How to mow a lawn
Lawn construction and maintenance
Most gardeners regard a lawn as an important, if not essential, feature of the garden. The lawn may in fact be the major feature, being a big expanse suitable for garden parties and surrounded by sufficient flower beds to set it off. Alternatively, the lawn may be a minor feature designed to set off flower beds. In either case the requirement is usually a good lawn, ie one which has a uniform cover of good grass and which is free of weeds and blemishes caused by disease, earthworm casts and the like. A lawn which is mainly for children's play or for use as a drying ground does not demand the same high standard as does the real ornamental lawn but should, at any rate, be capable of being regarded without horror!
Layout The general shape and contours required should be decided at an early
stage, always bearing in mind that about 16cm (6in) of top-soil should remain overall on completion with gradients designed to allow easy mowing in more than one direction and to allow surface water to escape, without collecting into hollows. The nature of the site—its contours, shape and features such as the levels of the paths, doors, existing trees or rock outcrops determines the form of the new lawn. Generally, simple contours and shapes with no awkward corners or mounds are most satisfactory and these can often be produced with little movement of earth. More ambitious programs require stripping the topsoil before carrying out the necessary grading in the sub-soil. It is not necessary to think exclusively in terms of a square or oblong patch of lawn surrounded by borders. Some measure of landscaping should be introduced and an irregular shape can be planned with borders of varying width. The site can also be broken up by minor undulations, by terracing, by a shrub break or it can be combined with a crazy path, a rock garden or other features. The effect should nevertheless be bold rather than petty and frivolous.
Clearing the site The first step is to remove as thoroughly as possible any builder's debris or old ironwork, tree roots, etc. There may even be the odd load of gravel which can be used elsewhere. Small bushes and long grass can be cut and burnt.
Grading On a great many sites, a new lawn can be made without major
alterations in the levels and, in fact, few of us have the energy required to embark on extensive work of this kind. There is no need for the lawn to be absolutely level but it should, of course, be smooth to whatever gradient is accomplished. A gentle slope, say 1 in 80 is, in fact, quite a good thing to help shed surface moisture during rain. Minor adjustments in levels can be achieved by moving top-soil, always subject to the limitation that at least 16cm (6in) (or at any rate a minimum of 10cm (4in) of good top-soil must obtain everywhere on completion. Sometimes it is convenient to buy in a few loads of top-soil to improve levels.
Where considerable grading is required, the really hard work of stripping the top-soil so as to allow grading in the sub-soil is necessary. Such work may have to be accomplished in sections because of space limitations. The topsoil is piled up on one side and the sub-soil gradients altered (usually by cut and fill) before returning the top-soil. There will be few sites where it is necessary to become very technical and use various devices to achieve satisfactory levels; most people will be able to manage satisfactorily by the use of pegs, string and possibly a straight edge.
It is important to remember that soil handled in wet conditions is adversely affected and particularly so where machinery is brought in to help out. Care should be taken to work under dry conditions if at all possible.
Drainage On many sites, particularly where grading has been carried out by machinery, the sub-soil as well as the top-soil is heavily consolidated and, unless this consolidation is removed, the moisture penetration is severely impeded. On relatively small areas, double digging may be needed in order to break up both the sub-soil and the top-soil. On larger areas the sub-soil cultivation can be achieved by means of a tractor-drawn sub-soiler which is usually best used in two directions after replacement of the top-soil.
Whether or not tile drainage or any other form of drainage is required depends on individual site peculiarities. From experience it would seem that most people are able to manage without drainage for their lawns but certainly the possible need for drain-pipes ought to be given some consideration. Clearly, it is not possible to have healthy grass and a good lawn if the soil is waterlogged. On wet land a simple line of clayware land tiles will often suffice provided that some form of outlet can be provided. It is best if the drains can be connected to a main drain somewhere since soakaways, while not without merit, are seldom entirely satisfactory.
