Pests

Insect Fumigants For Greenhouse

A chips Greenfly and black th are among the most common ofthe greenhouse insect pests. They normally cluster together and arc easily seen with the naked eye. Aphids are sap suckers and if present in large numbers their feeding soon checks the plant's growth they are also major carriers o virus diseases. They can be controlled with a variety of chemicals. earwigs These are likely to damage open flowers by eating the petals they are particularly active at night. The hollow ends of garden canes...

Plants Healthy

This chapter could have been titled 'controlling pests and diseases', but that would have misrepresented its essential aim. There can be little doubt that every greenhouse gardener, whether amateur or professional, has at one time or another had to deal with plants that have been attacked by pests or infected by disease. Equally, every experienced gardener will tell you that prevention is better than cure, and that the most effective method of keeping pests and diseases at hay is to ensure that...

Flowers for cutting

Chrysanthemums are probably the most widely grown cut flowers. It is not difficult to have them in bloom from September through to January provided the appropriate varieties are chosen and a little heat is available. Following on the propagation period in the spring, the plants are best left outdoors during the summer months, and rehoused in September just before the autumn frosts begin, The cur-flower grower with a little heat available may find that roses and carnations, grown either in pots...

Capillary benching

This is the term used to describe benching constructed so as to allow plants growing in pots to be watered automatically. The bench becomes in effect a trough of water, the level of which is critically controlled by the water being 'absorbed' into a matting covering or a layer of sand. The compost in the plant pots must establish good contact with this surface, so all crocks must be removed from the bottom of the pots. When setting out the plants press each one firmly on to the bench. If...

Greenhouse

I Choosing a Greenhouse 6 2 Services and Equipment 22 3 Planning 30 4 Flowering and Foliage Plants 5 Food Crops 58 6 Plant Propagation 74 7 Keeping Plants Healthy 80 8 Maintenance 88 A Calendar of Greenhouse Work Index 96 First published in 1979 by Simdiai Public at ions Limited C gt row nor Sirect, London Wl 1979 Helmerwoml Pu til i cj ri gt ns Lifnitcd Printed ii England by Sever i Valley lJress Limited

Electricity

For many greenhouse owners a supply of electricity will be essential to make the best use of their investment. It will be needed for interior lighting, so that greenhouse work can be done in the evening after work during the short days of winter and spring. Ordinary incandescent lights will be suitable for tins. Electricity may also he needed Kir heating a propagating frame, and local heating of this type can be the most economical way of propagating plants, Electric soil-warming units are...

Pathways

Greenhouse Gardening

It is very important to keep the greenhouse clean at all times, and good pathways can make a helpful contribution to this. Paths of hardened soil invariably encourage puddles to form when plants arc watered and on clay soils the resultant slippery surface is both dangerous and messy. If the borders are used for crops, permanent pathways are not recommended because they can harbour soil pests and diseases, in such cases removable pathways are preferred duckboards are cheap, but 50 mm 2 111 thick...

Water

Greenhouse plants need a considerable amount of water, especially on hot, sunny days, and it is essential to ensure that the water, from whatever source, is not contaminated in any way. As a rough guide to quantities required, a single sturdy tomato plant carrying several trussc- of fruit will require at least i.s I 21 pints of water per day applied to the root zone, in addition to that required for spraying over the foliage and damping down tin greenhouse. rainwater If the greenhouse has been...

Growing mediums

Greenhouse Seedling Pots

Loam composts Special growing mediums have been developed for container-grown greenhouse plants, and the more important ones are described in this chapter. For over JO years the John Innes composts have been used by commercial growers and amateur gardeners alike. The name John Innes is taken from the research station where they were formulated after years ot investigative work. The formulations provide horticulturists with various growing mediums to cover every greenhouse activity, from seed...

Choosing a Greenhouse

Choosing Greenhouse Structure

Tim purpose ot a greenhouse is to provide plants with a more sympathetic growing environment than would Impossible in the open air. While providing plants with all the light they need, a greenhouse offers both heat and protection against wind. The earliest ancestor of the greenhouse was the high stone or brick wall built around a cultivated area. Such walls offered not only wind protection but, by retaining heat from the sun's rays, conditions warm enough to grow relatively tender crops in the...

Plasticcovered greenhouses

Undoubtedly the biggest rival nowadays to the conventional greenhouse is the polythene-covered structure, of which several designs arc available. Its popularity is due to its relative cheapness, resulting trom the simplicity of the framework and thesold-in-a-carton approach. The basic framework in most cases is of tubular alloy or galvanized steel, and 6oo-gaugc polythene sheeting is the usual covering material. Several factors affect the life of the sheeting so ti is not easy to be definite as...

