It is fantasy time again. The dispiriting reality of winter's gales and rain fosters extravagant dreams. Mine presently centre round a conservatory, a leafy, scented, luxurious bolt-hole that I could escape into as the wind howls down the chimneys of the house and the rain beats down the last remnants of the monkshoods and verbena in the garden.
A fantasy conservatory is far easier to manage than the real thing. Whitefly, red spider mite, scale insect, heating bills have no role to play. And the space that you play with in your mind is always more elastic than the real thing could ever be. Feeding the fantasy requires regular forays to other people's conservatories, to see how they do things. At the National Trust garden at Wallington in Northumbria, there is a splendid old lean-to conservatory with fish-scale glazing that I copied when we built our greenhouse.
When frost had brought the flowers outside almost to a standstill, plumbago was still rampaging up the pillars inside and fuchsias, in enormous glazed pots, were dripping with flowers. Smaller clay pots, filled with a vast array of flowering plants, were clustered together on the flat workbench that ran along under the lowest side of the building.
I would want doors either end of my conservatory (a lean-to for preference), and a working area divided from the main space where I could rest plants and bring others on to put in the display house in season. The floor would be stone or unglazed terracotta tiles, something that could be sloshed over fairly regularly with water.
Shading would be a problem as most new conservatory owners find out in their first summer of occupation. Blinds are a common option. That would be too domestic for the conservatory I have in mind. I think I would experiment with reeded glass, if I could get hold of it, or, since this is a fantasy and I don't have to think of cost, wooden slatted shades, fixed to the outside of the building. I'd also train vines along the ribs of the roof to provide shade. The advantage of vines is that they drop their leaves in winter, when the conservatory needs maximum light.
The disadvantage of vines is that nobody has yet invented one that is proof against mildew. Spraying an indoor, overhead vine would be a pretty horrible job. So it's obvious already that in my fantasy conservatory, I put plants before people. This isn't an extra sitting room. It's an extra garden and picking up vine leaves from the floor would not be a problem, but a pleasure, protected in this mini-Eden from the wild weather outside.
The key to running a successful conservatory, I've learnt from those who have them, lies in choosing the right plants. That seems a simple enough message, but easier to fulfil in the kind of conservatory I have in mind, a damp, rather cool planthouse, with perhaps an odd, concessionary rattan chair or two. The majority of conservatories are hot, dry, fully furnished and with the sort of floors that their owners do not want to see permanently running with water.
These conditions most closely approximate to a hot, dry Mediterranean climate, but the sort of plants that are perceived as conservatory plants are the leafy plants of the tropics, where > humidity is always high and winter temperatures are not all that different to summer ones. So mimosa, olive trees, citrus of various kinds, hibiscus, bougainvillea and pandorea are likely to do better than strelitzias or calatheas, arrow-leaved caladiums or bromeliads.
The answer to a happy winter in a conservatory is some forethought in May, which is the best time to introduce the predators that will keep on top of most of the kind of pests that haunt conservatories. Whitefly is the most difficult to eradicate. I've not been much bothered about it until this year, when it moved wholesale into the greenhouse and sooty mould covered the poor tomatoes.
For most conservatories, climbers will be the most useful plants. Floor space is usually limited and few modern conservatories have proper greenhouse borders (though passion flowers do much better when planted in borders than they do in pots). Stephanotis seems to do well and is evergreen – a huge advantage in a conservatory. If it was perfect the white, waxy flowers would come in winter rather than summer, for there is plenty else to be sniffing at between May and October. Plants will grow to three metres or more, so you need to train them and tie them in as they grow. This is not a Mediterranean plant and needs a winter temperature of around 10C/50F.
The primrose jasmine (J. mesnyi) is also evergreen and has semi-double flowers, much bigger than our winter jasmine. They bloom from March until May. It needs hard pruning when the display is over. Cut out all the branches that have flowered and tie the new growths in to wires or some other kind of support. This is something you need to bear in mind when you are thinking about where to put plants in a conservatory. All climbers look better if they are properly trained rather than bundled into a lump and hitched over the nearest projection. The best time to fit supports for wires is when the conservatory is being built.
Correct watering is also critical. Plants growing in pots do well standing on trays spread with a thick layer of clay aggregate pebbles. These absorb moisture and keep the atmosphere around growing plants suitably humid. It also saves the plant from the perils of overwatering. This is a good way of keeping houseplants happy, too.
Palms, a great feature of Victorian conservatories, do not do so well in modern, better-lit structures. Bougainvillea is a star, but needs a big tub, 30cm across at least, to grow properly. Be brave and pull off the first flowers that show in spring. When the next batch of flowers come on in July, they will then go on for months.
Oranges and lemons grow well in tubs and are at their best in winter, when the ripening fruits hang among the waxy blossom that will eventually become next year's crop. Calamondins are particularly enchanting, hung all over with small, round, orange fruit. They never get more than about 60cm/24in tall, but need pinching back at regular intervals to keep them compact and bushy.
For the best effect, you would need a grove of citrus, a potted grove, the stubby calamondins interspersed with taller Meyer's lemons, grown as standards. Their sober, glossy foliage would cool the calamondins down. The pale fruit hanging among the leaves looks stupendous. I fancy one as a centrepiece for a Christmas dinner table. It will feed the dreams until a real conservatory comes along.
WHAT TO DO
* The white flowers of the Christmas rose ('Helleborus niger') are easily spoilt by heavy rain. Either cut the flowers and bring them inside or cover the whole plant with a cloche.
* Tender herbaceous perennials can be protected from frost with humps of chicken wire, stuffed with dry leaves, straw or bracken. Tender wall shrubs and climbers may need a similar shield.
* Continue to prune bush and standard roses. Remove dead or diseased wood first, then cut back the growth made this season as much as is necessary to maintain a well-balanced head. Make the cut next to an outward or upward facing bud so that new growth will start off in the right direction.
WHAT TO SEE
* Some extraordinary conjunctions between gardening and war are on display at The Garden Museum in London. Here are the flowers gathered and pressed by George Marr of the Machine Gun Corps in Greece in the Second World War. Here, too, is the story of the horticultural society set up at the Ruhleben internment camp from 1914-18. Internees built rock gardens and greenhouses, laid out extensive vegetable plots and ran flower shows. The exhibition continues until 5 January 2015Reuse content