On large lawns on wet land a proper herring-bone system of drainage may be
wanted and whenever land tiles are
used it is a good plan to cover them with coarse gravel or clinker ash to within
about 16cm (6in) of the final surface of the lawn this being covered finally with 16cm (6in) of top-soil (ie no sub-soil).
Preparing the top-soil All debris such as large stones, big plant roots etc,
should be removed and all steps taken
to prevent contamination with sub-soil or any deleterious material. Digging is
the first operation and any old turf which
exists should be buried. If this digging is done in autumn or winter the soil may
be allowed to weather during frost. The
land can then be worked down by Dutch hoes, rakes etc, in the drier spring
weather. During the preparation of the
soil it is a good idea to improve it by digging in various materials. Thus, on
really heavy soil up to 50kg (lcwt) of
gritty lime-free sand per sq m (sq yd) can be worked in with advantage and also on
such sites, to keep the soil open after
the lawn has been made, up to 3.5kg (71b) of granulated peat per sq m (sq yd)
may be advantageous. Light sandy land
benefits from organic materials designed to improve moisture-holding capacity.
Well rotted stable manure at say 7-14kg
(14-281b) per sq m (sq yd) is an excellent thing but this is in short supply and may
have to be substituted by such things as leafmould or granulated peat (up to 3.5kg (71b) per sq m (sq yd).
The next thing is to try and ensure that the prepared land is free from
roots and seeds of undesirable plants
which may establish themselves and compete with the new grass. The best way of accomplishing this is to give a complete summer's fallowing, ie allowing the weeds to germinate and then
raking or hoeing them out. To take some exasperation out of all this it is
a good plan to grow a potato crop or similar which gives some encouragement and return for the work involved. Chemical cleaners have some merit but they are not the complete answer to the problem.
Whether the lawn is to be established from seed or turf, the final preparations
are fairly similar in that in either case
we need a firm, fine soil bed. Repeated cultivations and consolidation are
needed. The site may be broken down by means of a Canterbury hoe or mechanically as seems most appropriate and then rough raking follows with the removal of the larger stones. To try to eliminate air pockets in the body of the soil it is wise to 'heel' the surface, an operation which involves close treading with the weight of the body thrown on the heels so that the soil is pressed down into the soft spots. For this operation the soil should be dry enough not to adhere too much to the boots.
Further raking and heeling at right angles to the first set of operations should follow. Final working should aim at achieving a smooth surface from which small bumps and depressions have been entirely eliminated while the soil is sufficiently firm (though not over compacted) to minimize the risks of sinkage later producing an uneven surface. A rather better tilth is required for seeding than for turfing.
Turfing This is popularly accepted as being the best way to produce a satisfactory lawn. This is not strictly true, but undoubtedly the use of turf does simplify matters for the amateur and does make possible the use of less perfect soil conditions. Unfortunately good turf is both rare and expensive so that many people become disappointed with the lawns they have obtained by this method. Frequently the supplier is blamed for the unsatisfactory results despite the original acceptance of the turf as satisfactory, there possibly having been some mistaken idea that the turf would
improve after laying. There is now a British Standard Specification for turf so that purchasers buying to the standard have some control over what they receive, though they may in fact require a higher standard than that covered. The major gain from turfing is that of time, since the turf can be laid in the autumn when it is too late for seeding and with good management can appear as a really good lawn, capable of being used, the following summer. Turf laid in spring and summer runs the risk of drying out and not establishing satisfactorily.
Great care should be taken when buying turf, which should preferably be established in soil of a sandy loam nature and free from stones. The delivered turf should be in mown condition, of close texture and good uniform density and color. There should be sufficient fibre to hold the turf together for handling but excess leads to unsatisfactory results. The quality of grasses in the turf which is bought depends on the requirement but for a first-class lawn there should be little in the turf except fine bent and/or fescue grasses and, even for second-class lawns, weeds and diseases should be absent.
