Growing Cinerarias for Garden and Greenhouse

New Zealand Journal of Agriculture, Volume 81, Issue 5, 15 November 1950, Page 477

Growing Cinerarias for Garden and Greenhouse

CINERARIAS comprise a plant group of great importance and popularity in the home flower garden. Their value is not restricted to the borders, for in a greenhouse they attain excellent proportions, giving brilliant displays of colour during winter. Their culture is not difficult, and

in this month’s article

C. K. Ellis,

Horticulturist, Department of Agriculture, Dunedin, describes how the gardener can obtain the best results from his small packet of cineraria seeds. ACCORDING to their growth and flowering characteristics, cinerarias are divided broadly into three groups. Those known as C. stellata produce, as the name suggests, star-like flowers. The stellata varieties are the tallest, sometimes growing to as high as 3ft. The stems are slender but fairly strong and the flowers are rather widely spaced in the heads. There is a sub-group of the stellata type, known as the cactus group, in which the growth is the same, but the edges of the individual ray florets are rolled back, giving a rather “spiky” appearance. The second group consists of C. grandiflora and its forms. The growth habit of this type is dwarf, with very thick, strong stems. The flowers are large, often as much as 3in. in diameter. Probably the widest colour range is obtained in this group. Between these two groups is one appropriately named C. intermedia, and it is truly intermediate in all respects. Each of these groups has been divided by breeders into innumerable strains and varieties. The most popular and successful of these are listed in almost any flower seedsman’s catalogue. Seed may be sown over several months according to the gardener’s own requirements; whether the bulk of the plants. are required for the borders or for greenhouse work. Cinerarias for the Greenhouse To obtain plants for greenhouse display cineraria seed can be sown at any time from October to February. Sowing a little seed at intervals of a few weeks through this period ensures almost continual displays of brilliant colour from June until November. A very satisfactory soil mixture for this purpose can be prepared by mixing together 2 parts by bulk of loam, 1 part of leaf mould, and 1 part of sharp sand and adding l|oz. of super phosphate and foz. of carbonate of lime to each bushel of the mixture. For home garden purposes a bushel can be taken to be the capacity of a standard apple case. Many gardeners prefer a rather more gritty soil; a further half-part of sharp sand can be added to obtain this condition.

Boxes, pots, or seed pans can be used for the seed sowing. If boxes are used, a layer of coarse, rotted organic matter should be placed in the bottom of each to assist drainage and prevent the soil from falling through' the spaces between the boards. The soil level should be brought to within an inch of the top of the box and tamped down until it is of an even firmness and the surface perfectly level. Pots and pans require adequate drainage material. One large crock is placed over the drainage hole and a few smaller ones around it. On top of these is set about an inch depth of fairly finely broken crocks, and on top of this a gin. layer of organic material, such as spent hops or flax fibre, is placed to prevent the soil from falling among the crocks. The seed soil is then placed in the receptacle and progressively firmed as filling proceeds until the level is about an inch below the rim of the pot or pan and the surface perfectly level. Whatever the receptacle used, the soil content must be thoroughly saturated with water, preferably before the seed is sown for fear of washing it out of the soil by watering afterward. It is better to assume that germination will be good and sow rather thinly and evenly than to assume that germination will be poor and sow thickly, because if germination proves better than expected, the resultant seedlings will have insufficient room for proper development. After the seeds have been distributed over the soil a light “topping” or covering of soil is placed over them. This soil covering may be distributed through a l/14in.-meshed sieve, but if

one of these is not available, one of |in. mesh will suffice provided care is taken that the covering does not become too thick. Capillary action soon draws the water up around the seeds and through the soil cover, so more watering is not necessary for this purpose. The receptacles should be put in a moderately warm place for the seeds to germinate. A glass cover should be provided to prevent excessive moisture loss by evaporation, and a sheet of brown paper prevents the entry of excessively bright light. The seeds do not need a long time to germinate, so a daily watch should be kept for the first sign of the seed leaves, or cotyledons, and when what is thought to be a fair proportion of them have appeared above the soil, first the paper and soon afterward the glass should be removed. The seedlings grow rapidly through the seed-leaf stage and soon produce the first of their true leaves. Therefore the plants should be pricked out as soon as possible after the full development of the seed-leaf stage, or at least not later than when each plant has only two true leaves. Pricking out later than this causes too much root damage, recovery from which is often slow. The soil mixture used for seed sowing is excellent for pricking out, and the seedlings are pricked out 2in. apart in boxes prepared in the same way as for seed sowing. During this operation, however, the boxes are not watered before the plants are pricked out but afterward, with a fine spray. This moistens the whole plants and assists the roots to settle into the soil. When the leaves of the plants touch each other- in the boxes it is time to

