Lown Management is a Large Part of the Flower Gardener’s Tasks

New Zealand Journal of Agriculture, Volume 81, Issue 4, 16 October 1950, Page 383

Lown Management is a Large Part of the Flower Gardener’s Tasks

IF the average home gardener analysed his working time in his garden, he would find that a remarkably large proportion of it was spent on his lawns. Probably in most cases sufficient time is given to work on the lawns, but in many instances insufficient thought is given to them. In this month’s article for the flower gardener C. K. Ellis, Horticulturist, Department of Agriculture, Dimedin, discusses the more important aspects of good and efficient lawn management. LAWNS, like all other parts of the garden, usually benefit from regular applications of fertiliser. Such applications should be made four times each year, in spring, in midsummer, during early autumn, and in midwinter. The fertiliser mixture most suitable for general recommendation in New Zealand consists of 3 parts of sulphate of ammonia, 1 part of superphosphate, and 1 part of stdphate of iron. This mixture should be distributed evenly at the rate of loz. per square yard. Readily available nitrogen in small amounts is most desirable during the growing season, for it increases the vigour .of the grasses and improves their colour. Such nitrogen is supplied by the sulphate of ammonia, but the effects are only temporary, so that to obtain the maximum benefit from the fertiliser the applications must be regular. If the mixture is applied dry, the grass should also be dry at the time or burning will result. The fertiliser should be watered in thoroughly immediately after application. Applying the fertiliser in liquid form is preferable, loz. of the mixture to 1 gallon of water being used for each square yard of the lawn. This method usually obviates the risk of burning the grass. Topdressing Lawns Several purposes are served by topdressing a lawn: Slight depressions are levelled, a light mulch is provided for the grass roots, and a certain amount of mineral plant food is supplied. Several light dressings at fairly frequent intervals give vastly better results than heavy ones applied at long intervals. The depth of topdressing material should never exceed Jin., the ideal being about Jin., and the work should be done during either spring or autumn. The material should be spread evenly over the turf and be carefully raked into the grass or worked down into the low spots with a rake or with a board attached to a handle. Soil passed through a Jin. sieve is most suitable as topdressing material. Dressings of pure materials such as clay or sand are most undesirable, for they bring about a layered condition which interferes with the movement of water in the soil.

Lawn-mowing Technique A lawn is mown chiefly to improve its appearance; mowing is not, as many people believe, beneficial to the grasses. The bulk of the fpod of grass plants is produced in the leaves by the action of sunlight in a process known as photosynthesis. Therefore the more leaf a plant has the more food is available for growth, the greater will be the root system, and the stronger will be the plant. The strength and extent of root growth are proportional to top growth. A blunt mower bruises and crushes the tons of grass blades instead of cutting them cleanly and is usually responsible for the brownish colour of a lawn a few days after it has been mown. The mower must be sharp so that the grass blades are cut cleanly without bruising or crushing and no pull is exerted on the roots of the plants. It pays to buy a good mower and to keep it in good condition by cleaning it regularly and oiling it frequently with high-grade light machine oil. Newly established lawns should be mown when the grass is 1| to 2Jin. high. Established lawns should seldom be cut much lower than lin. from the soil; quite often lawns are damaged severely through being cut too closely. On large areas of lawn which are reasonably weed free grass ljin. long does not impair their attractiveness. More than about an inch of grass should never be cut off with the mower at one time. In the warmer districts that probably means mowing every few days. If grass is allowed to grow long before being cut, the lower parts that are left will be bleached and rather ugly and many

weeks may pass before such grass recovers and regains its healthy green appearance. On the other hand, continuous close cutting may produce such symptoms as thinning of the turf, lack of resistance to drought, and invasion by weeds. Clbse cutting also inhibits the healthy development of the root system, necessitating more frequent applications of fertilisers and greater attention to watering. Shaded places in a lawn where grass growth is weak should not be mown as frequently as other areas. Light mowing only a few times a season should suffice, normal mowing being likely to kill the grasses in such situations. Lawn Clippings may be Left The clippings from the first mowing of a newly seeded lawn should be left on the ground. They form a good mulch, keeping the soil moist and the young grass roots protected. That is also true with established lawns, but if the grass is left to grow for some time before each mowing, a large amount of clippings will be left each time. If left to lie, these clippings turn brown and look unsightly, and if the clippings are removed, the basal parts of the plants are likely to be injured by the sudden exposure to sunlight. Therefore a lawn should be mown frequently enough to prevent the production of long blades of grass, thus relieving the gardener of the necessity of removing the clippings. Leaving the clippings on the lawn is quite safe if the lawn is reasonably free from weeds. If a lawn is heavily infested with weeds, a grass-catcher should be used, as to some extent it checks the spread of and reinfestation by weeds. Recent research work in New Zealand has shown that removing the clippings at least at alternate mowings may be beneficial.

