CHAPTER 9
Winter
The coldest winter weather doesn’t usually arrive until mid-winter so early winter is usually the last chance to protect those not-so hardy specimens in the garden.
GENERAL MANAGEMENT
Early winter
Cautious watering and ventilation should be continued. Shut down ventilators at night, opening them only on sunny days. Again, maintain a minimum temperature of 45°F (7°C) at night and around 54°F (12°C) during the day for the majority of greenhouse plants.
Wash down the greenhouse and remove all debris, if not already done.
It is probably worth insulating any greenhouse that is heated during the winter months. Deciding what type of greenhouse insulation to buy depends to a large extent on the temperature lift required: that is, the difference between inside and outside temperatures.
The simplest form of insulation is polythene sheet. This can be attached to the greenhouse structure using pins on wood or special clips on aluminium. The idea is to create a still, insulative layer of about ½in (1.25cm) between the side of the glass and the polythene sheet. If sheets are not properly joined together or tend to move with the breeze then much of the insulation effect is lost.
For very leaky greenhouses it’s best to plump for the more expensive, but more effective, bubble polythene. However, this again must be put up properly to gain the maximum benefit. This type of plastic double glazing does reduce light levels a little, but not too drastically.
One of the major restrictions to greenhouse gardening in the winter months is light. If you heat your greenhouse up too much there is a real chance of plants producing weak spindly growth because of lack of light. This can be a particular hazard with early sown crops like pelargoniums and tomatoes. Many lamps are available for the greenhouse to supplement existing light and to extend day length.
Bubble plastic makes a very effective insulator.
EARLY WINTER QUICK REFERENCE CHECKLIST
Water and ventilate cautiously.
Insulate the greenhouse.
Light levels are critical, so consider using artificial light.
FLOWERS
Sow Campanula isophylla.
Cut back greenhouse chrysanthemums.
Water calceolarias, cinerarias, cyclamen and primulas carefully.
VEGETABLES
Harvest plump white chicons from forced chicory.
Continue to sow a succession of lettuce for continuity of supply.
FRUIT
Carry out complete winter pruning of grape vines.
Top-dress peaches and nectarines.
Ventilate freely.
Mid-winter
Mid-winter is usually the coldest time of the year and this can curtail gardening activities unless there is a greenhouse to hand. A heated greenhouse can be an inspiration of colour with primulas, calceolarias, cinerarias and cyclamen all brightening up an otherwise dull garden. Those with enough space for an Indian azalea or arum lily will be in for a treat at this time.
A careful balance must be maintained between heating, watering and ventilation during the tricky first few months of the year.
Watering cyclamen must be carried out with meticulous care, making certain that the foliage and more particularly, the crowns of pot plants are not soaked. This will cause rot to set in and the dramatic collapse of foliage. It is best, therefore, to water from below during the early part of the day – soaking each plant thoroughly, then not returning to water again until the compost is quite dry. Do not overwater.
Incidentally, where a cyclamen plant does collapse it is worth checking the corm and root system for vine weevil larvae, which eat the fleshy roots. Where vine weevils are discovered throw out the affected plant and treat others with an insecticide or biological control (see ‘Controlling Pests Without Chemicals’).
Skilful ventilation is the secret to keeping fuel bills down. During bright, sunny, windless days open the ridge vents to allow a little air circulation within the greenhouse. On breezy days open the ridge vent on the leeward side of the greenhouse. Don’t ventilate during very windy weather. When the vents are open it is worth shutting them a couple of hours before dusk to capture some of the sun’s energy and give the heaters a head start.
All heaters and automatic ventilators should be checked regularly at this time of year. Paraffin heaters, in particular, need regular maintenance and filling, but don’t be tempted to neglect the less demanding heating systems since any type can fail.
Maximum/minimum thermometers are an essential aid to the greenhouse grower, giving an accurate assessment of the temperature of the previous night. Use this information to adjust your heating and ventilation balance.
General maintenance of the greenhouse should not be neglected either; replace cracked or broken panes of glass promptly. Check insulation for gaps or sagging particularly in the roof sections – and fix where necessary.
