Raising Bedding Plants for the Flower Garden

New Zealand Journal of Agriculture, Volume 81, Issue 1, 15 July 1950, Page 75

Raising Bedding Plants for the Flower Garden

THE raising of bedding plants at home for use in the annual borders is a fascinating part of .gardening. In view of the simplicity and cheapness of the practice, why it is not carried out much more widely is hard to understand. In this month’s article for the flower gardener, C. K. Ellis, Horticultural Instructor, Department of Agriculture, Dunedin, describes , the method of raising annuals to the stage where they are placed in their flowering positions in beds and borders. The commoner diseases of the flower garden and the sprays in general use are also discussed.

HARDY ANNUALS are usually sown where they are to grow and flower and are not difficult subjects for either amateur or professional gardeners. However, the more tender, half-hardy annuals are normally sown in seed-pans, pots, or boxes and are given the protection of a cold frame, greenhouse, or sheltering wall. Cleanliness Essential The importance of sterilising soils for seed raising should never be overlooked, and the methods of sterilising available to the amateur are referred to toward the end of this article. However, sterilisation of the soil alone is not sufficient, for putting clean soil in dirty containers is a waste of effort. If new boxes are to be used, they should first be painted with some type of wood preservative (but not creosote) which will prolong the lives of the boxes and discourage harmful fungi. Old boxes, pots, and pans must be thoroughly cleaned and washed free of mosses, algae, and fungi. If the time is available, old materials can be partially sterilised by spraying them with 4 per cent, formalin. Benches, floors, and tools should be clean. • . ■ . These precautionary steps should always be taken before sterilised seed composts are placed in the receptacles. The Soil Mixture Garden soils vary so much that recommending a simple standard mixture which will give adequate results is difficult, but no mixture could be better than the following, which may be used for both seed sowing and the subsequent pricking out of the seedlings: 2 parts by bulk of sterilised medium loam; 1 part by bulk of peat, leaf mould, or good, pulverised, composted material; and 1 part by bulk of coarse -sand. All constituents should be passed through a fin. sieve, and to the mixture should be . added IJoz. of basic superphosphate and foz. of carbonate of lime to each bushel of the compost.

The components must be mixed thoroughly. A good way is to spread the loam evenly on the floor, spread the peat on top of it, and finally spread the sand, with which the lime and superphosphate should have already been mixed The mixing should then be done with a shovel, strip by strip As the mixture is turned it should agam be spread m an even layer, and the operation must be repeated three times before the soil can be considered properly mixed. The “structure” of the soil in a seed-box mixture is imnnr+ant a ■+' ' . u -r, j A mixture can be considered ready for use only when it has the correct water content and that can be judged by taking a handful of the soil and compressing it slightly by clenching the fist. When the fist is reopened the compost should more or less retain its shape in the ball, with perhaps a crack or two in it, and should leave no moisture or sticky muddiness on the fingers. Should the soil crumble on release of the grip, it is too dry; if it remains in a sticky mass and leaves moisture on, the fingers, it is too wet.

The mixture must be in the correct condition before it is used. Sowing the seeds and endeavouring to correct the condition later is useless. The boxes should be no more than 4in. deep greater depth of soil is not necessary should have the boards on the bottom spaced a little to allow free drainage of water. A layer about Jin. thick of any organic material such as spent hops assists drainage. The box is filled loosely with the compost until it reaches above the level of the sides, and the level is reduced to that of the sides by striking off the surplus with a piece of board. The soil is pressed down firmly at the edges and at the corners with the fingers or a rammer, thus ensuring that it does not dry out rapidly near the outside of the box and that water does not cause depressions in corners. Then the rest of the soil may be firmed down with a piece of wood in such a way that the surface is level when the job is finished. If the surface is not level, water will run into the lower areas and cause uneven watering, which greatly affects germination and growth of the seedlings. The soil surface should be about Jin. below the edges of the box to allow room for covering the seeds and for subsequent watering. If pots or pans are to be used, drainage is specially important. Each receptacle' should contain a large crock, concave side down, over the drainage hole, with several smaller crocks over and around it. . A thin layer of fibrous material on top of the crocks prevents the soil being washed down, which would hinder drainage and cause - slumping of the soil surface. These receptacles are filled with compost in the same way as are boxes.