The delivered turf is best in 30cm (1ft) squares (or possibly 60 by 30cm (2 by 1ft) and cut to a uniform thickness of say 3cm (1in). If the turf which arrives is uneven in thickness it may be desirable to box the turf, ie to lay the turf, roots up, in a shallow tray of suitable depth and then draw a stout knife across the top edge of the box, thus bringing the turf to the standard thickness.
Before laying the turf the soil should receive such chemical treatment as is required. Acid soils may need lime and this is best decided as the result of a soil test. Usually it is wise, whatever the nature of the soil, to give a fertilizer on the following lines :
3kg (61b) of fine hoof and horn meal
3kg (61b) of fine bone meal
3kg (61b) of powdered superphosphate
1.5kg (31b) of sulphate of potash
per 100 sq m (100 sq yd).
The fertilizer should be raked in, preferably a few days before, laying the turf.
When the actual turfing operation starts it is wise to choose weather conditions when the soil is reasonably dry to avoid damage to the prepared site. On many sites it is convenient to start by laying a single turf round the perimeter of the site. After that, laying turf across the body of the site should be done in a forward direction, working to face the unturfed part which should be maintained in its prepared condition. Traffic should be on planks laid across the turf as required. The turf should be laid with broken joints, rather like bricks in a wall. Each turf should be laid flat and tight up to its neighbors. Where a turf seems to be either high or low adjustment should be made in the soil below rather than by beating down etc. When the whole of the turf has been laid it should be carefully rolled with a light roller and then a sandy compost material applied at 2-3kg (4-5lb) per sq m (sq yd) and carefully brushed in.
Seeding The best time for sowing grass seed on a new lawn is about the end of August. Spring sowing are not ruled out entirely hut they do run a greater risk from drought since May is often very dry and in the spring, weed competition tends to be greater than in the late summer. Seeding is the cheapest and
probably the best way of getting a good lawn but the best results are only achieved if sufficient skilled work is put into the work of seeding and of looking after the lawn in the first year or so.
In the final stage of preparations and a few days before sowing a suitable complete fertilizer should be given and this might well take the form of:
1.5kg (31b) of sulphate of ammonia
1.5kg (31b) of fine hoof and horn meal
1.5kg (31b) of dried blood
3kg (61b) of powdered superphosphate
3kg (61b) of fine bone meal
1.5kg (31b) of sulphate of potash
per 100 sq m (100 sq yd)
This should be carefully raked into the soil a few days before sowing. Soils of an acid character should have been limed appropriately a week or two earlier.
The kind of grass seed to use depends on the kind of lawn required and on the amount you are prepared to pay. For a first-class lawn a really fine mixture such as 8 parts of Chewings' fescue (preferably a good variety such as `Highlight') and 2 parts of browntop bent (American origin) is suitable and the rate of sowing is about 28g (1 oz) per sq m (sq yd). Less fine mixtures may be used for hard-wearing, second-quality lawns and, for children's playground type of lawns, even coarser mixtures containing perennial ryegrass may be used. For all these grass seeds a rate of application of 28g (1 oz) per sq m (sq yd) is satisfactory. There are, of course, good proprietary mixtures available from reputable lawn seed suppliers and generally speaking one can go on price.
Sowing is best done on a dry, raked surface and it is wise to divide the seed into two lots for sowing in transverse directions. For really careful work it is best to divide the lawn into sections and weigh out the amount of seed for each section and then again split this into two halves for transverse sowing. The seed should be lightly raked in and there has to be emphasis on the lightness of this operation, particularly for the very fine mixtures, since the grass seeds should not be deeply covered. It is not usually necessary or desirable to roll after raking but rolling will be needed when the grass is showing through in order to tighten up the soil round the grass roots preparatory to mowing.
