TOMATO-CULTURE.

New Zealand Journal of Agriculture, Volume XV, Issue 3, 20 September 1917, Page 136

TOMATO-CULTURE.

W. H. TAYLOR,

Horticulturist

Having grown tomatoes in the open ground ’for- forty consecutive seasons and under glass for more than twenty years I can at least claim to have had opportunities for observation. I have long believed that the tomato is generally cultivated along wrong lines. Because it is a succulent, strong-growing plant it is thought that “it must require a lot of feeding.” As well might we say the same of the American. aloe, a plant that can make its enormous growth and send a flowering-spike like the mast of a boat, twenty or more feet high, out of a bed of rubble on a dry hillside. Again, the herbaceous calceolaria is a succulent plant having an appearance that causes the belief that it must require a lot of water : as a matter of fact, the numerous failures that occur in attempts to grow the. plant are because too much water is given—it really requires a quite moderate supply.

With the tomato the aim -should be to check growth, not to foster a gross habit. My own practice for years past has been to use no animal manure, which I believe causes blight except under dry conditions of soil. . Manure is safe to use in a dry season but fatal in a wet season, and. we cannot forecast the weather. I never water outdoor tomato-plants, but have never failed to secure an excellent crop, and have experienced only two attacks of blight during. the past twenty years, and then only slight attacks and from recognized causes. Regarding glasshouse culture, I am convinced 'that most of the losses incurred by growersand they have been many and great —were caused by a too-wet condition of soil and atmosphere. Several years ago the Department was called on to investigate the cause of nonsetting of fruit. Experiments were carried out in houses lent for the purpose, and in collaboration with the owners, and it was eventually agreed that the. cause of the trouble was too much moisture. . My own conviction has long been that the ideal conditions for tomatogrowing should include warmth, sunshine, and rather dry conditions, and that given these conditions there would be no blight. - My own experience has strengthened this opinion.

CULTURE UNDER GLASS.

Apart from raising the plants, and excepting in places . where severe frosts occur, tomatoes can be grown under glass without artificial heat and be ready for market in December, or in extra warm

places in November. To secure the earlier supply the plants should be set out in July.

RAISING THE PLANTS.

The seed should' be sown about the second week in May. Those who have not a heated greenhouse will find a hotbed covered with a frame answers admirably for this purpose. The manure should be turned over several times, and well shaken to remove all knots. Two or three weeks should be given to the preparation 'of the manure, as it is desirable to remove all rankness and to secure a gentle and dry heat. The ■ seed should be sown in shallow boxes too much soil encourages. deep rooting and soft plants. Scatter the seed rather thinly, as crowded seedlings are weak. Pricking-off should be done as soon as the seedlings are large enough to ■ handle. The boxes for pricking the plants into should be shallow, the depth being limited to enable the roots to quickly take possession of all the soil, and also to economize labour ; 3 in. deep inside measurement is ample. Allow the young plants a space of about 2| in. each way. No more water should be given than suffices to keep the plants growing, and this will be comparatively little at the season in question. The soil in the boxes should be mainly fairly good loam, with a little very old manure, and sand if required to keep it open ; a small proportion of wood-ashes is also useful. To prepare the boxes, first put in a layer of stable manure that is in a half-decayed littery condition, and not in a wet state. After being pressed down the manure should nearly half-fill the box. Heap the box* up with soil and stroke off the surplus with a piece of batten, so as to leave it level-full; press the soil moderately firm with a piece of board, and then mark out the lines for the seedlings by pressing in a strip of lath ,at the required distances. The boxes of seedlings should be returned to the hotbed ; bottom heat encourages root-growth ; abundant ventilation will ensure firm and stocky plants. When sufficiently grown'the plants should be placed in the house to harden for a week or two before they are planted. • ' • • . .

FRAMES FOR RAISING THE PLANTS.

