Gardenwise:
What to do & not to do in your garden this month…

A monthly issue highlighting all that you need to know about your garden each month of the year. What to grow, when to plant, pruning time and loads more…

What to do & not to do in your garden in December

(Previous / Next Issue)

ALL OVER SOUTH AFRICA
It is the height of summer and your garden should be flourishing and overflowing with summer annuals and perennials in full bloom. Agapanthus, hydrangeas, fuchsias, day lilies and liliums will also be flowering, and your roses should be producing their second flush of blooms. Late fruit can be harvested as well as many vegetables and herbs.

Whether you are going away or staying at home, December can be a very busy month in the garden; so get stuck in early so that you can sit back and relax over the festive season.

IF YOU ARE GOING AWAY IN DECEMBER…
You don’t want to come back to an overgrown jungle, so do not fertilise your lawn or garden beds before you leave, or growth may be too rampant. If you are concerned about watering and have to rely on rainfall, renew the mulch in your beds to help conserve water and water deeply before you leave. Clean your garden really well, removing all weeds and spent flowers, and trim your hedges etc. If you have a vegetable garden, or fruit trees that are bearing, harvest and store as much as you can before you leave.

A well-groomed garden will leave no obvious indicators to would-be burglars that you are not at home. If possible, arrange for a family member or friend to water and mow your lawn for you, and to harvest your vegetables. Remind them to empty the post box, as an overflowing post box is a sure indicator to intruders that you are away. Just before your leave, mow your lawn for the last time, but do not be tempted to cut it too short, or it could get scorched by the sun, especially if rainfall is erratic and the days are very hot.

Group all your outdoor pot plants together in a shady spot where your watering system will reach them. If you don’t have irrigation, mulch the pots with potting soil to which water retentive granules have been added, mulch with bark chips, and water thoroughly before you leave.

Group your indoor pot plants together on a sink rack with a bidum liner or an old blanket underneath. Part of the liner is immersed into a sink of water, allowing your plants to draw water as they need it, without having them standing in water. Never allow your potted plants to stand in trays of water for long as this is sure to drown them. Alternatively, place your plants on damp newspaper in the bath. Leave the curtains or blinds open to allow the natural light to reach your plants.

You can also make your own watering bottle for indoor or outdoor container plants by punching a few tiny holes in the top of a plastic bottle, filling it with water and inverting it into the topsoil next to the plant to be watered; this allows water to slowly seep into the soil as it is required.

 
IF YOU ARE STAYING AT HOME IN DECEMBER…
… and are expecting guests, the holiday rush before Christmas can leave one over-whelmed and exhausted. So put aside time early in the month to give your garden a good clean and clip, so you will only need to tidy up a bit before your guests arrive, leaving you feeling more relaxed and able to enjoy the garden with family and friends.

Feed your beds with an organic 3:1:5 fertilisers, and if you have not done so yet, mulch your garden beds.

Deadhead roses and summer-flowering annuals regularly to ensure a continuous supply of blooms. Brighten up prominent garden beds, patios and pool areas by planting out instant colour seedlings and flowering perennials into garden beds, pots and hanging baskets. Spruce up your indoor pot plants by spraying the leaves regularly with water, this will help to keep them clean and healthy as well as increasing humidity during hot dry spells; a good foliar feed can be added to the spray occasionally.

Check your plants for scale insects, mealy bug and red spider. Splash out on a few colourful pot plants to add cheer to your indoor space this Christmas.

LAWN
If you are staying at home and want a lush green lawn, feed with a high nitrogen fertiliser. Raise the blades on your lawnmower and mow more frequently; this will produce lovely fine blades. Watch out for fungal diseases as these are more evident in warm, wet and humid weather. Brown patch causes irregular brown or dead patches; dollar spot shows as yellow patches which merge and darken with age leaving fungal cobwebs on the blades that are very visible when wet; fairy rings show as dark green rings that slowly grow larger and sometimes host clusters of slender toadstools.