The question of bird damage often arises in suburban areas and certain preparations are sold for treating the grass seed. These are of limited benefit in that frequently most damage is done by birds not so much eating the seed as spoiling the seed bed by having dust baths! The best protection is usually the very elementary one of having black cotton across the lawn supported by sticks. Some people lay polythene over the newly-sown lawn area but if this expedient is used it is important to get the cover away as soon as the grass shows through or disease attack may well undo all the good work and certainly do more damage than the birds.
After-care Lawns which have been established by turfing need occasional top dressing with bulky material such as sandy compost or of an artificial compost made up from soil sand and peat. The purpose of this dressing is to smooth out the surface and fill in any cracks, so it needs careful working in by a suitable drag brush or other piece of equipment. Occasional rolling may be required but this should not be overdone. During the first year the grass will need mowing regularly but over close mowing should be avoided, particularly if it shows signs of skimming any prominent piece of turf. In the spring following turfing a good general fertilizer should be given as for an existing lawn.
New-sown lawns should not be mown until the grass is about 5cm (2in) high and then it should be carefully topped, preferably using a side-wheel machine which is sharp and in good condition. Before mowing, stones should be picked off the surface and the area carefully rolled. Mowing should then be done when the grass has regained its upright condition. Any coarse grass or weeds which appear in the new sward should be removed by hand at intervals but mowing will dispense of annual weeds satisfactorily. On no account should the grass be allowed to get too long and regular mowing is essential with the height of cut being gradually lowered to the chosen final height. A lawn which has been sown at the end of the summer or early autumn will not need any further fertilizer treatment until the following spring. It should then receive a dressing of general fertilizer such as for an existing lawn.
The surface levels on a seeded lawn are unlikely to be as good as those of a turfed lawn and occasional top dressing with sandy compost at about monthly intervals during the first full year's growth will help to produce the smooth surface which is such an attractive feature of a good lawn. A few weeks after sowing, bare patches which have been missed despite the best endeavours may become visible and at this stage it is useful to have reserved a small quantity of seed so that over-sowing can be carried out straight away with the result that the patches soon catch up.
On new-sown turf the disease called `damping-off' sometimes attacks, more particularly when heavy rates of seeding have been used or when a normal rate has been washed by heavy rain into concentrated collections in heel marks or similar depressions. Sometimes reovery occurs by natural means but if the disease is serious it is necessary to treat the grass with a suitable fungicide such as Cheshunt compound, which is applied by means of a watering-can, or more conveniently with an inorganic mercury fungicide applied as a dry dust.
Maintenance The essence of a good lawn is that it is uniform in texture, color and surface smoothness with freedom from patches caused by weeds, disease, earthworms, or bad mowing. The lawn needs to be sufficiently hard-wearing to stand what is required of it and it should maintain a good color both in summer and in winter. This color at the various seasons is in part a reflection of the grass variety, in part of the feeding and in part of moisture control. The earth should hold sufficient moisture to keep the grass growing in dry weather but should not be waterlogged in winter.
Mowing Regular, not too keen mowing, is essential if the lawn is to be attractive and satisfactory. The first requirement is a good mower in good condition and, of course, buying mowers has much in common with buying cars. Personal choice comes into the matter as well as the engineering performance and the price. For best results the most expensive conventional mower (roller type) of a given size may well be the best and, of course, an important factor as far as grass is concerned is the number of cuts to a linear yard. A motor mower has advantages in reducing muscular effort particularly on large lawns but it is wise to buy as light a machine as possible since regular use of a heavy machine results in considerable compression of the top soil.
A new lawn should not be cut too high at first but gradually worked down to the height of cut that is required. It is a mistake to cut very short since no grass really thrives on such severe defoliation. The really fine grasses of a first-class lawn stand the closest cutting but even they should not be cut closer than 1-2cm . For medium lawns 2-3cm is suitable, while for ryegrass lawns 3cm (1in) is more satisfactory since rye-grass (even the best varieties) does not like mowing any shorter. For lawns which are not required to be very fine many people use the so-called rotary mowers. Infrequent mowing damages the grass and during the vigorous growing season a good fine lawn needs mowing as much as three times a week while even a second-class lawn should be mown not less than once a week. It is an advantage if the lawn can be mown in different directions each time it is cut.