Check all overwintered stock of cuttings taken during the autumn. Remove and compost any yellowing leaves. Watch out for botrytis, grey mould fungus, because this can play havoc in the greenhouse at this time of year. Also peruse all your flowering plants on a regular basis, removing dead flowers promptly.
Daffodils, tulips and hyacinths can be brought inside from the plunge beds (sited in a sheltered spot in the garden) to maintain the continuity of flowering plants in the greenhouse. Don’t send them into shock, though, by making this transfer too rapid; it is best to put them in a cold frame for a couple of days first.
Cold greenhouses that are standing empty can be given the full clean-up treatment – scrubbing down the greenhouse structure and sterilizing soil and compost (see also Chapter 8). Any recent vacated or forgotten pots and seedtrays should be cleaned and stored in readiness for the busy sowing season ahead.
WINTER CHECKS
1. Check all nuts and bolts and tighten any that have worked loose.
2. Check that all vents close snugly. Replace any broken panes.
TIP
Many house plants will now be suffering from the low light levels that occur indoors at this time of year. So it is worth bringing them into a heated greenhouse on a rota basis to keep them happy.
Schefflera ‘Umbrella Tree’.
MID-WINTER QUICK-REFERENCE CHECKLIST
Careful heating, watering and ventilation is essential.
FLOWERS
Sow pelargoniums, salvia, gloxinia, hollyhocks and snapdragons.
Sow sweet peas for showing.
Take carnation and chrysanthemum cuttings.
Plant amaryllis, fibrous-rooted begonias and gloxinia tubers.
Pot up rooted cuttings.
Prune overwintered fuchsias and some greenhouse climbers.
Feed budding calceolarias, cinerarias and primulas.
VEGETABLES
Sow early tomatoes for heated greenhouses, dwarf French beans, leeks and onions.
Chit seed potatoes.
Plant early pot-grown potatoes and rhubarb for forcing.
FRUIT
Start early vines in a heated greenhouse.
Late Winter
In most years, late winter is a calm, dry and cold time. Greenhouse heaters are often working flat out day and night to maintain the required temperature but still the heated greenhouse will reward us with a bounty of colour throughout the period. Again many primulas, calceolarias, cinerarias and cyclamen are in bloom. Early sowings can be made now in a heated greenhouse, but if you delay until early spring next month, you will save money on heating costs.
Hygiene is important at this time of year when ventilation is limited and temperatures are down. Systematically purge the greenhouse of dead and dying leaves and promptly remove flowers that are past their prime. Check for pests and diseases now to prevent them getting an early foothold. Spray as necessary.
Ventilation is of paramount importance but once again, it should only occur during calm, sunny spells. Don’t be tempted to open up the vents on dank, misty days or when there’s a keen wind blowing that might cause a drop in temperature inside the greenhouse. Automatic vents can be a problem at this time of the year because they tend to open too wide and remain ajar right into the evening, losing valuable heat right at the end of the day.
Watering must be given as and when necessary – a great deal more will be required by plants in active growth on bright, sunny days. Most winter watering is best done from below by standing the pot plant in a tray and then adding water or immersing the pot up to its rim in a bowl of water for a few minutes. Whichever method is used, a pot plant must be given an opportunity to drain fully before being returned to its position on the staging.
Opuntia subulata.
The weather dictates most activities in the green-house and none more so than heating. The choice of cleaning, filling and trimming the wick of paraffin heaters, makes them unpopular these days. In addition they have to be lit every time the temperature threatens to plummet. Other forms of heating need less maintenance and are often thermostatically controlled to make them more fuel efficient. But even these systems should be checked regularly just in case something goes wrong. After all, it only takes one penetrating frost to wipe out all your early starters.
It is not worth heating the entire greenhouse just to get a few garden crops off to an early start. It is far better to invest in a soil-warming cable and install it in a partitioned-off section of the greenhouse. Soil-warming cables are cheap to run and provided there is already an electricity supply are easy to install (see also Greenhouse Equipment, Chapter 3). The heat produced by soil-warming cables raises the temperature of the compost in pots and seedtrays placed on top – this speeds germination and encourages root development. If you intend to install one buy it now to realize maximum benefit from your investment.
