Natural inspiration: The best Christmas decorations are picked from the garden

"And here's one I made earlier," used to be a classic refrain on Blue Peter. Whenever a particularly messy and time-consuming project was under way, out came the well-worn phrase. It got the presenters very neatly from stage one straight to the finishing post, without any of the intermediate muddles and cursing that usually attend such things.

At our house, Christmas is, as ever, a little late this year. Oh for that unseen army of slaves that sticks and sprays television presenters' Christmas gifts, that chops Delia's onions and double-digs the Berryfield borders while Gardeners' World is on its winter break. Right now, I could do with a biddable gang of elves, armed with paint spray cans.

I like decorating the house for Christmas (though loathe taking the decorations down) and with chicken wire, ivy and a can of silver paint, transformation scenes are not difficult to arrange. The greatest ally is silver spray paint. You can turn putrid old necklaces into glittering tree decorations by spraying them with paint and sprinkling them, while they are still tacky, with frosting from a tube.

If you are running out of Christmas wrapping paper, you can decorate sheets of coloured tissue paper by using a template cut in the shape of a Christmas tree or a star. Worn out, no longer luminous Glowstars are ideal. Lay the template at regular intervals on the tissue paper and in short sharp bursts, blast silver paint at it. The shape – star, Christmas tree, whatever – will stay clear, the paint fading out around it. One of the most useful purchases I ever made is a pack of tissue paper (144 sheets in six different colours), £20 from Cox & Cox (0870 442 4787 or coxandcox.co.uk).

Silver paint also transforms simple greenery such as ivy, which is tough enough to stand the 12 days of Christmas without shrivelling. If you are careful, you can lever long strands of it from walls or tree trunks. Add some pieces with berries (they make ivy particularly beautiful at this time of the year). Spread the ivy out on newspaper and spray it on both sides. It does not matter if some bits escape the treatment. Use the ivy bunched in long trails to make swags hanging down either side of a fireplace. Bows of red or tartan ribbon tied round the top of the bunches domesticate the ivy sufficiently for any sitting room.

Shorter pieces of ivy are useful for decorating the tops of mantelpieces. A few large baubles set among them look suitably sumptuous. It is one way to use up baubles that have lost their hanging loops. You can also make orange Christingles to set along the mantelshelf in front of the ivy. Choose big oranges; if they will not stand upright, jam them in place with a piece of Blu-Tack or Plasticine. Carve out a small hole at the top of each orange and stick a red candle into it. Ones measuring 4-5ins are best. Fix some coloured ribbon (or tinsel) round the middle of each orange. The candles will last the course of a Christmas dinner. The oranges will last a week, after which they begin to sag and rot in a disquieting way.

An essential part of Christmas decorating is some kind of garland to hang on the door. Good Christmas garlands, like patchwork cushions, depend on having to hand a jackdaw collection of bits and pieces – in this case scraps of tinsel, baubles, bits of ribbon that are too small for tying a parcel, dried flowers that have seen better days, a few stray nuts or berries. I raid our 'Kiftsgate' rose, covered now in airy sprays of bright red hips. It's one of the best roses for winter effect.

Before you start tinkering with add-ons though, you need a garland base. The kind of shop that sells relentlessly ethnic baskets often has plain garlands made of some sort of creeper. If you want to be 100 per cent homegrown, make your own base by twisting vine prunings round in a circle. Sprayed silver, red or gold, these vine/creeper garlands make excellent starting points. Invest in a bundle of florists' wires to fix decorations to the garlands. Twist bright ribbon round it, if you like, before attaching silver-sprayed teazel heads, chestnuts, fake holly berries if you cannot find the real thing. Our trees were stripped of berries by mid-November which is why 'Kiftsgate' is so useful.

Sometimes the lower branches of a Christmas tree have to be cut off before it will fit into its allotted space. These branches of greenery will also make the base of a garland. Use green string or twists of florists' wire at intervals to lash the branches together, laying them so that the needles all point in the same direction. You may find it easier to use a solid wire ring as an underpinning and tie the branches on to that.

You can also decorate your green garlands with spray-painted bows. Scrim – the very loosely woven cloth, thinner than sacking, that upholsterers use on chair seats – makes excellent filigree bows. Cut straight strips about three inches wide and glue down a rough narrow hem on the two long edges. Tie lengths of the scrim into bows, whatever size you want, finishing the hanging ends with neat swallowtails. Spray the bows. Before they dry, plump them up so they look fat and swirling. If they are not stiff when they have dried, spray them again.

Fir cones have long been used by grand decorators as the ultimate Christmas accessory. There are many things you can do with a fir cone, though some are better left alone. A fir cone, like an ivy leaf, has been blessed with a naturally fine form, so whatever you do to it must enhance rather than obscure this. But if you have a good supply of cones of different sizes, you can make a fir cone Christmas tree.

For the base, make a wigwam of six or eight canes, about 25cms long, tied together at the top and held out in a circle by a ring of stiffish wire round the bottom. Using the biggest cones round the bottom and the smallest cones at the top, fix the cones to the canes with florists' wire, working from the bottom upwards. Place them so that each cone touches the next, making a solid, slim pyramid. At the top you can fix a small cherub, or some bells or whatever has been spurned from the proper Christmas tree.

Fir cones can also be wired on to lengths of thin rope (hardware stores are a good source of supply) to make decorations to loop round the walls. They are rather dour on their own but can easily be leavened with other things that have more sparkle. Do not use real fruit or berries in this decoration. If they rot they will stain the walls in a very unfestive way.

I didn't mention oasis in my list of Christmas necessities. Once you start using oases, you are in danger of taking the whole decorating business far too seriously. Before you know it, you will be giving your creations names: "Santa's Sleigh Bells", "Ikebana Ice" or "Reindeer Eyes".

However, for those prepared to take the risk, there is a handy oasis cone about 25cms high which can quickly be transformed into a fake Christmas tree, ideal for a table centre. Use small-leaved greenery, such as box or yew, cutting short sections of stem to push into the cone. Build it up from the bottom and include small wired baubles and trimmed down strands of silver rain.

The last task for the Christmas decorator is one of the most important. Tot up all that you have saved by making your own decorations. Then swathed in the righteous glow that this arithmetic produces, go out immediately and spend your savings on festive booze. You'll need it. Happy Christmas.