The protection which frames afford seeds and plants can be put to good use in several ways. A frame can be a safe harbour for tender plants during the wetter and colder winter months. Such shelter encourages quicker and earlier growth enabling the gardener to force certain crops out of season. Plants raised in the warmth of a greenhouse and intended for outdoor planting need to be inured gradually to more robust conditions and must, therefore, spend a little time in a frame where, by gradually admitting more air, cooler conditions obtain. This process is known as hardening off.
Types of frame
All frames have a deep back and a shallow front. The dimensions vary considerably, but there should be adequate room between the tops of the plants and the glass roof or light. Usually a depth of between 14 to 2 feet is allowed for at the rear, and about 12-14 inches at the front. Lengths and widths vary but, two popular sizes are 6×4 feet and 59 x 30i inches. The latter frame is a Dutch type which consists of one large pane of glass that is supported on a wooden frame of these overall measurements. The glass slides into rebates or grooves in the inside faces of the timber and is secured by a short wooden strip which is either nailed or preferably screwed into the base plate of the frame. No putty is used and it is a simple but expensive matter to replace broken glass sheets.
The former measurements are found in what can be termed the English type of frame, which has one or more longitudinal glazing bars which support small panes of glass. Both types of frame light are efficient, although the Dutch type allows slightly more light to enter owing to the small amount of timber used in its construction.
There are also variations in the methods of opening the frame lights. Most modern designs allow for the complete light to slide up or down along supports at the sides or at suitable intervals, if multi-lights are used. Some are hinged at the rear and are kept open by a prop of wood. Wooden frames Many frames are constructed from timber, either redwood or cedar. The latter is the better buy as it is resistant to rot and requires no painting. It is necessary to treat cedar once a year with special preparations to maintain its beautiful colour.
Some frames are constructed from metal, either galvanised steel or aluminium. Many more refinements are to be found in these designs such as handles, specially hinged tops and sliding glass panels. Several of these metal frames are of the span-roof type, like a greenhouse with an inverted V roof. This means that the frame has two working sides with two opening roof lights, one on either side of the ridge. An advantage with these frames is that there is much more headroom inside and, having glass sides, the maximum amount of light enters.
One range of metal frames is supplied with special runners or wheels and rails so that large units can be moved easily over the crops to provide a succession of forced or protected crops. Additional sections are also available so that the range can be extended.
Brick or concrete frames It is a big advantage if the frame can be made as warm as possible. This can be achieved by some form of heating and also by construction. If low brick or concrete walls are built and frame lights placed on top, a well protected and warm frame system can be made. They are, of course, of a permanent nature but should last practically a lifetime.
The latest frame designs are constructed from plastics and fibre-glass. The former are often quite cheap to purchase, the latter expensive. The plastic used for frames is generally confined to the construction of the lights themselves. Large sheets of tough polythene (usually 500 or 1000 gauge) are stretched and fixed to a light wooden framework. A few designs have similar sides and end sections. These models are light and easy to manage and will give excellent results except in cold weather when they tend to encourage condensation and afford little or no frost protection.
An ultra-modern de-sign is available in fibreglass with specially green tinted tough plastic sliding roof panels. Its appearance is very handsome and results with crops have proved most satisfactory. The size is approximately 4 x feet and the depth 14 feet. This type of frame can be cleaned easily and is light enough to transfer to other crops nearby.
Frames are usually un-heated but with the advent of safe electric warming cables it is quite easy to convert an unheated frame. The use of warmth in this way extends the versatility of the frame considerably and converts it into a miniature greenhouse. Farmyard manure will provide heat if it is used as a hot bed. This is composed of one or two barrow-loads of fresh, strong manure with a third part of dry leaves added. The heap of material is turned several times so that even decomposition occurs. It is important to see that the heap does not dry out too much during this process. In about ten days’ time thorough fermentation should be in progress.
The prepared heap should be spread out at the site so that it covers an area approximately 1 foot wider all round than the actual frame. The minimum depth of the manure and leaves should be 1-2 feet. The heap should then be trodden evenly all over, levelled, and the frame placed on the top. It is normal for fumes and moisture to be present at this initial stage, and under no circumstances should the lights be placed in position until these have been released. A layer of good loam is then added to a depth of 8 inches and levelled all over. A hot bed is most useful during the months of January through to April. A check with a thermometer should be made so that sowings or plants can be started as soon as the temperature of the hot bed has fallen to about 80-90°F (27-32°C). Electric heating by cables placed in the soil or around the inside walls of the frame is a much easier and cleaner system. Coupled to a reliable rod thermostat, the system becomes completely automatic and very reasonable in its running costs. Extra protection can be afforded if sheets of canvas, hessian or matting are placed over the glass during cold weather, particularly at night. A thick layer of straw can also be used or several thicknesses of heavy-gauge plastic sheeting. As soon as con-ditions permit, these coverings must be removed to allow light and air into the frame.