Check through the stock of pots and seedtrays to make sure they are ready for use as well as ensuring there are sufficient labels for the coming season. Sit down and run through the sowing programme for the weeks ahead to check there will be continuity of supply through the season. Use rubber bands to group packets of seeds that can be sown at the same time under the same or very similar conditions. This highlights those requiring special treatment. Make a checklist for all these jobs otherwise something is bound to be forgotten.
LATE WINTER QUICK-REFERENCE CHECKLIST
Keep on top of greenhouse hygiene; wash and sterilize pots and seedtrays.
Continue careful heating, watering and ventilation.
Check insulation.
FLOWERS
Sow half-hardy annuals and perennials.
Sow sweet peas, bedding dahlias and several greenhouse pot plants.
Take cuttings from chrysanthemums and carnations.
Plant achimene tubers.
Prune greenhouse fuchsias, bougainvilleas, gardenias and overwintered pelargoniums.
VEGETABLES
Sow early melons and cucumbers for raising in a heated greenhouse.
Sow broad beans and early peas if not done in autumn.
Sow early lettuce, cauliflower, cabbage and Brussels sprouts.
FRUIT
Hand pollinate early peaches, nectarines and apricots as well as early vines.
Bring potted strawberry runners inside.
PROPAGATION
Flowers
Perpetual-flowering carnations can be propagated in early winter from cuttings. Do not select shoots from too near the top or the base of the plant. Take 3in (7.5cm) cuttings, snapped cleanly out of the parent plant. Trim them up using a sharp knife and dip the cut end in hormone rooting powder. Stick cuttings around the edge of a 3½in (9 cm) pot filled with gritty compost.
Chrysanthemums can be propagated as soon as suitable material is being produced by the stocks. Decorative varieties that were cut back to within 6in (15cm) and overwintered in the greenhouse will be producing fresh young shoots by mid-winter.
1 Select basal shoots around 3in (7.5cm) long that are not too drawn. Some varieties are a little slow in producing basal shoots, so encourage them by adding a few handfuls of fresh compost around the stool and increasing the temperature a little. Wait until shoots are around 4in (10cm) long before taking cuttings to leave a ½-1in (1–2.5cm) snag that will rapidly produce another set of shoots.
2. Use a sharp knife to remove basal shoots from the stool, then trim the cutting to just below a leaf joint.
3. Dip cut ends in hormone rooting powder.
4. Insert prepared cuttings either singly in the cells of a modular seedtray or two per 3½in (9cm) pot filled with a gritty cuttings compost with a layer of silver sand on top to aid drainage. Where many cuttings are being taken, insert them 2in (5cm) apart in boxes filled with compost. Water well.
Cuttings will not require watering again, but it is worth spraying the tops with water to prevent them from flagging too much. Although heat is not required, best results are obtained if the cuttings are placed in a propagator and given a little bottom heat. Rooting should occur within two or three weeks.
Perpetual-flowering carnations can be propagated from cuttings from early winter. They will produce sideshoots from nodes right up the stem. When taking cuttings, avoid shoots close to the top of the plant as well as those around the base.
1 As with the decorative chrysanthemums, take 3in (7.5cm) cuttings, which should be snapped cleanly out from the leaf joint of the parent plant.
2. Using a sharp knife, trim up the base, dip it in hormone powder and shake off excess.
3. Push cuttings into a modular seedtray filled with cuttings compost, or around the edge of 3½in (9cm) pot. Water well.
4. Place in a propagator and give a little bottom heat, 61°F (16°C) if possible. Rooting will take place within a few weeks provided the tops are prevented from wilting.
Cuttings can be taken from chrysanthemums and carnations throughout the winter.
Border dahlias can be increased in late winter.
1 Select some healthy tubers that have been stored over winter in a cool, dark, frost-free place. These can now be boxed in a moist peat and sand mix with their crowns clear of the surface.
2. Place in a warm, light position so the tubers swell and start to produce shoots suitable for taking cuttings. You should aim for a temperature of around 61°F (16°C) for a good supply of short-jointed, fresh green shoots.
3. When new shoots are 3–4in (7.5–10cm) long, cut them off with a sharp knife, leaving a ½in (1.25cm) stump from which the new shoots will develop.
4. Then treat as softwood cuttings (see Propagation, Chapter 5).
Where side shoots of overwintered plants are long enough, they can be used as cutting material in early winter.
