Flower Borders Need Plant Food

New Zealand Journal of Agriculture, Volume 74, Issue 3, 15 March 1947, Page 325

Flower Borders Need Plant Food

IN autumn it is usual to take stock of the flower garden and decide whether the season has been satisfactory. The manuring of borders is often overlooked, and a poor display during the summer may have been caused by neglect to provide flowering plants with the food they need. The manuring of flower borders is discussed in this article by J. P. Hudson, Horticulturist, Wellington.

UVERY pound of vegetables removed from the kitchen garden contains some plant food taken from the soil, and few gardeners expect to grow good crops of vegetables without returning plant foods to the soil in an annual dressing of animal manure or fertiliser, or both. Every bunch of flowers cut from the border, every dead flower head or seed pod picked off flowering plants, and every branch pruned off trees and shrubs has also removed some plant food from the soil.

Flowers Need Plant Foods. Yet it does not seem to occur to many gardeners that the flower borders deserve an annual feeding and - will pay just as handsome a dividend for it as the vegetable garden. The question is often asked: “How much manure should be given the flower border, and what sort of manure is required?” Unfortunately, there is little reliable evidence on which to base a recommendation, and . hardly any properly-recorded experimental data are available on the question. The plain fact is that little is known about the manuring of flower crops, though a confusing mass of information —much of it conflicting—is published in gardening books and articles.

The Main Plant Foods

It is known, however, that it is easy to over-manure flower beds, especially when applying nitrogenous fertilisers, as too much nitrogen tends to cause plants to produce an abundance of foliage at the expense of flowers. The use of quick-acting nitrogenous fertilisers, such as sulphate of ammonia and nitrate of soda, is especially likely to cause flowering plants co produce too much leafage. For that reason nitrogen in some organic, slowacting form is usually to be preferred for flower production.

Phosphorus assists plants to develop an extensive root system, and is valuable in helping bedding plants to recover from the shock of being transplanted and in encouraging flowering plants to make a deep and extensive rooting system capable of collecting as much moisture as possible when the soil tends to dry out in the summer.. As many soils in New Zealand are naturally deficient in phosphorus, -it is safe, and indeed wise, to apply a dressing of phosphatic manure to the flower border at least once a year. Potash is always regarded as important for flower production and the general health of the plant, but is present in adequate quantity in many soils in the Dominion. In the absence of more accurate knowledge of the potash requirements of individual flowers, the use of this manure on flower beds can be regarded as a general insurance rather than as likely to lead to any spectacular improvement in the border. The minor elements, of which much is heard now in connection with farm and market garden crops, no doubt

play an equally important part in the health of flowering plants. However, no experimental work has been done on the effect of the minor elements on flower production, and no recommendations can be made. A Balanced Annual Dressing So far as the rather sketchy knowledge available goes, the following mixture appears to provide the plant foods which flower crops require in the form and proportions in which they are likely to be most valuable: , Blood and bone: 3 parts by weight. Superphosphate: 2 parts. Muriate of potash: 1 part. The mixture, used at the rate of 2oz. a square yard, should be applied to the whole area of the flower garden once a year, preferably when the ground is dug in early spring, or, in the case-of shrubberies and herbaceous or mixed borders, as a topdressing when they are first cultivated after the winter. Liming the Flower Border Some plants, such as daphne, rhododendrons, and most heathers, are said to “hate” lime, as their leaves will go yellow and the plants may even die if planted in a soil which contains free lime. It would obviously be unwise to apply lime to a border which contained these plants unless it was very acid in the ' first place. On the other hand, many flowering plants do best if the soil is about neutral, while a few thrive in soil which is strongly alkaline. The whole subject of liming the flower borders will be dealt with in detail in a future issue. Meanwhile

it is strongly recommended that lime should be used only sparingly, if at all, on the flower border. Humus is Essential Plants can he expected to grow " properly only if they can draw on a supply of the foods described. In addition, however, the physical condition of the soil is most important. A soil lacking in humus tends to be sticky in wet weather, cakes badly after rain, cracks in a drought, and soon dries out in dry weather. These defects can be made good to a large extent by adding humus to the soil, and it should be a routine measure to apply a dressing of compost, wellrotted animal manure, leaf mould, or other form of humus every year. This organic material may be worked into the soil whenever it is dry, but on beds where semi-permanent herbaceous plants or shrubs make digging impossible it is best applied as a topdressing. For topdressing the material should be broken up, passed through a coarse riddle, and then spread evenly over the surface between the plants in . a layer up to Jin. thick in late spring or early summer after the soil has warmed up.