Sowing the Seeds

In normal circumstances, if the instructions given so far are carried out and the seed is of reasonably good quality, germination ■ can be expected to ,be good. Therefore, all z seed should oe sown thinly. The sowing may be done in a variety of ways: More, experienced growers usually sow seed directly from the packet, but it may be sown pinch by pinch or even shaken over the box from a salt or pepper shaker. Even spreading of the seeds is essential, and if rhe seeds are large, it is worth while to sow them one' by one in some sort of geometrical pattern. Damping-off is less likely to spread in well-spaced seedlings. Usually only one variety is. sown in each receptacle, but if small numbers of plants are required, boxes may be divided into sections by placing strips of bamboo across the surface, or by inserting in the soil strips of glass or wood which just reach across the box, thus reducing the possibility of the seeds being mixed when they are watered. Alternatively, small drills may be made with a stick or with a finger and each variety sown separately. Varieties should be labelled at this stage. Seeds should be sown to a depth about three times their diameter. A sieve with a mesh no finer than jin. should be used to spread the covering over the seeds, for finer soil tends to crack or cake after being watered. The covering material need not necessarily be soil; river sand or other gritty material, other than oyster or shell grit, is just as good provided it is passed through a fine-meshed sieve.

Before and after Germination After the seed has been sown sheets of glass should ;be placed over the boxes to prevent the escape of moisture, and a sheet of brown paper should be placed over the glass to prevent the entry of bright sunlight and to assist in reducing evaporation. The boxes should be placed in a warm, shaded position in a greenhouse or garden frame or in a sheltered position in the open. The boxes must be inspected daily, but the glass should not be turned frequently, for this removes moisture and hastens the drying out of the receptacles.

Immediately ' the seeds have germinatedthat is, when the seed leaves appearthe paper should be removed to prevent the seedlings becoming drawn. Soon afterward, provided the weather is favourable, the glass should also be removed. The seedlings require close attention at this stage. If the soil starts to dry out, water should be applied carefully with - a fine rose and the seedlings covered with scrim or newspaper to protect them from the fiercest rays of the sun, but this cover must be removed immediately the danger has passed. Then is the time to watch closely for “damping-off” fungus, which is referred to under the heading “Fungous Diseases.” Pricking Out the Seediings 'Recent experiments have shown that seedlings are best pricked out at the earliest possible stage. The earliest convenient time with most annual border plants is the seed-leaf stage. The boxes to be used should be filled in the same way as for seed sowing and with the same compost. An accurate pattern should be marked out on the surface of the soil -to show the position into which each seedling is to be pricked out. A few hours before the plants are to be pricked out, or even the night before, the seedling boxes should be watered thoroughly to minimise root damage when the seedlings are being lifted from the soil. The soil should be loosened with a knife or • dibble and the seedlings removed from it carefully, one by one, held gently with the thumb, and forefinger by one of the seed leaves. They must never be held by the stems because they are exceptionally easily bruised, and bruised areas are usually attacked first by fungi. The dibble —a short, cone-shaped piece of wood—is, used to push a hole in the soil of the pricking-out box and the seedling is lowered into the hole with its roots vertical and the seed leaves just above the soil level. The hole is filled in by pressing the soil gently to the roots with the dibble and the fingers. As each box is filled it should be watered lightly with a fine rose. Once this operation has been completed there’ is little to do except to keep a close watch for damping-off or other diseases, to keep the soil moist, and to maintain adequate ventilation about the plants. As soon as the plants are big enough they should be planted out. Flants held in boxes too long tend to become starved and lose, their vigour, which they seldom regain under normal conditions. Garden Work for August Begonia tubers can be started' into growth during August. Inspect each tuber carefully, cut away any diseased or rotted portions with a sharp knife, and dust the cut surfaces with 'flowers of sulphur. Half bury the tubers in a good, fibrous soil in boxes, sprinkle them with water, and place them in a warm positionin a greenhouse if possible. Do not water them. . too much.