Trim each cutting just below a leaf node using a sharp knife and remove lower leaves. Dip the end in hormone rooting powder and insert into a gritty cuttings compost. Maintain a temperature of around 61°F (16°C) for speedy rooting.
Seed
Sowing starts at a gentle pace in mid-winter with half a dozen or so different plants. Many will germinate admirably with a temperature around 59–64°F (15–18°C) – most economically provided by a propagator – although pelargonium, salvia and gloxinia prefer a couple of degrees more warmth.
Early sowings are particularly prone to attacks by fungus diseases. It is, therefore, worth making these sowings thinner than normal to allow better air circulation between the seedlings. Also water with a fungicide such as ‘Cheshunt Compound’ to give protection. Don’t be tempted to go overboard with these early sowings because they will have to remain in the greenhouse until late spring when space is always at a premium.
With the onset of late winter, sowing begins in earnest, so get yourself organized. Make sure there is enough compost for the coming weeks.
Many half-hardy annuals can be sown in late winter, destined to decorate beds and borders throughout the garden. Take care not to sow too much at this stage, otherwise you may run out of space for later sowings.
Bedding dahlias need to be sown during late winter or early spring in a seedtray at a temperature of 61°F (16°C). Germination will quickly occur and new seedlings should be potted up individually as soon as they can be handled safely. The dwarf ‘Coltness Hybrids’, ‘Rigoletto’ and ‘Redskin’ are tried and trusted varieties.
MAIL-ORDERED SEED
Ordered seed will be arriving from the seedhouses from early winter. They must be stored in a dry, frost-free place to keep them in top condition. There is still time to make fresh orders for seeds and young plants by mail order. Remember though that many suppliers of seedlings and tiny plants have a last orders deadline in early spring.
SOWING SWEET PEAS STEP-BY-STEP
Sweet peas can be sown in late winter, but those destined for the local flower show can be sown in early winter provided they are given heat.
1 Lay blotting or tissue paper in a shallow dish and soak with water.
2 Lay the seed on the paper, then cover with another sheet of wet paper. The seeds will soon swell and produce a radicle within three or four days. Any seed that doesn’t respond by swelling should be nicked to encourage water absorption.
3 Place germinated seed individually in special sweet-pea tubes, about ½in (1.25 cm) deep in a peat-based potting compost (or J.I.P. No 2), or sow three or four seeds per 3½in (9cm) pot.
4 Protect against mice feasting on the seed by covering sown pots with a sheet of glass.
Alternatively, soak seed in warm water for twenty-four hours before sowing to speed germination. Sow three or four seeds about ½in (1.25cm) deep in ½in (9cm) pots. Water thoroughly and maintain a temperature of around 61°F (16°C).
Vegetables and Fruit
In mid-winter, a range of early vegetables can be sown, the most important of which is the early tomato. You will need either plenty of room or not intend growing much else if you embark on cultivating early tomatoes in a heated greenhouse for first harvest in early summer. Tomatoes need consistent heat, so a reliable well-regulated heating system is necessary to give a minimum temperature of 64°F (18°C) from seedling stage until established. Temperatures can then be reduced gradually to 55°F (13°C) at night until plants are ready for planting out, when a minimum of 50°F (10°C) should be aimed for. If your heating system is not capable of maintaining such high temperatures early on or is not 100 per cent reliable then it would be wise to delay sowing until early spring, or buy in plants in mid-spring. Producing early tomatoes is an expensive gamble.
1 Sow very thinly. Tomato seed is large enough to sow singly so space six rows of four across a standard seedtray.
2. Cover the seed with ¼in (6mm) of compost, water thoroughly, then place a sheet of glass and a newspaper over the seedtray. Maintain a temperature of 70°F (21°C) for quick germination, but 59–86°F (15–30°C) would do.
Check the seedtray each day and wipe condensation off the glass to prevent drips falling onto the compost and emerging seedlings.
3. Remove the glass and newspaper as soon as the first seedlings break through, then put the seedtray in a light position to prevent the seedlings from becoming drawn. Keep out of direct sunlight.
Sow tomato seed individually, well spaced.