Value of Rolling

Much argument centres at present around the subject of rolling lawns. Many reasons for rolling have been put forward from time to time, the chief ones being to firm the soil about the grass roots and to encourage capillary action in bringing up water supplies from the soil below the plant roots. In the colder inland parts of New Zealand where frosts are frequent and severe during winter, rolling for the first reason would seem fully justified and is recommended during early spring. Rolling does not, as many people believe, level uneven surfaces, but simply brings about uneven soil conditions which ultimately result in a patchy turf. For levelling out depressions there is no substitute for topdressing. If a roller is used, its weight need not be more than 1501 b. Under most conditions a roller heavier than this causes the surface to become hard and almost impervious to water. Aeration of Turf On well-constructed lawns it is not often necessary to assist aeration of the turf by artificial means. However, the soil of many lawns is hard and impervious and the turf is failing to maintain a healthy condition. In such cases deep spiking with a garden fork may do much to improve the situation. The tines of the fork are pushed as far into the ground as they will go, wriggled a little to make the holes wider, and withdrawn. This allows rapid penetration of air and water, as well as allowing fertilisers to reach the grass roots more quickly. A wide range of spiking and coring machines, is manufactured for use in the aeration and general improvement of larger areas of grass. Watering Lawns Watering is probably the most important factor in maintaining a good lawn. Without adequate water lawn grasses will not thrive. Admittedly, established grasses do not seem to be permanently injured by periods of drought, but during those periods they do look unsightly, and the only way to have a good green lawn throughout the year is to water .it regularly during dry spells. When watering becomes necessary it is essential that it be done thoroughly. All too often the gardener plays a hose over the lawn and imagines that in 5 minutes he has done some good, whereas in fact he need not do this very often to cause quite a measurable degree of harm. Light watering moistens only, the uppermost soil region- ahd/' because of the presence of water, the grass roots tend to develop there. and are not encouraged to penetrate more deeply. The condition gradually deteriorates until all the roots are in the uppermost - inch or so of soil, and the turf loses almost entirely. its resistance to drought and suffers at the slightest dry spell. A lawn which is being watered should always receive , enough water to wet the soil to a depth of at least 6in. In this way the grass roots are kept well down in the soil and water need not be applied so frequently.

The time of day is not important in watering lawns; in early morning or evening evaporation rates may not be as high as at other times, but this is so small a factor that it may be disregarded. Watering a lawn in full sun is not harmful. A good variety of water-sprinkling equipment is available to the home gardener at very reasonable cost, and some equipment of this nature cannot be regarded as anything but a good investment. Insect Pests of Lawns The grass-grub (Odontria zealandica) is probably the most harmful of all insect pests which attack lawn grasses in New Zealand. The adult form of the grass-grub is the wellknown brown beetle, which is about gin. long and brown, with darker margins on the wing cases. It has only a few hairs, these being along the sides of the body. The beetles are nocturnal in habit and feed on the foliage of a very wide variety of plants, including many ornamental species. There is normally only a single brood each year, the adults being found usually during November, December, and January. Normally the the female lays eggs at the bases of grass and other plants, and these hatch