Cultivation of . flower, borders at this lime of year is important, for the soil is likely to become caked after latewinter and spring rains and winds. Shallow pricking over with a fork is the safest method because it minimises the danger of root damage. ... Dahlias can be increased by cuttings, which can be taken soon. Select the varieties to be increased, place the tubers in boxes of soil, and stand them in a greenhouse or frame. New shoots suitable for cuttings will soon appear. Gladioli will not be planted in large numbers until September, but August is- the time to prepare the soil. They do best in a deep, well-drained soil in a sunny, sheltered position. Hydrangeas for pot culture should be started into growth, in - August by putting them in ■ a warm place and watering them well. The top of the soil in each pot should be scratched away carefully and be replaced by a topdressing of new potting soil. Seed of a wide range of bedding plants may be sown in greenhouses or frames in August. Among them are antirrhinum, salvia, Cineraria maritima, ageratum, ten-week stock, clarkia, cynoglossum, french marigold, petunia, viscaria, asters, Livingstone daisies, nemesia, gilia, and celosia. Shrubs which flower on the new season’s wood should be pruned in August. They should be cut hard to keep them shapely and to encourage as many new shoots as possible. Among the shrubs and climbers to be treated thus are Clematis • jackmani, dogwoods, coral trees, willows with coloured' bark, Ceanothus spp. (deciduous), Hydrangea paniculata, Buddleia variabilis, and Spiraea japonica Anthony Waterer. Bacterial Diseases Important bacterial diseases of ornamental plants in New Zealand include fireblight and citrus blast. Fireblight is the more serious, though citrus ’ blast affects a much wider range of plants. Fireblight First reported in the Dominion in 1919, fireblight (Erwinia amylbvorus) has since spread throughout the country. It attacks ornamental trees and shrubs of the Rosaceae family, including Crataegus, Cotoneaster, and Pyrus species. The bacteria overwinter in margins of cankers and in fruit spurs, becoming active in spring. Insects become contaminated with organisms when feeding and carry them to flowers and young shoots of plants in the vicinity. Infection of spring and summer shoots develops rapidly and often the bacteria are extruded in small beads of “ooze.” These ooze droplets attract insects and form additional sources of infection during spring and summer. The foliage of attacked ■ branches usually turns brownish and dies, the leaves remaining whole and attached to the branches or twigs. The ooze is most likely to be detected in spring and early summer. ' The home gardener who finds infection among his tree's should first eliminate cankered branches and destroy badly infected trees and shrubs. In the case of a particularly valuable specimen the canker may be removed

by cutting away the infected bark and infected wood plus a wide margin of apparently healthy tissue, and sterilismg the wound with a mixture or 4 oz. of mercuric chloride, g pint of concentrated hydrochloric acid, and 11 pints water. The instruments used during the operation should also be stemlised and all infected portions removed should be destroyed. When the stemlising solution has dried out . co , m pletely the wound should be painted over with liquid coal tar.

Citrus Blast Though not as serious as fireblight because it causes less damage and is more readily controlled, citrus canker (Pseudomonas syringae) causes a blackening of terminal shoots and of leaves or parts of leaves, and is sometimes confused with fireblight infection, though diseased shoots dry out more quickly and leaves become brittle. Infection usually follows injury of host plants by frosts, hail, or cold winds, and consequently young growth is most seriously damaged. Large stems and branches are not affected. As infection occurs on young growth during cold weather, it is advisable not to force luxuriant growth in 'early spring or late autumn. Young growth . can be protected adequately by applications, of 3:4:50 Bordeaux ■ mixture. Fungous Diseases Black Spot ■ Usually appearing in early summer, the first indication of the presence of black spot of roses (Diplocarpon rosae) is purple-brown spots on the foliage. Defoliation may follow heavy infection, and in this case all fallen x leaves must be gathered and burnt, as the spores overwinter in the soil, and a dressing. of Boz. of slaked lime per square yard applied to the soil surface during winter. During July or August the dormant plants should be sprayed with 5:4:50 Bordeaux mixture, repeated about 3 weeks later provided growth has not begun. While the foliage is on the plants they may be sprayed with lime . sulphur at the rate of 1J tablespoons ■ to 1 gallon of water, or with 3:4:50 Bordeaux mixture if it is feared that the nlants may be susceptible to limesulphur injury. The developmental cvcle of the fungus occunies about 14 days, so. that spraying should be repeated every 10 days until the disease has disappeared. , .

Mildew of Roses Probably the most common disease of roses is mildew (Sphaerotheca sp.). Grey spots on the leaves are the first indication of its presence, these spreading rapidly until they cover the leaves and finally the young shoots, with a resultant loss of vigour and bloom. Some varieties of rose resist attack by mildew, but most of ’ the softer, quicker-growing types are very susceptible. Pruning, which keeps the plants open to the circulation of air and permits entry of sunlight, does much to prevent spread of the disease. Spraying with the lime-sulphur mixture recommended for black spot is useful as a controllant, as is dusting with flowers of sulphur. Damping-off of Seedlings The fungi given the popular name damping-off fungi (Pytnium, Rhizoctonia, and other species) are those which attack seedlings, often severely, at or about ground level. Humid conditions encourage, the growth of these fungi, and their effect on seedlings is to cause decay of the stem, usually in a confined region about the base, so that ultimately the plant topples over and dies. Partial control can be effected by the use of Cheshunt compound, the preparation of which is described under the . heading of “Sprays.” Rusts Many species and strains of rusts (Puccinia spp.) are present in New Zealand gardens. . Their presence is evidenced by rusty spots on the leaves, which eventually wither and die, the plants often being debilitated seriously. Too many rusts are prevalent in flower gardens to allow a complete control schedule to be laid down, but undoubtedly the most satisfactory method of attacking them is spraying with one of the proprietary preparations of colloidal sulphur or lime sulphur. Burgundy mixture or Bordeaux mixture used at intervals of 10 to 14 days after infection has appeared, or