pot them up into 3 or 4in. pots. A good potting mixture is one consisting of 7- parts by bulk of loam, 3 parts of peat or leaf mould, and 2 parts of sharp sand, with IJoz. of dried blood, IJoz. of superphosphate, ioz. of muriate of potash, and joz. of carbonate of lime added to each bushel of the mixture. The pots should be well crocked and well filled with soil, for the small plants soon grow through them. The soil level should be no more than gin. from the rim of the pot. After a couple of days in the greenhouse to allow the plants to recover from the potting they should be placed out in a cold frame where they have a better chance of remaining cool during summer. As soon as the small pots become filled with roots the plants should be potted on to 6 or 7in. . pots according to their vigour. The same soil mixture as for the original potting should be used, and after being potted on the plants should be returned to the cold frame and allowed to remain there until colder weather approaches. At the first sign of frost the plants should be taken into the greenhouse and given adequate space for full development. Some provision should be made for shading them from strong, direct sunlight and the temperature of the greenhouse should be kept as low as possible without its being reduced to less than 40 degrees F. by night. If the plants are required for display at an early date, 50 to 55 degrees is the best temperature range in which to grow them.

All that is required of the gardener from then on is attention to watering and picking the plants over occasionally to remove dead ,or unhealthy leaves. Especially when the plants have been grown rapidly, it may be found necessary to feed them as they approach the flowering stage, and weak liquid manure is satisfactory for the purpose. It can be prepared by suspending a bag containing a few pounds of animal manure in a drum of water.. This “feed” should be used only when the plants obviously need supplementary food, such as when the roots are growing vigorously through the drainage hole at the bottom of the pot, or when the leaves are yellowing slightly : as a result of starvation. Overfeeding does more harm than good. Before the liquid manure is applied it is wise to water the plants thoroughly, as damage is often caused by applying the “feed” to a dry soil. Cinerarias for the Borders The early procedure in raising cinerarias for the borders is the same as that in raising them for the greenhouse. The seeds are sown during October, November, or December and pricked out in the same manner. However, when the leaves of the plants touch each other the plants are not potted up. The boxes are placed in a cold frame or some other sheltered spot for a brief period and the plants gradually hardened off until they are able to stand normal atmospheric conditions. At any time after

they have reached this stage they may be planted out in the borders, preferably in a moderately frost-free position. Enemies of Cinerarias The most common enemy of cinerarias in New Zealand is the “woollybear” caterpillar, the larva of the magpie moth. This pest is a voracious feeder and has a partiality for such weeds as groundsel and ragwort; in fact, it was introduced into the country some years ago with the aim of destroying ragwort. Complete control of such weeds greatly increases the chance of freedom from the depredations of the caterpillar. A sprinkling of derris dust over the plants at intervals keeps the larvae at bay. Greenflies (aphides) do great injury to cinerarias by puncturing cells of the stems and leaves and sucking the sap. Spraying with nicotine sulphate at the rate of 1 part in 800 of water (i fl. oz. to 2 gallons of water) gives satisfactory' control if repeated at 10day intervals until all trace of the pest has disappeared. To each 2 gallons of this mixture should be added loz. of soft soap or 3 fl. oz. of summer spraying oil. The leaf-miner maggot also attacks cinerarias. The fly lays its eggs on the leaf and when they hatch the maggots burrow into the leaf and devour the tissue between the upper and lower epidermes. The best means of control are the eradication of weeds such as groundsel and thistles, which it also , attacks, and crushing the maggots inside the leaves whenever they or their tracks are noticed. The maggots are about Jin. long. Dusting leaves with derris tends to prevent the flies from laying their eggs. Garden Work for December Annuals from late sowings should be finally... thinned. The hoe cannot be put to.. much good use in flower borders, so most of the weeding must be done by hand. Only the tallest and most vigorous types of annuals should need staking. Only by continual removal of all dead flowers and developing seed pods can a continuous display of flowers from annuals be guaranteed. Bearded irises have horizontal fleshy stems or rhizomes, which develop along the surface of the soil and soon overcrowd each other. For good displays and healthy plants these irises should be lifted and divided every 2 or 3 years. It is possible to lift and divide them immediately after they have ceased flowering; in fact, under New Zealand conditions, this appears to be the best time for the operation. Bearded irises thrive in a rich, welldrained soil and appreciate an annual dressing of 2oz. of superphosphate and 2oz. of carbonate of lime to each square yard of bed.