Less frequent mowing is necessary when growth is not vigorous but at no time should the grass get very much longer than its accepted height. Even during the winter months careful topping in the right weather conditions may be desirable. At whatever time of the year the lawn is being mown, the best results are produced if the operation is carried out when the grass is dry.
Although allowing the cuttings to fly means the return of plant foods, it is nevertheless considered wise to remove cuttings since they encourage disease, weeds, earthworm castings, coarse grasses and a soft surface.
Edging No matter how good a lawn is produced it looks second rate if the edges are not kept trimmed. Most owners of small lawns use ordinary hand shears for cutting the grass at the edges but long-handled shears or special lawn edge trimmers are more favored if the lawn is large. Even when given regular attention, edges tend to become uneven and attention with a straight spade or turf cutter is required about once a year. Permanent edges of metal, wood or concrete have decided advantages in keeping clean lines round the lawn.
Top dressing For a really good finish from mowing it is necessary that the surface of the lawn be smooth, otherwise you will find long grass in the hollows and skimmed turf (and later, moss) on any high patches in the lawn. Obviously the smoothness of the surface owes something to the original preparation of the lawn and rolling will help to push down some of the higher areas. Unfortunately rolling accomplishes this smoothing out at the expense of producing consolidation and this is not good for root development or for moisture penetration. Rolling must, therefore, be kept to a minimum.
The best way of achieving a really smooth surface is to follow the practice of professional groundsmen or greenkeepers, ie top dressing the surface with bulky material of suitable texture. What is best for most lawns is a sandy compost material which might be made up for example by mixing sand, soil and peat to make a product of a consistency something similar to good potting compost but, of course, without any added fertilizers. This material is spread over the lawn by hand or shovel fairly evenly and then worked into the surface by means of a drag mat or drag brush.
On small areas the back of a wooden rake can be used to work the material backwards and forwards so that it disappears into the base of the sward, obviously going preferentially into hollow areas. Care must be taken to avoid smothering. Amazing benefits in the appearance of the lawn can be achieved by this often neglected practice.
Fertilizer treatment Requirements for fertilizer on existing lawns vary considerably: on rich soils fertilizers may
not be needed more than once in five or ten years while on poor soils where wear
on the lawn is heavy, two good fertilizer dressings a year may be advisable. On average, once a year is at least enough and a reputable brand of lawn fertilizer can be given each spring. If you wish to know what you are putting on, you may care to make up a mixture yourielf on the following lines:
1.5kg (31b) of sulphate of ammonia
0.5kg (11b) of fine hoof and horn meal
0.5kg (11b) of dried blood
2kg (41b) of powdered superphosphat
e 0.5kg (1 lb) of fine bonemeal
0.5kg (11b) of sulphate of potash
per 100 sq m (100 sq yd).
Such fertilizers must be well mixed with sandy soil or similar material to the extent of about 12kg (281b) of this per 100 sq m (100 sq yd) in order to give more bulk to help uniform distribution and also to minimize scorch risk. The addition of 0.5kg (11b) of calcined sulphate of iron per 100 sq m (100 sq yd) to the above mixture helps to improve grass color and to check weeds and disease. Careful, even, spreading of fertilizer is best carried out during showery weather but if no rain falls within one or two days of the application, the fertilizer should be watered in to avoid damage to the grasses.
An experienced professional groundsman obtains the best distribution by hand spreading and the amateur gardener should not despise this method though it needs to be done carefully. Small distributors are available but difficulty is always experienced in matching up adjacent 'breadths' to avoid missing strips or overlapping. while the turns also worry many people.