GARDEN WORK FOR A . ITS Ik . . AU I UMN

Beds of hardy annuals, bedding plants, and other seasonal subjects now past their best should be cleared, dug over, manured if necessary, and trodden firm again ready ■ for replanting with spring flowers. Good displays of flowers cannot be expected year after year unless the soil is kept fertile by replacing the food which is used up in producing the flowers, and also by adding some form of humus to keep the soil in a satisfactory physical condition. Dahlias may be left in the ground all through the winter in favoured, frost-free districts and treated as ordinary herbaceous perennials. Elsewhere, or if the stock is to be increased, the roots should be lifted as soon as the leaves and flowers shrivel, taking care not to injure the tubers. Cut the old flower stems down to 6in., tie a label to the stems of named varieties, and put the roots in an airy place to dry off. When they are dry store them in a cool but frost-free place. Evergreen hedges should be trimmed at once for the last time this season, if that has not already been done. The clippings of all hedges, including coniferous species, are too valuable to burn and should all be put on the

compost heap. If there is a high proportion of dry, twiggy material, it should be sprinkled lightly with sulphate of ammonia and covered with a layer of softer refuse, such as lawn mowings, to ensure that it rots down.

Gladioli should be lifted as the leaves turn yellow and before the plants have died down completely .to ensure that the bulblets are still -firmly attached to the main corm. Spread the plants out to dry in an airy place until the stem is brown and the leaves crisp, then cut off the stems lin. above the corms and put the corms away in well - ventilated, properly - labelled boxes until the time for examining and cleaning them (which will be dealt with later).

Hellebores of various species are of little value as ornamental plants, but are useful for cutting, as their unusual flowers grow during the winter. Plants should be put in a shaded place, where they will flower for years after becoming established, but should not be moved unless it is essential, as they resent being disturbed and often take some years to recover. Heavy rain is apt to splash the petals with soil, especially in the case of the species with short flower stalks, which are worth covering with a glass light or cloche at this time of the year, both to ensure clean, unspotted flowers and to encourage longer stems.

Herbaceous plants have now finished or nearly finished flowering. As they go out of bloom and the foliage turns yellow, sever the ties, remove the stakes, and cut each stem down to about 6in. above the ground. The old stalks are all worth putting on the compost heap to rot. If it is proposed to remake the herbaceous border this winter, or to divide some of the plants, care should be taken to label the plants when the flower stems, are cut down, as some of them may be hard to recognise later when only the cut stumps remain. At the same time coloured tags should be tied on to the stumps to indicate which, clumps are to be thrown out and which are to be increased and replanted.

Lily of the valley beds which have become overcrowded are best replanted at this time of the year, when the leaves have turned yellow. The old plants should be lifted carefully and the bed thoroughly and deeply dug, at the same time working a liberal dressing of old animal manure or compost into the lower' levels of the soil. Before replanting the bed tread it thoroughly, as lilies of the valley thrive best in a firm soil. From , the plants dug out select the best crowns for replanting. Each consists of a large bud to which should be attached a bunch of long, strong roots. Plant the crowns 3 to 4in. apart, using a trowel to make holes deep enough to