Begonias of the tuberous-rooted type growing in pots should be coming into flower and, if necessary, they should be fed with weak liquid manure. Feeding after the main flowering period has been reached tends to induce weak, useless growth. Laterals (unwanted side shoots) can still be removed to be used as cuttings. The small side flowers (females) should be removed, as they are of little value

and detract from the beauty of the main or terminal flower. Borders should be overhauled during December, marguerites, wallflowers, and other spring-flowering plants which have- passed their best being either cut back severely or pulled out. The gaps left : can be planted up with late-raised bedding plants such as marigolds. Bulbs which flower in spring, such as daffodils, hyacinths, and tulips, may be lifted as soon as the leaves have turned brown and withered. They should never be lifted before this, because the bulbs depend on the food withdrawn from the leaves for their well-being next season. When the bulbs are lifted the soil should be shaken from them and the foliage left on if it does not fall off readily. They should be placed in a single layer in wooden trays and be put in an airy shed to dry off. If they are stored in heaps, they sweat and deteriorate, and if left outside exposed to the sun, they are also damaged. This applies particularly to tulips, the development of which is greatly hampered by exposure of the bulbs to bright sunlight. Dead foliage and loose scales can be removed as soon as the bulbs are quite dry, but twin or triple bulbs should not be pulled apart at this stage, because injury to the basal plate and entry of fungus may result. Rotten bulbs or ones soft at the neck should be burnt immediately, for they are likely to be infected with the pest known as bulb mite. Bulbous irises will start to die down in December, and these too may be lifted and stored as soon as the foliage has withered. These bulbs will be replanted in early autumn, but bulblets may be removed and sown in drills almost straight

away; in 2 to 3 seasons they will produce flowers.

Carnations should be layered as soon as the growths are large enough to be handled easily. About sin. back from the tips the stems should be split up the centre with a sharp knife and pegged down into the soil with a fairly shallow covering over them. In frost-free ~ districts the perpetualflowering types are greatly preferable to the border varieties, as they flower over a much longer period. Chrysanthemums should be staked as soon as they have grown tall enough to need support. Delaying this job is foolish, for winds can take heavy toll of the best stems. A stake should be driven in a little behind each stool and the main stem tied to it. A loose loop of raffia right round the plant and stake is of assistance in very windy localities. The stake should be about as tall .as the height to which the flower stems are likely to grow. Dahlias require a lot of water during their growing season. If the soil becomes dry, it should be given a thorough soaking, . and a few hours later it should be gone over with a hoe to prevent caking. Staking should be continued; further ties will be necessary on stakes put in during November.

Fuchsias will be growing strongly during December and should be watered thoroughly if necessary. They appreciate a light dressing of equal parts of superphosphate and sulphate of ammonia watered in at the rate of |oz. per gallon of water per square yard.

