disappears the better. Thus, with a little extra trouble, sound tubers have been prepared for planting, and the main reasons for taking this extra trouble are doubtless fully apparent. The best seed possible is wanted and the most suitable soil; these two items forming the first chapter. By sprouting the seed time is gained, which is equivalent to a lengthening of the season. By limiting the number of shoots an excess of foliage is prevented. Where the shoots are crowded the tubers will not be crowded, a few strong shaws with all their leaves exposed to the air and light being capable of producing better results than a large number contending for air and light that are insufficient for them all. And finally, by cutting the sets, whether to divide them, or simply to hasten their decay, we insure that they will not reappear with the young crop as useless, ugly things.
Distances for Planting.—The distance at which the sets are planted is of importance, for a crop too crowded will be of little value. But the ground must be properly filled. By wasting only a small space in each breadth, or in the spaces between the sets, the total crop will be many bushels short of the possible quantity. The guiding principle must be to allow to each plant ample room to spread, and absorb the air and sunshine, in accordance with the character of the sort and the condition of the soil. A considerable proportion of the losses from disease may be traced to overcrowding in the first instance; the tangled haulm being rendered weak through want of air, and then becoming loaded with water, and in contact with wet ground, the disease has made havoc where, had the management been founded on sound principles, there might have been a vigorous healthy growth. If a doubt arises, it is safer to allow too much rather than too little space, and in this respect the exhibition growers are very liberal. They often place the rows of strong-growing varieties four feet or more apart, and allow a space of three and a half feet for the more moderate growers. Even then, with good land, in a high state of preparation, the shaws sometimes meet across the rows, and enormous crops are lifted. For a very comprehensive rule, it may be said that the distance between the rows may vary from fifteen inches for the early sorts of dwarf growth, to forty inches for the vigorous-growing late sorts. Between these measurements, for varieties producing medium haulm, a distance of twenty-six to thirty-six inches may be allowed on good ground. The distance between the sets must in like manner be determined by the growth, and will range from nine inches for crops to be dug early, to sixteen or twenty inches for the robust kinds. The medium maincrop Potatoes will generally do well at twelve inches apart. Much, however, depends on the season, for when great space is allowed, and the season proves warm and showery, there will be more large tubers than the grower will care for; whereas, if planted somewhat closer, the crop would be smaller and more uniform in size. When planted, the tops of the tubers should be about four inches below the surface.
Time of Planting.—Under favourable conditions, it is possible to plant on a warm dry border as early as mid-February in very sheltered districts, but a supply of protecting material must be instantly available in the event of severe weather. As a rule, however, the opening of March is soon enough to plant early crops out of doors, always provided that the soil is light and the situation warm, but where these conditions do not exist it will be safer to wait until the middle of the month. Maincrops may be got in at the end of March and during April, according to the locality and the character of the soil. In any case, it is better to defer the operation for a week or so than to plant in heavy wet ground which quickly consolidates, making it impervious to air and unsuitable for root-penetration. Excellent crops may also be obtained by planting in July, preference being given to quick-growing early varieties. Old tubers only should be used and these must be carefully stored until required for planting.
Method of Planting.—On light soils, in a sufficiently dry condition, the dibber or planting stick may be used, but on heavy ground it is not satisfactory. A good method of planting for all classes of soil is to draw out a V-shaped drill of the requisite depth, place the sets into position and lightly return the earth. Another plan which is largely adopted is to insert the sets in the trenches as made during the operation of digging the ground in spring, a garden line being used to obtain the accurate alignment of the rows.