If the plants are to be raised on hotbeds, or later for outdoor culture, frames will be required. It may be as well to say here that except for use on hotbeds frames are not recommended where large numbers of plants are to be raised. Low-roofed, narrow houses are more economically worked, are built at less cost, and are less costly to maintain in repair. A convenient size for a frame would be one that would carry lights 6 ft. by 3 ft. ■ To carry lights of those dimensions the ends of the frame should be 5 ft. 9 in. wide, the back ft. high, and the front 1 ft. high. The sides should be 1 in. totara or

matai boards, well primed. with red-lead, and painted with two coats of white-lead and oil; or if preferred they may be creosoted, which is less costly and equally preservative, though the appearance is not so good. Corner studs of 3 in. by 2 in. or 4 in. by i|in. must be put in, these being cut level with the bottom boards. Rafters of 3 in. by 2 in. must be put on to carry the lights where two meet. Before nailing these in their places run a good plough-groove down each side to carry the water that will run off the sides of the lights. Between the grooves nail a 1 in. strip to keep the lights in place. -If the frame is to be portable, two lights are the most convenient size. If they are to remain as fixtures there may be any number of lights. The frames should be elevated a little above the surrounding ground. The best plan is to stand them on a row of bricks ; the frames then stand firm and true, and if the bricks are given a good coat of tar before the frame is placed on them it will preserve the wood and shut out woodlice.

DRAINAGE.

■ J Perfect drainage is absolutely essential. The lower the watertable the better ;■it . should not be within 3 ft. of the surface. It should be comparatively easy to add to the depth of the soil by carting sufficient to raise the surface inside the house, and this would give the additional advantage of raising the level above that outside. ,

SOIL PREPARATION AND MANURING —FIRST YEAR.

Any fairly good garden soil will grow tomatoes, but new soil is to be ‘ preferred. . There is always danger of soil long in cultivation containing disease-spores, and this is especially the case where the land has been long cropped with vegetables. There, is no need, however, to avoid such soil if the exigencies of the case render its use advisable ; but no opportunity should be lost to add new soil, if . only a few inches deep. The manuring of new soil is easier than old, as its requirements can be more easily estimated; old soil may be already rich in the properties that induce green growth. Soil taken from an Old upland pasture, cut out about 3 in. deep and stacked turf downward till the grass is dead, is the best new soil to add. Prior to planting; the soil should be deeply dug and left with a rough surface, so that it may be well aerated.

. Before planting give a dressing of superphosphate and bonedust, i oz. of each per square yard, and sulphate or - nitrate of potash, | oz. per square yard. Potash is at the present time expensive and difficult to obtain,- and may be omitted if a dressing of wood-ashes sufficient to cover the soil is given. The ashes, however, should have been kept quite dry, as if rain has fallen on -them a proportionate

quantity of potash will have' been washed out, according .to the extent of the exposure.' If the soil is poor in humus sulphate of ammonia, | oz. per square yard, may be given, but . otherwise should not be used, as it merely promotes green growth, an excess of which makes the plants unduly susceptible to blight-attacks.

Constant treading on the soil —unavoidable in attending to the plants—is likely to make the surface hard. This condition of soil should be prevented. All necessary attendance can be given by walking on alternate rows, and the soil in these rows can be protected by a mulch of dry littery manure.

PLANTING.

It is desirable that the soil be made somewhat firm before planting. - Soil that is very loose is quickly dried by. evaporation, so that much watering, would be necessary, and excess in watering should be avoided.. Loose soil also promotes growth of a flimsy nature. The nature of the soil may be such as to ensure the necessary firmness by merely levelling it. over with a rake, but if it is very light it should be well trodden, down or, better, have a light roller passed over it. <

If the plants, have been well, prepared the roots should carry practically all the • soil of the boxes, including the manure that was placed on the bottom of the latter. The best way to handle the plants is to knock one end off a box, when the whole contents can be slipped off and the plants pulled apart without injuring the roots. To plant, first brush aside dry crumbs of soil on the surface with a trowel, dig a hole amply large enough for the ball of roots and deep enough to admit 2 in: or 3 in. of the stem above the ball. Cover the roots with the soil that was dug out, pressing it firmly over the ball. Unless the soil be very dry no water should be given at this time.

J In regard to distance apart in planting, the general tendency appears to be to plant too closely. Close planting does not necessarily produce more fruit ; it certainly demands more watering, and incidentally creates a moister atmosphere and favours attacks of blight. It is suggested that 24 in. by 12 in. is close enough for small houses, and that 30 in. by 12 in. is a better distance to adopt for large houses. The closer the plants are to each other the more watering is necessary and the greater the risk from blight-attacks. A little extra space between the plants also permits a better circulation of - air and more sunlight on the plants. The securing of these conditions should be sufficient compensation .if there were no other benefits, but it would be reasonable to expect a sufficient increase in weight of fruit per plant to bring the aggregate . crop at least equal to the weight that would be obtained by closer planting.