Greenhouse Glass

Replacing Glass Greenhouse

Glass used in horticulture is usually 3 mm thick 24 oz sq ft and the standard quality available is generally good, Nevertheless, when buying a greenhouse it is as well to enquire what weight, or thickness, of glass is supplied whether it is ot British manufacture or imported whether it is supplied directly by the retailer or comes from a glass distributor and what arrangements there are for replacing panes of glass that might get broken in transit. It is a sensible precaution to examine a...

Greenhouse Work

As the Christ mas-flowering chrysanthemums timsli flowering cut them back hard and box up those stools from which cuttings will be taken later. Bring 111 rhubarb for forcing and plant the crowns under benching if space is available. In soil-warmed borders and frames sow 'Forcing French Breakfast' radishes, 'Amsterdam Forcing' carrots, and 'May Queen' lettuces. In the south of England it is time to start the propagating season. Take cuttings of the autumn-flowering chrysanthemums and sow seed of...

Sowing Tomatoes In March

Start Dahlia Pot

Owners of unhealed greenhouses or propagating equipment will not have been able to do much in the way of plant raising to date, but from now on they will have to use every bit of space. The emphasis this month should be on seed and plant propagation. Sow tomatoes for cool and cold greenhouse growing also cucumbers, courgettes, and sweet peppers. Make further sowings of radish and. where emphasis is on early vegetable production, sow beetroot, carrots, and turnips. From March through to June sow...

Growing methods

Carnation Alice Forbes

The following is a selection ot flowering and foliage plants commonly grown in the greenhouse by amateur gardeners. There arc, of course, hundreds of such plants suitable tor growing under glass or plastic, but space allows us to deal with only a few. The selection is, however, varied enough to plan a range of alternative programmes, including mixed cropping with food plants str Chapter 6 , Each pot plant should be regularly examined for signs ul posts and diseases Each pot plant should be...

Propagation by seed

Compost Heated Greenhouse

Propagation by seed is an inexpensive way to raise many types of greenhouse plants, although in the case of slower-growing Species ii may take much longer to obtain a worthwhile specimen. Generally, individual plants raised Irom seed are not identical to their parents nor to one another, but such variation is often scarcely noticeable because, over a period of years, seed raisers select the 'truest strains. You will find that catalogues from reputable seedsmen contain more and more seeds that...

Whalehide Container

Container Type Greenhouse

A- most greenhouse flowering plants are grown in pots. I should perhaps make a few general observations about these containers. Pots are available 111 a great variety of sizes, shapes, and materials- The sizl- of a pot is defined not by us height hut by the inside dia Plant pots end seed containers are made in a variety of materials for different uses meter of the rim. The range of standard sizes includes 65 mm 2 ' in , yo mm 3 in , 130 mm 5 in , and 180 mm 7 in the so-called half-pots half the...

Heat and ventilation

Given adequate light, one of the most important attributes of a greenhouse is the way it deals with the potentially conflicting needs ot heat retention and ventilation. Greenhouse designers ha ve devoted much thought to the problem of retaining heat. Some years ago double glazing seemed likely to be the answer. In practice, however, the method has serious disadvantages the two layers of transparent material cut out a great deal of light the sun's rays take much longer to heat the greenhouse and...

Erecting an alloy greenhouse

Erecting Greenhouse

Many greenhouses are now supplied in pack form Be careful to check that Mil the listed components, screws, nuts, bolts, and so on are present before you begin erection. Although alloy frames are light In weight, you may need another pair of hands at this stage m order to prevent the sections from flexing The site needs to be raked level to provide a solid support for the base. Keep Ihi1 greenhouse as far away as possible from any solrd fences that would cast a shadow on it. Take care to follow...

October

Should be received this month pot them directly into 200 111111 fi in pots but do not bring them into the greenhouse until late December. Sow tomato seed in heat if the earliest fruits are required. Box up the mid-season and late-flowering chrysanthemums. Check for draughts at doors and ventilators, and if necessary fit draught-excluders to retain heat. Clear 150-gauge polythene sheeting fixed along the sides ot the greenhouse will reduce draughts and conserve heat do not take it completely up...

Heating equipment

Greenhouse Heating Machine

A greenhouse affords plants protection from the elements, and tor this reason they usually grow better than they would out ot doors in the same location. Unhealed glasshouses provide a little protection from frost ofthe order of 2 to _V C , but uuheated polythene Rtghl above Temporary slatted shelving should not be used, as here, for storing Dots or other equipment When not required it should be dismantled to admit mote light. Right below Permanent shelving provides useful extra space, but it...