4. When the first true leaves are expanding, lift the seedlings carefully and pot up individually into 3½in (9cm) pots. Do not handle them by their stems but hold one seedleaf between finger and thumb while supporting the root system with a small dibber or plant label. Discard any odd looking or small seedlings since they invariably both develop and fruit poorly.
The earliest crops of dwarf French beans can also be sown in mid-winter and can be grown in the greenhouse borders before maincrop tomatoes put them in the shade. Varieties like ‘Masterpiece’ and ‘The Prince’ are often recommended. Sow 1in (2.5cm) deep during the latter half of mid-winter in peat pots in a temperature of 61°F (16°C). Water well. Plant out in the greenhouse border 6in (15 cm) apart when roots start to show through the pot. Alternatively, sow five seeds in a 6in (15cm) pot filled with a peat-based potting compost (or J.I.P. No. 2).
Large onions and leeks for showing can be obtained if they are sown during mid-winter, in heat under glass, ready to be planted out as sturdy seedlings as the weather improves in late spring. Maintain a temperature of 61°F (16°C) for best results, with seed sown individually in the cells of a modular seedtray or thinly in a standard seedtray filled with sowing compost.
To maintain a continuity of firm, crisp heads of lettuce in spring, sow the variety ‘Ricardo’ direct into the greenhouse border. From sowing to harvesting takes just three or four months in a heated green-house and up to five months in an unheated one.
Lettuce can be sown and harvested throughout the winter.
In late winter, the first crops of outdoor lettuce can be sown in a temperature of 55°F (13°C). Varieties such as ‘Avondefiance’, ‘Little Gem’ and ‘Great Lakes’ should be sown ¼in (6mm) deep into peat blocks or fibre pots for best results. Once germinated, harden off in a cold frame and plant outside from mid-spring onwards provided the weather is suitable. Alternatively make further sowings of the ‘Iceberg’ type lettuce, ‘Marmer’, direct into the greenhouse border where the temperature is kept above freezing for harvesting in late spring.
Bright scarlet radishes like the variety F1 ‘Cyros’ can be sown in succession from mid-autumn to midwinter in an unheated greenhouse to provide a much welcomed supply of fresh salad in early spring.
For an early crop of cucumbers, sow in late winter, provided there is a good heating system that is 100 per cent reliable. Only one sowing is necessary since the plants will, with luck, crop the entire season if given the correct treatment. Try an all-female variety such as ‘Flamingo’ which can yield for several months. Select 3½in (9cm) pots and sow two seeds per pot as for melons. Cucumbers require a gemination temperature of around 24°C and can be emerging in just a week or so. Remove the weakest seedling from each pot.
If you were unable to sow broad beans last autumn they can be sown in late winter in pots in the greenhouse. Use 3½in (9cm) deep in a peat-based seed compost. No heat is required – just frost-free nights. Even a well-insulated frame would do. Harden off in early spring for planting out in mid-spring.
Sow early pea varieties such as ‘Little Marvel’ and ‘Early Onward’ if the mid-autumn sowing directly outside was missed. Sow in pots. A novel method is to sow in a compost-filled gutter pipe. Sow two rows 2–3in (5–7.5cm) apart with seed staggered down the pipe. A temperature of around 55°F (13°C) will be sufficient.
The slow-to-germinate aubergine (egg plant) should be sown under glass during late winter. Sow singly into peat pots filled with sowing compost and maintain a temperature of at least 64°F (18°C).
If you have a heated greenhouse it’s a good time to make first sowings of cauliflower; cabbage and Brussels sprout. Again a temperature of around 55°F (13°C) or slightly above is ideal. Sow seed very thinly in a seedtray or individually in a modular seedtray using a sowing compost.
Start to harden off autumn-sown early-summer cauliflowers for planting out in early spring.
Melon seed needs to be sown in succession from late winter until late spring if you want plants cropping all summer. Early sowings will need a well-heated greenhouse for the first few months. The easy to grow ‘Sweetheart’ that produces sweet and aromatic fruit and the productive ‘Ogen’ with its delicate pale green flesh are two varieties worth considering.
1 Sow two seeds in a 3½in (9cm) pot filled with compost. Place each flat seed on its edge to prevent rotting, about ½in (1.25cm) deep using a small dibber.