lime sulphur (1:150) plus colloidal sulphur (21b. of 50 per cent, to 100 gallons’ of water), also gives satisfactory control in most cases. Botrytis Rot Another fungous disease which attacks the stems of seedlings and young plants, botrytis rot (Botrytis spp.), first shows itself by a softening of the stem, followed by blackening and bending, and finally by the growth of a white, fluffy mould. When seed-, lings are attacked the best control measure is the use of Cheshunt compound. If larger plants are attacked, it is best to remove and destroy those infected and spray the remainder with Burgundy or Bordeaux mixture. Sclerotinia Causing rapid decay, sclerotinia rot (Sclerotinia spp.) attacks many plants, including petunias, zinnias, stocks, and wallflowers. Dead plants are usually black, but are covered by a white growth. Cheshunt compound is a useful preventive, but affected plants should be removed and burnt.

Adequate cultivation and correct spacing of plants are important factors in that they help to keep down humidity. Mildew of Larkspurs ' Larkspurs, delphiniums, and several related plants become infected with a mildew (Erysiphe sp.) which Covers the leaves and stems with a white mould. This disease has a very marked effect on the vigour of the plant, and dusting with flowers, of sulphur is the . most convenient means of control. Fungicidal Sprays Cheshunt compound is prepared from copper sulphate and ammonium carbonate, finely powdered, in the proportions of 2oz. of copper sulphate to lloz. of ammonium carbonate. These two chemicals should be mixed thoroughly and stored in an airtight jar. To prepare a spray loz. is dissolved in a little hot water and 2 gallons of cold water added; it should be used immediately. Burgundy mixture, a mixture of copper sulphate and sodium carbonate (washing soda), is used instead of Bordeaux ■ mixture mainly because it is easier to prepare and more pleasant to handle. However, it is less efficient than Bordeaux mixture as a fungicide and is likely to cause more damage to foliage, being incompatible with lead arsensate. The spray is prepared by mixing in a wooden vessel 6oz. of copper sulphate and Boz. of sodium carbonate with 5 gallons of water. Bordeaux mixture: The normal winter strength is usually written as 5:4:50, which indicates that the formula is 51b. of copper sulphate, 41b. of hydrated lime, and 50 gallons of water. The normal summer strength is 3:4:50. The spray is prepared by pouring three-quarters of the required quantity of water into a wooden mixing vessel and dissolving the copper sulphate in it; this should be stirred thoroughly to ensure that the bluestone is dissolved completely. ■ The

hydrated lime is weighed out and mixed to a thin paste with water. This is poured slowly into the mixing vessel and the rest of the water added, The mixture should be stirred thoroughly all the time and again before it is used. Lime sulphur: The preparation of lime sulphur is too complicated and unpleasant a task to make it worth while for the home gardener, who is well advised to buy one of the reliable brands available if he requires this mixture. Its chief use is in controlling certain pests, such as red spiders and scale insects, while also fulfilling the requirements of a fungicide. Sulphurs are recommended mainly for the control of mildew and rust, the most satisfactory form for spraying being colloidal sulphur. This cannot be prepared by the home gardener, but reliable brands may be bought. Colloidal sulphur for spraying should be Sn?of e wato° f 2 ‘° 4lb - Per 100 gallons oi wdiei. Stomach-poison Insecticides ■ Such chewing insects as pear slug, bronze beetle, and leaf roller are attacked by sprays containing stomach poisons. Arsenate of lead to be used for spraying should contain 33 per cent, arsenic pentoxide, of which no more than 0.2 per cent, should be water solüble. The usual dosage is 1-Jlb. of powder or 31b. of paste per 100 gallons of water. Foliage of flowering peach trees is likely to be injured by arsenate of lead sprays, so a spray to be used against leaf roller should have 310. S hydrated liixie added for each hn b Mt 7 S M a of lead, or if n M y is bought for this one purpose, basic lead arsenate should be specified.' Inea-x:-; v/u-udGT msecnciaes Contact sprays are, used against a large number of insects and mites, which they destroy by contact or asphyxiation. Almost all the contact sprays of use to the home gardener are proprietary preparations.