to grubs in 9 to 11 days, burrow below the surface, and begin feeding on the roots of many plants. In the depth of winter they cease feeding, burrow down a few more inches, and build a smooth-walled cell in which they lie until about August. Then they ascend and feed again, growing to full size, and finally, after a pupation period, emerge as beetles. Control is difficult, especially of the grubs. D.D.T. (lib. of 50 per cent, wettable D.D.T. per 100 gallons of water) is a useful spray for foliage to minimise the damage done by beetles and to reduce their number. Arsenate of lead powder, at the rate of 21b. to 400 sq. ft., applied with a spreader of sand, is useful to proof the soil against grubs when a new lawn is being laid down. On established lawns arsenate of lead powder applied broadcast at the rate of 51b. to 1000 sq. ft. proofs the grasses against infestation for about 3 years. Porina “grubs” or subterranean caterpillars are the larval forms of the large native nocturnal moth illustrated on this page. These moths are active during spring and summer. The caterpillars, which are voracious feeders, emerge by night and feed on the surface. The caterpillars are greyblack with black heads. They may be 2| to 3in. long when fully grown, and they burrow holes in the turf from which they emerge at nightfall to feed on the grass foliage. Extreme damage caused by this pest is not usually apparent until autumn or early winter, when the grasses may die as the direct result of almost compfete defoliation. In bad cases the soil surface appears to be perforated with holes about the diameter of a pencil. Poison baits have been found most effective in controlling this pest; 21b. of wheat bran mixed thoroughly with 2oz. of arsenate of lead powder or loz. of Paris green, moistened slightly, makes sufficient to broadcast over 1500 sq. ft. The application should be made on a fine, warm evening. Both arsenate of lead and Paris green are extremely poisonous. substances and the greatest care should be exercised in using them, especially • where there are children or pets. The baits are best applied during January, and repeated in February if the attack is serious. An alternative to the laying of baits is the application of “Gammexane” (benzene hexachloride) in powder

form at 2oz. per square yard. These larvae, like grass-grubs, are largely inactive during winter and begin to emerge in spring as adults. . Control of Weeds in Lawns Probably the most widely used of the chemical treatments for lawn weeds in past years has been a mixture of sulphate of iron and sulphate of ammonia. Sulphate of ammonia in itself used regularly in small quantities deters many weeds, but the addition of a third of its weight of sulphate of iron assists its action on weeds. This combination of chemicals should be used at the rate of loz. per square yard and sprinkled over the grass in the early morning while the dew still lies and when there are prospects of a good day to follow. Should hot, dry weather follow an application, burning of the lawn may result. In such a case no further application should be made until the grasses are quite green . again. Up to 6 applications at 10-day intervals may be needed to clean up a very weedy lawn. Pearlwort, chickweed, and pennyroyal are comparatively resistant to this mixture, but catsear, .plantains, dandelions, and clovers can be eradicated by its use. A pinch of the mixture placed on the crown of a large rosette weed will produce the desired effect. The selective weedkiller 2, 4-D (dichlorophenoxyacetic acid) is a hormone or plant-growth regulating compound which, when applied at a certain concentration, destroys a wide variety of broad-leaved weeds but does not injure the grasses. The fact that it kills not only the leaves and stems but also the roots makes it more efficient than most weedkillers in that it prevents regeneration. A few weeds are resistant to 2, 4-D, but it checks their multiplication by preventing them from setting seed.

The chemical is reasonably cheap and is safe and easy to apply. Many proprietary preparations of 2, 4-D are available. Concentrations may vary, so they should be applied strictly according to the instructions of the manufacturer. The concentrations are usually 1000 to 1500 parts to a million of water, and sprays at this concentration are applied at 1 gallon to every 200 sq. ft. to give effective control of most weeds.

A fine spray that completely covers the lawn and wets weed leaves can be obtained with a knapsacktype sprayer. Calm conditions are desirable, for wind-blown spray may do considerable damage to ornamental plants in nearby borders and beds. A few days after being sprayed the leaves of the weeds begin to twist and curl in a peculiar manner and death soon follows. Killing is most rapid and effective when the weeds are growing actively or when they are soft and succulent.

A sprayer used for applying 2, 4-D should not be used for any other purpose until the residue in the equipment is removed completely, otherwise severe plant damage will result.