Ventilation

Greenhouse Vents

Greenhouses need to be ventilated to prevent temperatures rising above those best suited to the plants being grown high temperatures lead to stress within the plants and may cause wilting. Ventilation is also required to control humidity levels within the greenhouse. Tomatoes, for example, require a humid atmosphere at least once a day for an hour or two to allow the flowers to set, but for the remainder of the time they like a drier atmosphere. Setting the ventilation by hand involves guessing...

Propagating equipment

Mist Propagation Unit

Roots will develop over a period of months, and when they can be seen through the polythene the newly rooted plant should be severed from the parent and potted. grafting I his method is rarely used to propagate greenhouse plants, with the occasional exception of tomatoes. But since tomato growing is an important feature ot most home greenhouses, the method used for these plants deserves to he mentioned here. The value ot tomato grafting is that it enables the grower to graft selected...

Vegetative propagation

Grafting Plants

T his is a form ot propagation 111 which pieces ofa plant are removed and rooted in the soil. Unlike plants raised from seed, those resulting from vegetative propagation are identical to their parents. Plants from which material is taken need to be carefully selected, tor if there is disease such as a virus present it will automatically be transmitted. On occasions plants undergo a physiological change known as 'sporting'. A white chrysanthemum may sport yellow flowers, and yellow varieties...

Thermal screens

Any method of conserving heat is important in view of the steadily rising cost of fuels. I have already stressed the importance of light and the disadvantages of double glazing. The ideal is to have maximum light during daylight hours while preventing too much heat loss during the hours of darkness. This is the thinking behind the fitting ot thermal scrcens, which are now being used increasingly by commercial growers. The screens act as a form of blanket over crops and their future adaptation...

The structure

Glazing Tape Glass Wood Greenhouse

Painted wooden greenhouse frames will need exterior painting every four to five years and interior painting every five to six years. An exterior-grade white paint of good quality should be used. An undercoat as well as a topcoat will be required if the old coats are stripped down to the wood, knots must be treated with knotting and a primer will need to be applied before the undercoat. The wood must be perfectly dry when paint is applied, and on the glazing bars the paint should lap mm -1 in on...

Diseases

Greenhouse Tomato Diseases

Botrytis cinerea Commonly known as grey-mould disease, Botrytis is a fungus that attacks a wide range ot plants, particularly 111 coid, wet spells. It usually gains entry through damaged plant tissues, and it is a particularly troublesome source of damage to overwintered crops in unheated and cool greenhouses. As its name suggests it develops a fluffy grey mould on the infected plants, it is best prevented by keeping the foliage and stems of plants dry when the temperature is low and keeping...

Checklist of insecticides and fungicides

The following tables set out most of the important insecticides and fungicides that the greenhouse gardener is likely to use. They are based on information in the Directory of Garden Chcmicals, 4 th edition London 1979 . published by the liritish Agrochemicals Association. Must insecticides and fungicides are available in liquid form and are applied by spraying others are sold as aerosols, powders, granules, or pyrotechnic fumigants, All are quite easy to use. but be careful to follow the...

Soil sterilization

It the greenhouse border soil or frame is occupied year after year by the same crops, soil sterilization becomes essential. The ideal sterilant is steam, and steam sterilizers may be available for hire from the larger equipment-hiring shops. Removing the soil from the border, sterilizing it, and then replacing it is, however, a long and laborious process. An alternative method is thoroughly to soak the soil with a 2 per cent solution of formalin. This chemical has the drawback that its fumes...

Insecticides and fungicides

Greenhouse Fumigants

Sprays, dusts, and fumigants often aerosol-applied are ways of bringing an active chemical ingredient to bear against pests ,iod disease organisms. Small sprayers of the pump-up type are relatively inexpensive and reliable, and the shaped lance helps to get the spray on to otherwise inaccessible parts ot the plant. A nozzle producing fine droplets should be used, and the sprayer Lighting a greenhouse pyrotechnic fumigant Lighting a greenhouse pyrotechnic fumigant must be cleaned thoroughly...

Physiological disorders

Physiological Disorders

Tomatoes suffer from a number of such disorders. 'Greenback' is the name given to fruits which, when ripe, still have green or yellow patches on them. It is a less common disorder than formerly owing to the introduction of resistant varieties. Cracked fruits occur as a result ot a sudden upsurge of moisture into the plant this often happens after soil which has been allowed to become too dry recei ves ,1 good soaking Dnmping off disease ol ppa seedlings Dnmping off disease ol ppa seedlings of...

Other methods

Enormous advances have been made in plant-breeding techniques in recent years and it is certain that 'breeding in' resistance to pests and diseases will become increasingly effective. A strikingly successful example of this may be seen in the development ot the tomato rootstock KNVF, which gives resistance to corky root, root-knot eel-worm, verticillium, and fusarium. Tomato varieties resistant to leaf mould, greenback, and tobacco mosaic virus have also been bred and are generally available...