Liming A good gardener has to use lime occasionally in many parts of the country but he should not transfer this wise practice to the lawn since liming encourages weeds, worms and disease in the lawn. The soil sometimes does, in fact, become too acid and require liming but the disadvantages of liming are such that it pays to try to make sure that liming is really necessary before starting. The soil test, of course, is the ideal way. When liming a lawn a light dressing only, of a material such as ground limestone (ground chalk) is needed at a rate of 50-100g (2-4oz) per sq m (sq yd). Excess of lime encourages worms, weeds etc and reduces the proportion of fine grasses.
Mechanical operations While a great deal of mechanical work is necessary on bowling greens, golf greens, tennis courts etc, it is possible to overemphasize the amount of work required of this kind on the average lawn.
Nevertheless, regular brushing or light raking of the lawn keeps the grass in good condition, prevents the formation of excess fibre and keeps the grass growing vertically to give the appearance of a nice, new carpet with the pile standing upright. Light raking also brings up the runners of weeds such as clover and thus prevents them from spreading. On old lawns which have become over-fibrous, vigorous scarification with a wire rake to get out some of the fibre is a good idea. Such vigorous work is best carried out at the end of the summer while there is still sufficient growth to heal up any disfigurement which might be caused, or to a less severe extent in the spring when growth is beginning. If you have a large lawn you may be able to use a mechanical scarifier.
Rolling is useful in the spring to firm up the ground after any upheaval caused by the winter frosts, but after that its use should be kept to a minimum if, in fact, it is done at all following the first spring rolling. This, of course, is because of the consolidation which rolling creates.
To compensate for over-compaction some kind of aeration of the soil is occasionally desirable, but on the average lawn it should not be necessary to do this heavy work annually. Much depends on how much compression is produced by the amount of wear given, by the weight of the mower etc, but probably on the average lawn some kind of forking every three or four years would be sufficient. There are so-called hand forks which can be used. They are pressed into the ground by the foot and make holes which allow water and air to penetrate and also encourage rooting. If there is severe compaction it is wise to use forks which have hollow tines which remove a core of soil, thus allowing the surrounding soil to expand and thus, of course in turn relieving the pressure. The grass roots very well down these holes and it will be appreciated that a good deep root system helps the resistance of the grass to drought and indeed to wear and tear. Some of the special forks for aerating the lawn have solid tines which may be cylindrical or flat in shape. These do not make such a complete job as the hollow-tine forks, but on the other hand they do not leave holes which are easily invaded by weeds. There is no doubt at all that hollow tine forking can be overdone. Various types of machine, ranging from hand pushed to complex motorized models, are available for carrying out forking work and in view of the labor involved, if you have a large lawn, you will no doubt consider purchasing or hiring such a machine.
Watering Grass cannot grow without sufficient moisture, so that in dry weather a really good lawn needs artificial watering occasionally to keep it at its best. Watering should start early on in the dry weather, ie before the grass starts turning brown and the watering should be done quite copiously when it is done at all, so that the moisture penetrates deeply down to the roots. Light damping of the surface from
time to time may do more harm than good by encouraging surface rooting and thus making the grass more liable to damage by drought. Many gardeners apply water to their lawns by means of the hosepipe with some kind of spraying device at the end, but a simple kind of sprinkler, of which there are many now available, is extremely useful and, in fact, may be so used as to water the lawn and the adjacent flower beds at the same time. Where difficulty is experienced in getting the water to penetrate, shallow spiking is useful to start the moisture penetrating the surface.
Artificial watering is not an unmixed blessing in that it tends to encourage annual meadow grass and weeds such as pearlwort, especially if the water is hard.