The site for the frame It is very import-ant to place the frame in the best possible position for good plant growth. Ideally, a frame should face south, but if this is not possible it must be situated where it is sheltered from cold prevailing winds and where it will receive the maximum amount of sunlight. A frame is an important adjunct to the greenhouse where it is used as a place to harden off plants which have been raised under glass. Used in this way, the frame should be placed as close as possible to the greenhouse so that the plants need not be carried far.
The frame should be positioned on well-drained ground, never where water tends to lie. If it is to be used without a green-house and is to be heated, it is advisable to site it close to the electricity supply to minimise installation costs. Many of the modern frame designs are attractive and do not look unsightly placed close to the dwelling house.
The soil and site for the frame need careful preparation. The area should be excavated to about 12-16 inches deep and a 3-4 inch layer of small rubble and weathered cinders incorporated. If the sub-soil is heavy, it should be broken up well beforehand with a fork. The remainder of the site should be refilled with a specially prepared compost. The various John Innes formulae are the best and can be made up at home or purchased ready mixed. The formula to be used will depend on whether the frame is required for seed raising or for the cultivation of plants to maturity. In a small frame it is a good idea to use seed boxes, pots or pans to maturity directly in the prepared frame soil.
It is surprising what can be done in a frame with a little preliminary planning. It is excellent as a propagator for a large number of seed-lings and cuttings. Seeds can be sown thinly broadcast in the frame soil, in neat rows, or in pots or boxes placed inside the frame. The time to start must depend on whether the frame is heated or not. If the frame is heated work can begin as early as midfebruary; in an unheated frame it is better to delay until about mid to late March.
The hardy and particularly the half-hardy annuals are ideal for frame sowings, to produce sturdy plants for planting out in the late spring and early summer. The following are worth a trial: salvias, neme-sias, China aster, antirrhinums, stocks, lobelias, petunias and Phlox drummondii. Late spring sowings may be made of perennials; polyanthus and delphiniums are especially good for this purpose. Poly-anthus sown in March and delphiniums sown in May, potted on into 3-4 inch pots make fine, sturdy plants for planting out into their flowering quarters in the autumn.
Cuttings can be raised in a frame to provide a wide variety of flowers. Good examples are chrysanthemums and dahlias. Chrysanthemum cuttings will be available from February until late April, depending on whether the frame is heated or not. Dahlia tubers boxed up in late March will also produce abundant cuttings. Protection from frost is necessary and a heated frame is better for this type of work.
Vegetables for frame cultivation
An ideal crop for frames. With careful management, heads for cutting can be grown all the year round. The use of suitable varieties is most essential, particularly for winter work. For cutting in March and early April, seed should be sown in late October and the seedlings planted 1 foot apart each way, in December. The varieties ‘May King’, ‘Early French Frame’ and ‘Attractie’ are suitable for unheated frames. For heated frames use ‘Chestnut Early Giant’.
Cold frame lettuces in winter need ample protection against frost and during dull, wet weather, ventilation must be provided to prevent mildew. It is a wise precaution to dust with sulphur. Do not over water; the ideal is to apply only sufficient to prevent the soil drying out. Lettuces are most welcome in the autumn and a sowing made in mid August will provide mature hearts from October on-wards. A suitable variety is ‘Attractie’.
To maintain regular supplies during the early summer and onwards, frequent small sowings will be necessary. Sow approxi-mately once every three weeks to maintain continuity. The first sowing in the spring should be in late February or early March. ‘Early French Frame’, ‘Market Favourite’ and ‘May King’ are three reliable varieties. For the early summer and main summer sowings, use varieties such as ‘Holborn Standard’, ‘Continuity’ and ‘Perpetual’. If there is a vegetable garden, these sowings can be made there to leave the frame free for other crops.
When young and tender, carrots possess an individual flavour and if these are grown as an early crop in the frame, a worthwhile supply can be easily produced. An early, forced crop is the best, and seed should be sown broadcast and as thinly as possible. It is essential that the soil be broken down as fine as possible before sowings. Suitable sowing times are January and February. Cover seed lightly and keep the soil moist. Lights must go on the frames immediately after sowing. Pickings should start in late May and early June. Suitable varieties are ‘Amsterdam Forcing’ and ‘Early Nantes’. The former is particularly suitable for unheated frames. Weeds must be removed regularly and as soon as they are noticed. Ventilation is also important and should be increased gradually as the season advances.
Turnips should be sown in late February or mid March for sweet roots in late May or early June, using seed of the variety ‘Early White Milan’. Sow in shallow drills, spacing these 10 inches apart. Early thin-ning of seedlings is essential so that there is room for the round roots to develop. Usually this variety is ready for pulling when the roots are about ai inches in diameter. The soil must be kept moist to encourage rapid swelling of the roots. Lights can be removed after mid April but a watch must be kept for late frosts.
Radish is another good crop for frames as it matures rapidly, given good growing conditions. Large crops are not required at any one time so it is better to use radishes as a catch crop between other slow-growing ones. Make frequent sowings at three-week intervals, if necessary starting in early February. The crop should be ready for gathering from late March on-wards. Shallow drills should be taken out for the seed between other crop rows and the seed sown very thinly. Water fre-quently and ventilate according to weather conditions.