Herbaceous plants such as lupins, delphiniums, and doronicums should now receive attention in the earlier districts. Faded flowers and flower spikes should be cut off and the plants generally tidied up. When flowering has finished, cutting the stems back to the ground and giving a generous mulch of good compost around the plants often produces a further batch of shoots which will flower during late autumn; the second shoots should be thinned out to two or three per plant. Pinks should be replanted every 2 or 3 years, because old plants produce few flowers and look untidy. Pinks can be propagated from December to February by “pipings”, which are pieces 2 to 3in. long pulled from the centres of the new shoots. These should be inserted in sand in a cold frame or in boxes with a sheet of glass over them. A sheet of newspaper should be placed over the frame or box to exclude intense sunlight. In 3 to 4 weeks the pipings will have rooted, and soon afterward they may be planted out to their flowering' positions. Pruning of ornamental brooms should be done as soon as they have finished flowering. Cutting into old wood is likely to be fatal. The best plan is to shorten back to within an inch or two of its base each shoot that has flowered; new shoots will grow from the stub that is left. Earlyflowering heaths and deutzias should also be pruned back hard immediately after they have flowered. Roses of the climbing' and rambling types should have their new growths tied in before they are long enough to sway about and become damaged. Roses of all types can be budded as soon as the bark lifts readily on the stocks. Seed of quite a number of herbaceous perennials which are cheaply and easily raised in the home garden may be sown during December. Among these are Russell lupins, aubrietias, anchusas, thalictrums, heucheras, and Alyssum saxatile. The seeds should be sown in boxes or in small open

beds and the plants set out in the borders in autumn. Sweet peas will be in full bloom in December, and every few days all spent flowers and developing seed pods should be removed to keep the plants blooming well. Removal of a few of the side shoots during the growing period keeps the plants open and gives adequate room for the development of long flower stalks. Seasonal Pests Aphis (greenfly) will again be troublesome during December on a very wide range of host plants. Nicotine sulphate sprays should be used at regular intervals to control it.

Chrysanthemum eelworm attack will now be showing its effect on the lower leaves of the plants. These particoloured, shrivelled, or dead leaves should be removed and. burnt. Regular spraying with nicotine sulphate assists in preventing further migration of the eelworms. Narcissus flies of the large type are a common and important pest of many flowering bulbs. They are stout, hairy insects, usually marked with red or orange bands. They lay their eggs near the bases of the leaves of bulbous plants toward the end of the bulbs’ growing season. When bulbs are near the surface the flies may crawl down and lay their eggs directly on the bulbs. In either case, after the eggs have hatched, the larvae eat their way into the bulbs, which, even if they are not killed, are prevented from flowering in the following season. Affected bulbs are shrunken and soft and usually have a corky basal plate. The larvae, which are .maggots, may be seen if the bulb is broken open or cut through the middle with a knife. The larvae remain inside the bulb right through the dormant season, and this fact has a great bearing on the distribution of the pest. As the larvae are completely enclosed within the bulb, heat treatment is the only measure which is completely effective against them. It consists of immersing the bulbs for 2 hours in water which is maintained at 110 degrees F. Care should be taken not to exceed that temperature or the bulbs may be killed. This treatment should be given all new stocks of bulbs as a precaution against introducing the pest into a clean garden. Thorough cultivation of the soil between the bulbs as soon as the foliage begins to die down, and after it has been removed if the bulbs are not lifted, fills all holes left by dying down of leaves and makes reaching the bulbs much more difficult for the flies and larvae.

Ericas for Winter Flowers

TJOPULAR shrubs of a very large and important genus consisting of several hundred species and varieties are Erica melanthera (left) and E. pyramidalis (right). Like i most ericas, these species are very free flowering and are worth a place in all plantings of shrubs, as they flower from mid-winter when other blooms are scarce. They grow most freely in a lime-free, peaty soil, rather light and well drained— to that which suits rhododendrons, azaleas, and kalmias. ' These species appear to grow well without any special care and make a brilliant show when covered with bloom. If pruning is necessary to keep them bushy, it should be done immediately after the plants have flowered. Selected varieties must be reproduced by cuttings, which must be firm, young side shoots -g- to 1 in. long, preferably taken with a heel during January, February, or March, and inserted in a close frame in a cool greenhouse. They are then transplanted to prepared beds the following spring. The potting medium recommended for raising cuttings is clean, coarse sand, plus peat that has previously grown heather if available, and this should be' well watered and rammed firm.

—H. P. THOMAS,

Vegetable Instructor!

Department of Agriculture, Wanganui.