2. Place pots in a tray and water. Allow the pots to drain, then lay a sheet of glass and a piece of paper over the top and maintain a temperature of at least 64°F (18°C) but preferably 70°F (21°C). (The glass will also protect the seed from avaricious mice that find melon seeds irresistible.)
3. Check the pots each day and remove the glass and paper as soon as the first seedlings appear.
POTTING, PLANTING AND STARTING
Flowers
Chrysanthemum and carnation cuttings taken earlier in the season should have rooted by mid-winter. Pot them up individually into 3½in (9cm) pots filled with a peat-based compost (or J.I.P. No. 1), which will prevent their growth from being checked by lack of nutrients in the cuttings compost. Take great care when teasing roots apart to prevent damage.
Take further cuttings from carnations, and place all recently potted plants in a light, but cool spot out of direct sunlight.
Cyclamen seedlings sown in autumn can also be potted up.
Hippeastrums that flowered last year can be brought into growth in mid-winter. Every two or three years they will need re-potting. Using a peat-based compost (or J.I.P. No 2) in a 6in (15cm) pot, plant one bulb so that it is about two-thirds buried. In subsequent years just remove the top layer of compost and replace it with fresh. Aim for a temperature around 15°C and the bulb will soon produce the flat green tips of the leaves, quickly followed (and sometimes preceded) by a plump flowerbud. Water and feed as soon as growth is apparent.
Gloxinia tubers can also be started off now if you can keep a temperature of about 70°F (21°C). Place tubers in a tray or box filled with moist peat to encourage the swelling buds into growth. Then pot each tuber up singly into 6in (15cm) pots filled with potting compost such as John Innes potting compost No. 2. It is probably better to choose loam-based compost because the plants get top heavy.
Once potted, grow plants in a lightly shaded position in a temperature of about 64°F (18°C). Keep well watered and feed once a fortnight.
Standard fuchsias that have filled their 5in (12.5cm) pot and grown beyond the supporting split cane will be ready for moving into an 8in (20cm) pot. Replace the split cane with a 4ft (1.2m) long bamboo and pinch back sideshoots to the first pair of leaves.
In late winter, pot up achimenes grub-like tubers to get an impressive display in several glorious colours. Six or eight tubers can easily be accommodated in a 6in (15cm) pot and will give a good display. Either plant about 1in (2.5cm) deep direct in the pot using a proprietary potting compost or lay the tubers on the surface and give them a slight covering of compost. Once sprouted they can be potted up. Whatever the method used, the tubers should be watered well and kept in a temperature of 61°F (16°C) until signs of growth can be clearly seen.
Standard fuchsia.
Subsequently the plants should be fed at fortnightly intervals. If you have enough tubers it is a nice idea to stagger the starting dates of each potful to get an extended flowering display.
Vegetables and Fruit
Seed potatoes become available in mid-winter. Select healthy medium-sized tubers and set them in trays with the plumpest eyes uppermost. Keep in a frost-free position (under staging is ideal) – where they’ll begin to sprout (chit). Also keep them out of reach of mice.
It is possible to plant a few tubers of early varieties such as ‘Maris Bard’ and ‘Suttons Foremost’ into large pots where they’ll grow and produce a plateful of succulent early potatoes in mid- and late spring. A large pot or tub is required (12in; 30cm) diameter) for forcing early potatoes:
1. Cover the base with a 2in (5cm) layer of compost, then arrange three healthy, chitted tubers on the surface and cover these with a further 2in (5cm) of compost.
2. Water well and keep in a light place maintaining a temperature of 50°F (10°C).
3. As the fresh green shoots appear, topdress the pot with further compost to leave a couple of inches of shoot standing proud of the compost’s surface. Repeat until the pot is full.
Rhubarb crowns can be selected for forcing under greenhouse staging if not already done. Plunge them close together in a crate filled with moist peat, then cover with black polythene to encourage succulent pink shoots (right).
You need a lot of space to grow fruit successfully in a greenhouse. Vines, peaches, nectarines, apricots and figs all benefit from a heated environment, but they are so demanding that little else can be grown with them.