Frames can be very useful to gardeners in the colder or more exposed parts of the country. Where space can be spared, a few outdoor tomatoes can be grown in a frame, the main purpose being to give important early protection so that sturdy, well-established plants are pro-duced. If a heated frame is available it will be possible to raise the plants from seed sown in mid March in pans or pots. A minimum air temperature of 50°F (10°C) is required. The seedlings should be pricked out into a deep seed box and finally potted on into 3 inch pots. They should be ready for planting out in early May.
Where an unheated frame only is avail-able, the sowing date must be delayed or, preferably, plants should be raised in a greenhouse or purchased for planting out in mid May or early June. For unheated sowings, seed should be sown in late April.
The number of plants which can be planted out in a frame must depend on the room available. Some of the dwarf or bush tomatoes are particularly suited to frame culture. These are planted out about 2 feet apart. For cordon or normal types, allow at least 2 ½ feet. Two excellent bush varie-ties are ‘First in the Field’ and ‘The Amateur’. For cordons any of the following are recommended: `Syston Cross’, Bapsfords No. l’ and ‘Leaf Mould Resister No. 1’. All are very resistant to leaf-mould (cladosporium) disease.
Cordon tomatoes should be staked early and stopped when they have made 3-4 good trusses. Bush tomatoes are not stopped. Feed when the first trusses have set their fruit and water regularly, par-ticularly when the fruit is swelling. A precautionary spray against potato blight is wise on outdoor tomatoes.
Frame or greenhouse types are suitable and are well worth growing, especially if there is no greenhouse avail-able. A rich soil is important and can be provided by working in old manure at each planting position. A hole should be excavated 18 inches deep and wide and half filled with the manure. Good soil should be placed on top. Where manure cannot be obtained, peat or composted vegetable waste are good substitutes. If more than one plant is grown, the planting sites should be 2 feet apart. Usually one plant is sufficient for a 6 x 4 foot frame.
Seed can be raised in early April, either in a greenhouse or in the frame, as for tomatoes. Plants from these sowings should be ready for planting out in late May or early June. Plant firmly and water well. Training is a simple operation. When a plant has made six leaves, the centre or growing point should be pinched out. This will encourage the plant to produce laterals, and four of these should be trained to the corners of the frame. If more than one plant is grown, two laterals should be retained and trained to one side or the other of the plant to allow plenty of room between the plants. When the later-als have reached the frame limits they should be stopped. Sub-laterals will form on them and these should be stopped also. The female flowers will be produced on these growths. All male flowers should be removed as soon as they appear, otherwise the fruits will be bitter after pollination. Stop shoots bearing a fruit two leaves beyond it.
Humidity is essential for frame culture and syringeing with tepid water should be carried out twice a day. The last application should be given before 4 o’clock in the afternoon to allow the foliage to dry before nightfall. Keep lights closed as much as possible to produce a warm, humid atmosphere. To prevent scorching, shade lightly with a proprie-tary preparation.
Keep plants well watered, although water must not be allowed to remain round the stems and roots. Feed with weak liquid fertiliser as soon as the fruits swell. White roots will appear frequently on the surface of the soil and these must be topdressed or covered with soil to a depth of at least 2 inches. Gather fruits regularly; in this way the plant will be encouraged to crop freely. Suitable varieties are ‘Conqueror’ and ‘Butcher’s Disease Resister’.
Melons do best in hot summers, nevertheless this is a crop which is worth a trial, especially in the warmer southern gardens. If there are no facilities for raising plants in heat in early May, they should be purchased from a reliable nursery or garden shop. Soil preparations are ex-actly the same as for cucumbers. Plant out in mid May or early June in an unheated frame.
Training and watering are as for cucumbers except that only 3-4 fruits should be allowed per plant if reasonable sized ones are to be expected. Unlike the cucumbers, hand pollination must be carried out with a small brush, transferring dry pollen from a male flower to a female flower. The latter is easily recognised by the tiny fruit immediately behind the base of the petals. In order to ensure dry pollen, the atmosphere of the frame should be kept dry when several flowers have formed.
When fruits have set and are swelling well, place a piece of board under each one to prevent marking and slug damage. A little slug bait should be placed in the corners of the frame. Feed as for cucumbers and topdress with soil whenever necessary.
Melons are ripe when a heavy odour or perfume is noticed and when the area immediately around the stalk begins to crack. The area around the flower end also becomes soft. Varieties to use are ‘Dutch Net’ or ‘Tiger’. Both are cantaloupe melons with attractive orange flesh.
Marrows are usually grown in the open garden, but an earlier planting and crop-ping season can be achieved if a frame can be spared. Culture is the same as for cucumbers. The best type to grow is the bush, which requires no special training. Good varieties are ‘Improved Green Bush’, ‘Superlative’ and ‘Tender and True’.