TRAINING THE PLANTS

An iron bar, in. by i in., should be screwed to the rafters along each side of the house from end to end, about 6 ft. 3 in' from the ground (so as to give head-room) ; then light wires stretched from these across the house above where the rows of plants will be. Over the centre path a stronger wire should be stretched from end to end of the house on the same level as the cross-wires. A few lengths of strong wire attached to screw-eyes fixed to the apex of the roof and hooked on to the centre wire. will prevent the cross-wires from sagging. From the cross-wires suspend a length of binder-twine for each plant ; the lengths of twine should reach the ground, and may be fixed, by tying each to a short peg of wood thrust in the ground. As an alternative, the twine may be lightly tied to the bottom .of the plants, but of course this cannot be done until the latter have grown somewhat. As the plants grow they should be twisted round the twine, no tying being needed. The plants should, pass round the twine northward from east to west ; they will then retain their position, that being the direction in which all climbing-plants travel upwardsnamely, with the sun. ■ . ;

PRUNING.

The plants should be restricted, to single stems, all side shoots with an exception which will be described being pinched out as soon as they are seen. ‘ The top of each plant should be pinched when the required number of . bunches of . fruit have been secured, five or six bunches being usually -considered sufficient the exception mentioned above is thus explained. The reason for growing tomatoes under glass is, of course, to get early fruit, and it is important that the plants set the lowest bunch of - fruit. Some strains, however, will not do this, and in such cases it is good practice to allow a shoot from the base of the plant to extend till it shows a bunch of fruit, and stop it above the next two leaves. By this means an extra bunch per plant of early fruit is obtained on each plant, this in a large house amounting to hundreds of pounds weight. The leaves on the main stem should be retained. The best plant for glasshouse work is one that has leaves of medium size. Some varieties have very gross leaves, and these should be reduced to medium size by cutting off about one-third of each, the formation of the leaves rendering this possible without impairing their functions. When a bunch of fruit has been cut. the leaves immediately above it should be removed.. Leaves that .are below fruit are useless, and also become worn out ; their removal aids the circulation' of air and relieves the plants.

VENTILATION

It is now becoming generally understood that a close moist atmosphere and ’ blight - are synonymous —one . following the other. The means for ventilation should be ample. Large houses should have a door at each end ; both can be opened during quiet weather,

and one during rough weather. , With two doors neither top nor side ventilators need be extensive. The‘amount of ventilation given and the manner of applying it should be ruled by circumstances ; there can be no hard-and-fast -rule; ' Early-forcing houses require most, care,

and naturally in such cases ventilation should be almost entirely from the top. With unheated houses the position is quite different. It is not so much increased heat that is sought for as protection from they inclemencies of the weather, and consequently a more equable temperature. Extremes in temperature should be avoided, and at times this' will require all the ventilation that can be applied. Not only is free ventilation safe, it is very beneficial to the plants, giving them solidity of substance and rendering them blight-resistant. If the atmosphere is kept moderately dry, air can be allowed to pass freely through the plants, and they will benefit by it; but this would not be safe with a wet house, a state which I say should not exist.

WATERING.

.With a view to preventing a great change of temperature in the soil, which would cause a check, watering should be done when the soil is at its coldest, and naturally this will be early in the morning. The soil will..then have the benefit of increasing sun-heat, will gradually warm up, and most of the evaporation will be over before closing-time. The house can . then be closed in a fairly dry state, will retain warmth longer, and the atmosphere will remain moderately dry through the night. However dry the house may be, a certain amount of-moisture is bound to gather during the night; it will, in fact, never be absolutely dry. . The amount of water necessary is a much-debated phase of tomato-culture, but, as already indicated, I have no hesitation in saying that in general practice far too much is given. Experimental- work has proved that the tomato thrives in very dry soil, and is then quite free from blight. The plants should never be syringed except for the purpose of applying insecticides or fungicides. -

FERTILIZING THE FLOWERS.

An overmoist atmosphere prevents the . dispersal of pollen. It should be remembered that house plants , are practically deprived of the aid of wind and insects, which are the chief pollen-carriers in open-air culture, where also the pollen is dry the greater part of the time. The atmosphere of a house should be dry during the greater part of the day, so that the pollen may be easily dispersed.' This process cis assisted by a slight agitation of the plants, to be effected in a simple manner by smartly rapping them .with a light cane, or by drawing the cane quickly along the rows of twine, precisely as is done in vineries to help shy setters. The time to carry out this operation is the middle of a fine day. .

