Alan's Monthly Garden Calendar - December

Published on December 13th 2018
December is a busy month and a month of celebration. Knowing that you'll be doing a bit of partying and perhaps a little over indulging I've a few garden tips that might just compensate for this.
The first area I've focussed on is indoor plants. I know many struggle to keep them happy so do see my tips. If they keel over early in the New Year don't beat yourself up about it. After all, you wouldn't if they were cut flowers would you?
I've some tips on pruning, combating the cold and on feeding the birds too. I hope that you'll find it all helpful.

The Indoor Garden

  • These need to be kept warm and out of draughts...good for centrally heated homes. Water when the leaves start to wilt and the compost feels dry. Give them a good soak but never let them stand in water for long. Buy English grown if possible as long lorry journeys will damage them. Feed regularly with specific poinsettia liquid feed for best results.
  • Azaleas need lots of water and preferably rainwater. Cold tea once a month helps too! They will tolerate lower light and temperature levels than Poinsettia. They will also tolerate draughts. Repot into lime-free compost in the spring and keep them outside in the shade before bringing in for winter next year.
  • Water cyclamen only when the leaves begin to wilt and droop. Water from the bottom of the pot. Keep in a cool place with good light. Remove yellowing leaves and fading flowers from the base of the corm. Do this with a twist and a sharp tug holding the stem with your thumb and forefinger. This ensures that you leave no stub attached to the corm and avoids rots starting there. When buying look for plants with plenty of healthy flower buds under the leaves.

Trees, Shrubs, Roses, Etc.

  • Plant roses, fruit trees and bushes when the ground is not too wet or frozen.
  • Dormant trees and shrubs can be moved now. Minimise root disturbance of these to increase the chance of success and rapid re-establishment.
  • Consider planting a range of wildlife friendly native trees and shrubs. Many are suitable for hedges which provide nectar, food and shelter.
  • Prune out old wood to rejuvenate shrubs. Wisteria pruning can be completed now along with vines.
  • Tie spreading branches of conifers in as any snow we get will only make matters worse. Old trees prone to this are better replaced with new improved varieties. Sadly, many conifers do not go on forever!
Soil Prep
  • Fork over borders and dig some goodness back into the soil. I recommend composted green waste, spent mushroom compost or farmyard manure.
  • Try forcing cut stems of winter flowering shrubs indoors. Good subjects include Winter Sweet, Witch Hazels, Lonicera fragrantissima and Winter Beauty, Viburnum fragrans & x bodnantense Dawn, Forsythia and even Lilac.

Bits and Pieces

Cold Damage Prevention
  • Prevent freezing of water pumps in water features. Remove your pump before the onset of hard frost. Give it a good clean and check wiring so that it is ready to use again in spring. If you leave it in and running do raise it off the bottom to avoid disturbing hibernating wildlife.
  • Don’t break the ice on your pond. If frozen, leave it to thaw naturally. Smashing ice can give a big shock to fish and if there are plants in the water, oxygen levels will be adequate until it thaws naturally anyway.
  • Cover your outside tap with an insulation cover. Drain down sprinklers and hoses.
  • Check that greenhouse heaters are working properly.
Disease Prevention
  • Open the greenhouse ventilators during mild weather. That encourages good air movement which lowers humidity. Always remove dead leaves and flowers regularly as this is often where disease starts.
The Big Tidy Up
  • Check and repair fences. Better to do it now than in spring when there is just so much to do!
  • If you have a garden shed or use a corner of the garage, now might be a good time to have a good tidy up! Clean and sharpen tools ready for use in the New Year. Check any that need replacing and put them on your Christmas or birthday list!
  • Wash pots and seed trays so that they are clean and ready for the sowing to start soon.
  • Mice and rats will move inside for warmth and shelter so check greenhouses and sheds and take precautions where you have seed, vegetables and bulbs stored.

Keep it Fresh

  • All cut real Christmas trees should be kept outside for as long as you can before Christmas Day. Stand the trunk in water to ensure that the tree remains fresh. It is well worth cutting a little off the bottom of the trunk before standing it in water as the cut end often becomes ‘sealed’ (treat them like cut flowers).

Wildlife and Pets

For the Birds
  • Provide clean water for birds especially in frosty weather.
  • Feed the birds regularly so that when a cold snap comes they know where to get food easily.
  • Feed birds such as Blue, Great, Marsh and Long-tail tits with high-energy feeds like fat balls and suet treats.
  • Feed robins, blackbirds, thrushes, wrens and tits with freeze-dried mealworms.
  • Encourage a wider range of birds into your garden with niger seed. This is loved by siskins, goldfinch and greenfinch.
  • However, do clean bird feeding areas on a regular basis. Use a bird safe disinfectant to guard against bacterial and fungal diseases. This is particularly important for seed feeders since disease can be spread from beak to beak via the feeder.
They aren't all Garden Friends
  • Protect the trunks of young trees against rabbits. Use coiled plastic rabbit guards or chicken wire for this.
  • Protect vegetables from pigeons with bird netting.


  • Potted ‘prepared’ Hyacinth bulbs should be moved into warmer rooms to gradually force them into flower in time for Christmas. If they are coming on too fast move them back into the cool again.
  • Plant up Amaryllis bulbs inside. Use a soil-based compost and water very sparingly to start with. As flowers and leaves appear give more water.
  • Don’t worry if there are bulb shoots already appearing outside in the garden. They are very tough and will generally survive very low temperatures. However, bulbs in thin sided plastic pots will need to be sheltered from wind driven hard frosts. Daffodils seem to be particularly prone to this and often produce yellow leaves that look a bit as if they have been burnt.

Home Grown Food

  • Prune Raspberries, Blackberries, Loganberries and other hybrid fruits - that's if you haven’t already done so. Cut out all old stems that had fruit this year. Cut out any weak spindly shoots and tie in the strong new shoots that are left. Give them a good feed with sulphate of potash.
  • Blackcurrants, if they were not done in the summer, can be pruned now too. Cut old wood to ground level. Aim to remove up to one third of the wood from each bush. Keep a lookout for any swollen buds which are infected with big bud mite and remove them as they can spread the disease ‘Reversion Virus’.
  • Prune apples and pears to improve their shape, encourage younger growth, remove disease and to control the amount of fruit bud they have. Don’t prune fan, espalier and cordon trained trees as these should have been summer pruned.
  • Grape vines should be pruned before Christmas. If pruned later the sap will often be running and they will ‘bleed’ sap which can weaken them. Other plants where this can happen are Magnolia, Japanese maples, birch, walnuts, hornbeams, mulberries and laburnums.
Other Stuff
  • Forcing of established rhubarb crowns should be started this month. Pack with straw or 'strawy' manure and cover with a forcing pot or upturned dustbin to exclude light. It won't be long before you'll have a harvest!
  • You can still plant fruit trees and bushes right through until spring but only if the weather and ground conditions are okay - i.e. not frozen or waterlogged.
  • Get on with digging the veg patch whenever the weather allows you to. Pace yourself if not used to it! Dig in Vitax Clay Breaker to improve the structure of heavy soils. Dig in well-rotted organic matter to all areas except where you plan to sow root crops.
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