take the roots without doubling them up and with the crowns just below the surface of the soil, which should be refirmed after' planting. Lilies of the valley can be expected to succeed only in a fairly deep, moist soil in shady positions. A few • spare crowns can be potted and grown in the house to provide fragrance in the early spring. ( Planting of the following should be completed as soon ■as possible before the cold weather makes their establishment more difficult: Hollyhocks, Canterbury bells, wallflowers, pansies, violas, polyanthus, Iceland poppies, stocks, ranunculuses, and anemones. Shrubs which can be propagated from cuttings of new growth, 8 to lOin. long, taken at this time of the year, include Lonicera nitida, privet, laurel, Escallonia spp., and many others. The leaves should be removed from the bottom half of a cutting, which should then be cut off just below the' place where the lowest leaf was attached and inserted firmly into the soil sloping at an angle of 45 degrees away from the prevailing wind. It is essential to make the cuttings firm, as the slightest rocking by the wind will prevent any roots from forming. Rooting hormones have proved effective in accelerating root formation on many of this class of cuttings, though it is only fair to say that most of them will root in any case if correctly trimmed and inserted.

Sweet peas to flower next year can still be sown out of doors in all but the coldest districts. Plants from this autumn sowing are hardy enough to stand . the winter cold, and will produce much earlier flowers next season than those sown in the spring. Walnuts will now be ripening. Grass growing around trees should be cut short and raked off and the ground generally . tidied up to make collecting the nuts easier. When nuts start to fall the branches should be shaken vigorously with a long pole to make as many fall as possible. They should be picked up, husked if necessary, and dried by spreading them in a thin layer on a shed floor. Nuts should not be left lying on the ground longer than necessary, as dew and rain can cause the shells to discolour. The over-vigorous beating of trees at harvest time, causing much damage to young shoots, has nothing to recommend it and leads only to increased disease. The old saying, “A woman, a dog, and a walnut tree, the more they are beat, the better they be,” is misleading least as far as the walnut tree is concerned!

Reminders About Garden Troubles

Lily diseases. The two common diseases of lilies cause much avoidable loss of lily plants every year in New Zealand gardens. Virus diseases: Many types of garden lily are attacked by virus diseases, of which there are several, including

one which is closely allied to the “breaking” virus of tulips and which occurs on Lilium tigrinum and L. longiflorum. Affected lilies can be recognised by the abnormal appearance of the leaves, which are flecked or streaked with yellow; stunted plants and misshapen, ’ twisted flowers which fail to open properly are also signs that- the plant is infected with virus. So far as is known, the diseases are spread mainly by insects and especially greenflies. Plants attacked by virus cannot recover but should be dug out and burned as soon as the symptoms are seen. To leave infected plants in the bed is only asking for trouble, as they are likely to serve as a centre from which infection can spread to healthy lilies. It is also worth while, especially in valuable collections, to apply a nicotine spray to all the lilies every 10-14 days throughout the season to keep down the aphis population. Occasional aphides, coming in from elsewhere, may still bring fresh infection, but routine spraying does much to prevent its wholesale spread. The . lily virus diseases are not transmitted through their seeds. One way, therefore, of obtaining healthy plants of species (but not of hybrids) is to grow them from seed. Virus diseases are transmitted to the new plants if lilies are propagated by bulb scales or bulbils. Botrytis disease is caused by a fungus (.Botrytis sp.) and results in

brown spots on the leaves, which later die and shrivel up. In severe attacks the flowers and even main stem are also killed by the fungus, leading to the death of the whole plant. The disease, which is spread from plant to plant mainly by the wind, is always most severe in wet seasons. The fungus may live from one year to the next in dead leaves or stems, or even in the soil, but by far the most important source of infection is in diseased leaves of Lilium candidum, which retains a rosette of foliage through the winter and thus serves as a centre from which the disease' can attack other species in the spring. A reasonable measure of control of botrytis disease can be obtained by: 1. . Cutting down to the ground and burning any plant seen to be attacked; 2. Pulling off and burning the basal rosette of leaves from L. candidum in midwinter (this does not harm the bulb); 3. Burning dead lily stems and foliage when they die down after flowering; 4. If the slightest signs of attack are seen, applying a copper fungicide spray at once to protect ■ the remaining lily foliage. It is a bad practice to leave a few inches of the old flowering stem to mark the place of the bulbs. When the leaves go brown the stems should be cut to below ground level or pulled right out. A stick can then be inserted to mark the site.