To remove the residue fill the tank with hot water, rinse it thoroughly, pump some through the system, and drain it. Fill the tank almost completely again with hot water and add 1 part per 100 of household ammonia. Agitate the whole equipment violently and pump the solution through the entire system. Drain the

Lire; tunic OJDVUIII. X7IQIU me pump and rinse it with hot water. The treatment with ammonia is now repeated, but instead of the solution being- drained off it is allowed to stand in the equipment for 24 hours. After this period the system is drained and rinsed thoroughly . with fresh water. Garden Work for November Annuals can still be sown if the soil is not too dry, but late sowings often give uneven germination and poor growth. For late flowerings, orange and yellow calendulas should now be sown in , boxes and the seedlings pricked out into other boxes as soon as they can be handled. They may be planted out to the borders early in the new year. Though calendulas are moderately resistant to drought conditions, they should be watered thoroughly before they are planted out. Bedding plants - such as petunias, marigolds, salvias, asters, stocks, phlox, and zinnias can still be planted out this month. If the soil is dry, it should be watered thoroughly the day before planting takes place, and in such a case it is unwise to firm the soil too much when planting for fear that it should set hard. Bulb foliage should not be cut off until it turns completely brown. In this state it is quite useful for the compost heap. In early districts tulips and daffodils may be dug up and put in an airy shed to dry off. Tulip bulbs should never be left in sunlight, as high temperatures may restrict their proper development. Tulips should be lifted every year unless they are planted very deeply. Daffodils need be lifted only every second or third year.

Chrysanthemum planting should be concluded, even in the latest districts, by setting out well-rooted plants of a variety suitable for border display. Tne soil should be well dug and enriched with compost or manure before plants are set out. Dahlias may well be planted out in cold districts where early planting is unwise, and in milder districts late pot tubers may be planted during November to give colourful display alter tne main crop has passed. Earlier plantings in mild districts will now be growing strongly and, if necessary, snould be thinned by the removal of a number of the young shoots. These may be cut with a sharp knife, but pulling them away gently with the fingers may be found a better method in that it removes also the lower buds on tne stems and prevents further growth from these ,buds. At later stages staking will be necessary, and eacn staKe should be almost as long as the flowering stem, so that the flower when produced is only slightly above the top of the stake. The stems should be tied to the stakes with twine so they are unable to twist about in the wind and break off. Gladioli, which will be growing strongly in early districts, should be staked unless they are very well sheltered.. Each stake should be pushed into the ground 2 or 3in. behind the plant and each spike tied only loosely. Very firm tying may bruise the stems and restrict their growth. Hedges should be given their first clip of the season as soon as early growth makes them appear untidy. Provided the clippings are clean, they are a useful addition to the compost heap.

Mulching of camellias, hydrangeas, rhododendrons, and azaleas during November with well-rotted compost, sawdust, or leaf mould helps to conserve moisture and maintain suitable soil conditions. Should the soil be dry, it should be watered thoroughly before the mulch is given.

Pot-grown fuchsias and heliotropes should be planted into the massed flower border to add interest to the general bedding scheme. They will flower for many weeks during summer.

Shrubs which flower in spring and early summer on shoots produced the previous season, such as flowering currants, forsythias, and lilacs, should be pruned as soon as flowering has ceased. Removing the shoots which have flowered encourages the growth of ample new ones which will produce flowers next spring.

Diseases and Pests

Geranium rust ruins many geraniums each year by causing rusty brown spots on the foliage. Fortnightly spraying with 2 fl.

; oz. of lime sulphur and | fl. oz. of , colloidal sulphur to 2 gallons of water i controls this disease. Before the plants . are sprayed badly affected leaves - should be picked off and burnt. ! Where the geraniums are growing against a house care must be taken L with sulphur sprays, for they dis- , colour paintwork readily. - Greenflies are prevalent in many gardens and attacks on them should ! be continued by spraying at 10-day ■ intervals with nicotine sulphate until ! they have disappeared. : Red spiders attack a wide .variety ; of pot plants and a careful watch : should be kept for them from now : on. The most efficient control measure I is spraying with summer (white) oil > or nicotine sulphate. If few plants are • to be treated, most of the red spiders can be eliminated by holding the I plants upside down beneath a fast- ; running cold-water tap. The treat- : ment should be'repeated at frequent ' intervals until there is no further sign ; of the pest. i ; . Rhododendrons are often attacked during summer by thrips which cause r ■ the leaves to assume a silvery appeari ance. The best spray against this pest l is one containing D.D.T., which is very J effective when applied at the rate of ■ 21b. of 50 per cent, wettable D.D.T. to J 100 gallons of water. ' Bibliography New Zealand Department of Agriculture Bul- ; letin No. 309, by F. Sydenham. Ontario Department of Agriculture Bulletin No. 448, by Shoemaker and Taylor. “Practical Lawn Craft,” by R. B. Dawson.