PREPARATIONS FOR THE SECOND YEAR.

Preparations for the second year may be said to begin > with the clearing-out of the old plants, and this should be done in a thorough manner. The roots of the plants, should be forked out, the twine cut from the wires, and the whole removed and burned. The ashes from the burning should be returned to the soil, thus replacing a considerable, portion of the mineral matter taken out by the plants. The soil-should be dug up and left rough as before, so as .to expose ’ as much surface as possible, and the doors and ventilators opened wide, abundant light and air having a purifying effect on the soil. It is well known that the excreta from the roots of the tomato-plant are poisonous to future plants of the same kind. In open - air cultivation the poison is not present in sufficient quantity to affect a second crop, but it'is injudicious to attempt to get . a third crop from the same soil. In glasshouses the plants are grown closer together, and the toxic secretions are therefore proportionately larger. Aeration of the soil must have some cleansing effect, but it seems advisable to supplement this by growing some vegetable crop that, may take up some of the deleterious matter. Field-peas are suggested 1 for the purpose, as they are deep-rooting, rapid in growth, and decompose quickly after being turned under. Peas, however, will not do much good unless they are made to grow strongly, and as the soil will be dry if the tomatoes have been properly treated, it should be well flooded with water, the peas to be sown when the water has " settled down. A dressing of superphosphate, 2 oz. per square yard, or 4 oz. of basic slag, should be given to ensure good growth .in the peas. The green crop should be -turned under in time to allow' for the violent fermentation to take place before planting. Carbonic-acid gas, which is." generated by fermentation of green matter, is poisonous to sprouting seeds, and is likely to be. injurious to soft-wood plants; If it is possible to ' add some new soil, as advised earlier, there can be no doubt that will be more beneficial than anything else, and such an addition should supplement the green crop. , ' .

CULTIVATION IN POTS

Tomatoes are successfully grown in pots, a method that is convenient for the production of early fruit where the house is furnished with : plant stages and they cannot be planted in the ground. In a span-roofed structure the plants may be trained on . wires under the roof, ; but. it is not worth .while to attempt it if other plants which require heavy shading are grown in the house. Tomatoes will not succeed ; under heavy shade light shading will not hurt them, but if they are properly grown they require and are . best with' very little.

A lean-to house is better adapted to pot culture oh a small. scale than a span-roofed house, provided it faces nearly north, so. as to secure the greater amount of sunshine. The upper portion, of the glass roof should be left unshaded. A wooden trough, 12 in. by 12 in., can be used in place of pots, and is really much better. As the roots of the plants will be confined to a small space, methods of 'cultivation must be very different .to those of ground culture. ' The soil used should be good' turfy loam, with a little very old manure', and bonedust equal to a 5 in. potful to a barrow-load of compost. The loam should be broken by hand, not riddled, as that would remove the fibre, which it is important to retain. The only drainage required is provided by shaking most of the soil from some of the turf, and placing the latter in the bottom of the pot. The whole contents of the pot will thus be rooting-material, which is an important point, for were it otherwise larger pots would be required.

Plants for this method of culture should have been raised in small pots, first in 3 in. size, then moved to 5 in., planting in the larger pots as soon as the points of roots show freely through the soil. The larger pots should be only half-filled with soil, the ball of the young plant placed on the soil, and sufficient soil added to cover it, and pressed very firm. No more soil should be added until the plant is a foot or so above the pot, when it should be filled up. The plants will require frequent watering, and while the fruit is swelling liquid manure should be given two or three times a week. After the pots have been filled with soil new roots will push from the buried portion of the stem, and the plant will be greatly strengthened, so much so that the increased vigour of the plants may demand more root-room. ' This can be given by laying strips of fibrous turf round the rim on the pot and filling up with soil. Roots may come through the top of the soil, in which case . give them a mulch of dry horsedroppings ; these may be piled up, as water will pass freely through them. During twenty years’ continuous practice in pot • culture I never experienced an attack of blight. Probably the . elevation of the. plants from the surface of the soil, thus' securing . a dryer atmosphere, accounts for this immunity. ' ✓ .. ■

[Open-air culture will be dealt with in the next issuAof the Journal. — Ed.]

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