A high temperature of 61°F (16°C) is required if you want to start vines off in late winter, with a minimum night temperature of around 45°F (7°C) over the early spring period. A humid atmosphere must be maintained, which does not always fit in with other crops, and no ventilation should be given except on clear, still days. Feed and water well. Suitable varieties include ‘Black Hamburg’, ‘Foster’s Seedling’ and ‘Alicante’.
Pot-grown strawberry runners that were rooted during mid- and late summer should be brought inside and potted into 5in (12.5cm) containers. These plants need to be started into growth very gradually, raising the temperature slowly to about 10°C at night. When new growth appears, increase water rations. Several varieties are recommended including ‘Idil’ and ‘Pantagruella’.
FEEDING, WATERING, HEAT AND AIR
Once chrysanthemums have finished flowering in the greenhouse and are carefully labelled cut back to about 6in (15cm) and carefully remove the debris. Light and air will then get down to the crown to encourage basal growths.
Charm chrysanthemums that have finished flowering need to be cut back. Keep them just moist in a frost-free position under the staging in the greenhouse or in a spare bedroom. Shoots will break from the stools during the next few weeks and make ideal material for cuttings if you wish to increase your stock for display next year.
Christmas cactus should be kept moist and fed once a week with a weak liquid fertilizer. Do not move the plant once it has budded up, otherwise you risk bud drop. Also keep it away from draughts, and give sufficient water to prevent too dry a compost, as neglect of either of these points will have the same effect.
Cyclamen will be flowering in early winter. They are particularly vulnerable to rot, so careful watering from below is a must. Regularly remove dying leaves and flowers by giving a sharp tug at the base of the stem.
Forced bulbs will need to be brought in from plunge beds if they are to be ready for mid-winter. Some folk like to sow grass seed around the bulbs to complete the decorative effect.
Feed pot plants like calceolarias, cinerarias and primulas with a high-potash fertilizer to encourage flowerbud production.
Clean up the greenhouse and scrape away at the loose flaky bark on the vine. Don’t get carried away, but take it down to the smooth, brown bark underneath. Take care not to damage the buds though. Removing the loose bark will reduce the pest and disease problems for next year by either spoiling their winter hide-aways or, more importantly, exposing those already hidden to an insecticide. Paint on an insecticide containing malathion for best results.
Eye cuttings are used for the fruiting Vitis vinifera cultivars. They should be taken from woody one-year-old stems during winter. Remove one of the buds and dip base in hormone rooting powder. Insert in cuttings compost so that only the bud is showing. Water in and place in a propagator at 70°F (21° C). Top growth will occur before rooting takes place.
Remove the top inch or so of compost from the surface around fruit in the greenhouse and replace it with fresh loam. Dust on some sterilized bone-meal and sulphate of potash. Ventilate freely in order to keep temperatures down.
POLLINATION
During late winter, peaches, nectarines and apricots in a well-heated greenhouse start to come into flower. They are normally insect-pollinated but in the greenhouse this is a far from reliable method so some form of assistance must be given. (See the section on pollination in Chapter 6.)
Vines also need hand pollinating when they come into flower, which will be a month or so after they were started into growth.
Unheated greenhouses with vines should be well ventilated during the day to prevent plants shooting away too early and risking frost damage to the soft, young growth.
PINCHING OUT AND CUTTING BACK
Fuchsias grown as bushes will need pinching out a week or so after potting up from their 3½m (9cm) pots into 5in (12.5cm) containers.
Aechmea.
Some greenhouse climbers such as the passion flower (Passiflora) need to be cut back in midwinter if they’re not to look straggly all season. Remove all weak and diseased shoots and prune back the current year’s growth to a healthy, plump bud about 6in (15cm) from the main stem. Where the plant is becoming too big for the space available thin some shoots back to the main stem or even to ground level and cut others back as already described. Bougainvilleas, gardenias and pelargoniums need a trim after their winter rest. Cut back to about 6in (15cm) and repot with fresh compost.
OVERWINTERED FUCHSIAS
Overwintered fuchsias should be pruned back to produce a well-structured framework. Make each cut to an outward-facing bud ½in (1.25cm) or so from the main stem for standard types and to within 2in (5 cm) of the crown for bush varieties.
Of course, all weak, tangled, diseased or dead growth must be completely removed.