Weed control If management practices are satisfactory, weed invasion is kept to a minimum but some weeds will always manage to invade even the best kept lawns. The problem is fairly easy to deal with these days since the new selective weedkillers are so effective. Generally speaking, it is best to use one based on a mixture of the chemicals 2, 4-D and CMPP of which there are a number of proprietary compounds available. Repeated applications may sometimes be necessary for resistant weeds. The best conditions for using the weedkillers are when growth is active. when the weather is warm and the soil moist, though there is little prospect of rain, which reduces effectiveness. It is important to ensure that the chemical does not get anywhere but on the lawn since obviously all broad-leaved garden plants and greenhouse plants are susceptible. Any containers used should be carefully and thoroughly washed out before they are used for other purpose. Weedkiller applications are normally best carried out by means of a sprayer but, particularly in small gardens, sprayers are not recommended for lawn use since risk of spray drift on to plants in the flower beds is considerable. It is better to use a watering can fitted with a fine rose or with a dribble bar attachment. Uniform distribution is, of course, essential since missing strips means that some weeds will be untouched, while overlapping or excessively generous treatment to a given weed patch may cause severe damage to the grass.
Moss causes a great deal of anxiety to lawn owners—sometimes out of all proportion to the amount of moss. Usually moss in a lawn is a sign that there is something wrong somewhere in the management; either the lawn is starved, or is mown too severely, or has bad drainage, or is suffering too much from the shade of trees and buildings.
Even low shrubs slightly overhanging the lawn can result in moss invading the shaded area and then spreading. The first essential, if moss is to be eliminated, is to find out the cause and to remove it or ameliorate it as far as possible. If this is done, then good results against moss can be obtained by using proprietary preparations containing mercury compounds such as a mercurized turf sand.
Pests The most important pest on a lawn is the earthworm. Generally the earthworm may be the gardener's friend but on the lawn the detrimental effects of the casts are considerable. They make the surface dirty, while their tunnels make the surface soft and the whole effect is that the lawn is wet and muddy. In addition, the casts smother grasses and act as first-class seed beds for weed seeds which may be brought up from below with the casted soil or which may be blown in from elsewhere. The use of lime or excessive amounts of organic fertilizer, or the retention of cuttings on the lawn, all of which encourage earthworms, should be avoided. It is better (and cheaper) if worms can be kept out rather than that they should have to be treated with chemicals. If it becomes necessary to control the earthworms by chemical treatment, mild conditions in autumn (or, rather less satisfactorily, in spring) when the worms are actually working near the surface, provide the best conditions. The two materials most usually used by professionals are lead arsenate and chlordane both of which are poisonous so that many lawn owners would prefer not to use them, especially where there are children and nets. Probably the best material to use in such circumstances would be one of the proprietary derris preparations sold for the purpose. The powder preparation can be applied dry and either watered in or may be left to be watered in during the next rain storm. Most of the earthworms die below ground with this treatment but a few will come to the surface and should be removed. Even derris products cannot be used if there is a fish pond adjacent, since derris is very poisonous to fish.
There are few other pests of lawns (other than the neighbors' pets) but leather-jackets are occasionally troublesome, particularly near the seaside and these can be dealt with by BHC or like powders sold for the purpose.
Diseases The most common disease of lawns is that known as fusarium patch
disease (or snow mould) and this is most frequently met on over-fed lawns, particularly in damp, shaded situations.
Another fairly common but less damaging disease is corticium which shows as
brownish discoloration, generally over
quite large areas. This fungus disease is usually associated with insufficient feeding and quite often a dressing of fertilizer is the best remedy, but fungicidal treatment may be necessary to cure bad attacks.
Renovation From time to time patches of lawn become bare as the result of burning with fertilizer or wear and it is necessary to make these good. Sometimes it is convenient to bring a patch of turf' from a less important part of the lawn but often it is necessary to prepare the earth and sow a little grass seed, and protect it from the birds. If the edges of the lawn become bare the best procedure is to strip the outside band of turf carefully, say 30cm (1ft) wide, to replace with turf cut from the next 30cm (1ft) of the lawn, and then put the worn turf in place of this. The thin turf can then be overseeded. See also Grass seed for lawns.