Winter spraying oil should contain a guaranteed percentage of oil, have a viscosity of not less than 85 seconds, an iodine value of not more than 30, and a volume of unsaturates of not more than 33 per cent. The volatility should also be low. For woolly aphis and scales this spray should be applied dormant deciduous trees and shrubs a concentration of 3 to 5 per cent, The use of winter oils on evergreen Plants is inadvisable because of its burning effect on the leaves. These recommendations are based on the assumption that the oil content is 100 per cent - Summer oil is used in the home gardBT principally to combat red spider, f2 a Ml ancl . a P ftlces + V 1S „ suitable ; or u ? e spraying O 1 most types of tolluTin§ growing seaso ? and is normally used at concentrations o± °J n 1 21 b 6l ’ cent To soften hard water when oil emulsions are being K d e\^ n &b SOd o%a m et y i0 b 0 e of water tes ‘a"tt Sphate content of 40 per cent. For outside use it is more costly and less efficient as an insecticide than summer oil, but' in confined , spaces such as glasshouses it is excellent for . the control of aphides and .white flies. For outdoor use it is applied at the rate °? \ P ar t 0 per cent, nicotine sulPP ate to 800 parts of water, which es a concentration of 0.05 per cent, When this spray is used alone soft soap should be added at the rate of 31b - per , 100 gallons of water. A 0.04 KndeA n iass concentration is sufficient . under glass. . Garden Hygiene _ ~ , 7 ... Partial sterilisation of soils is a modern practice designed to destroy pests and diseases and indirectly to restore lost fertility. Three simple means of accomplishing this are availaMe to the home gardener. Formalin, at the. rate of 1 pint to 40 gallons of water for each 10 sq. yds. of soil surface, is fairly effective. The surface should be covered with sacks

for a week and then allowed to air O r a fortnight before the ground is use< T Chloropicrin (tear gas) also is satisfactory, but few home gardeners have the injector necessary for the application of the chemical. Low-pressure steam sterilisation can be carried out in the following manner: insert in a copper or other convenient type of boiler a sheet of iron with small perforations, leaving enough clear space for at least a gallon of water in ■ the bottom. Place the soil over the perforated iron and boil the copper for about an hour or until the temperature of the: soil has risen to 200 degrees F. This method is useful in preparing soils for seed raising. The burning of weeds and pruning! from trees and shrubs and the reval of loose bark from trees deprive many pests and diseases of sheltering or breeding places. mntimn’tv f pnnditinne ♦avnnr diseases in the soil can be-broken by “nnlals 0 * buJbf h™d bl * n one P year after year ‘ Diseased plants must be removed and destroyed immediately they are detected if further infection is to be avoided. Careless use of implements often leads to injury of plants, thus making entry points for fungi. Pruning cuts should always be clean, and cuts more than -Jin. in diameter should be sterilised and sealed with liquid coal tar pi an ts should be adeouatelv snared in the bonders otherwise thlv bS! weak snindlv and lls&to ?esi S disease attack. reSlStant t 0 , , Compost heaps are a potential breeding ground for pests and diseases They should be turned regularly and should never have infested material added to them. Such material should be burnt. Stable manure, though useful in many phases of gardening, can be a source of infestation by weed seeds, insects, and fungi.

Garry a elliptica

A. DISTINCTIVE and handsome evergreen shrub, Garrya elliptica has dark green leaves like that of the evergreen oal and from May to September it bears clusters of long, drooping' catkins of greenish-white flowers, sometimes up to 12in. long Because of its larger catkins the male plant is the one in genera! cultivation; the female plant is rarely seen. It should be planted in early autumn or late spring, preferably ! from a pot or when young, as it does not transplant readily ■ when it becomes larger. It grows best in a rather dry, not over rich soil, preferably in a sheltered, sunny position facing nortl or east. Pruning is seldom necessary unless for shape, as the shrub is not fast growing. C. elliptica may be propagated by making 3in. cuttings of the firm, youiTg growth and inserting them in sand in a close frame during January or February. Layering in spring is anothe) means of propagation if suitable growth for this purpose is available. • .

—H. P. THOMAS,

, Vegetable Instructor,

Department of Agriculture, Wanganui.