HYDRANGEAS
Feed and water your hydrangeas regularly, as they are heavy feeders. To make them last longer in a vase pick them in the cool of the day and make sure that the centre flower bracts are open when you pick them. Scrape the bottom of the stems with a knife, removing the outer layer, before immersing them up to the flower heads in cold water for about 12 hours before arranging.

ROSES
When your roses have had their second flush of flowers feed them with a fertiliser that is high in nitrogen like 8:1:5, to encourage lush leaf growth and another flush of blooms at Christmas. Water deeply about twice a week during hot, dry spells; ensuring that the water gets right down to the roots of the plants. If your soil is a bit hard water won’t penetrate properly and you need to dig it over lightly and put down a good layer of mulch. Continue to spray regularly with organic fungicides and insecticides to keep pests and diseases at bay.

Floribunda roses and some Hybrid Teas produce clusters of flowers, and if you remove the centre bud, it will allow the clusters to develop stronger stems; spreading out the flowering time. Hybrid tea roses are often also disbudded, leaving only one bloom per stem; this produces very beautiful large blooms for the vase.

BULBS
If you plant Nerine bulbs now they will flower in autumn. Feed them regularly to encourage flowering; adding some wood ash to the soil will also encourage good blooms.

Make sure your Dahlias are securely staked and do not dig around them as they have surface roots. If you did not divide your bearded irises last month and they are overcrowded, you can still divide them now. Discard the rhizome which produced the flowers and replant only the young pieces.

If you stored Lilium bulbs in the fridge, you can plant them out now. To propagate Criniums, save the fleshy seeds and plant them in containers; placing them on top of the soil.Water your azaleas and camellias well now as they are forming their new buds.

PONDS
Check the water level of your ponds regularly and ensure that your water plants are not growing too thickly, blocking sunlight from reaching the bottom of the pond.

PRUNING
Prune spring flowering shrubs such as weigela and piladelphus, and climbers like jasmine and petrea, to maintain a compact shape. Cut back Santolinas and trim Lemon Verbena after flowering.

Trim your chrysanthemums lightly when they finish flowering, to encourage bushiness and divide your gazanias if they have stopped flowering. Prune and tidy up spring and early summer flowering groundcovers and perennials and mulch them thickly with compost to conserve moisture.

December is a good month to take semi-hardwood cuttings of your favourite shrubs like lavender, fuchsia, hydrangea, pentas, hypericum and pelargonium.

Semi-hardwood cuttings are taken from young growth that is just starting to harden off. These are normally side shoots which can be tugged off the plant, leaving a ‘heel’ attached to the bottom of the stem. Leave this little ‘heel’ of bark on the cutting, as it will hasten rooting. Remove all the bottom leaves from your cutting and cut all large leaves in half with a scissors. Dip the cutting into rooting powder no 2 and gently shake off any excess powder before planting it into a rooting mix like washed river sand, vermiculite or palm peat.  Water and place in a cool, bright place and mist spray daily, or tie a plastic bag over the cuttings to help conserve moisture. If the bag produces too much condensation, remove it for a while.

FLOWERING ANNUALS: SEEDLINGS AND SOWING
December is an awkward time of the year to sow flowering annuals, as many of them will be at their best just when the cold winter weather hits, so check the ‘weeks to flowering’ on the back of your seed packet before sowing. You can still sow seeds of fast growing varieties like alyssum, marigolds, cosmos, Californian poppy, candytuft, ageratum, nasturtiums, salvias and portulaca.

The nurseries are brimming with instant colour seedlings that will continue to flower for many months; these are often the better choice at this time of the year.

In cold winter regions it is already time to sow seeds of winter annuals that have a long growing season; like primula varieties, ornamental cabbages, anemones and ranunculas.

VEGETABLES
Your vegetable garden should be flourishing, so harvest regularly.

Baby potatoes will be ready to harvest once the plants have finished flowering. Loosen the soil lightly with a fork to check on their development before lifting.

If your onions are ready to harvest, lift them with a fork and shake off excess soil before laying them out to dry in a cool, well-ventilated, place. Once they are totally dry, clean them by brushing with a soft brush or cloth and store them in paper bags; or plait the leaves together in bunches and hang them up in a dry cool place, that is well ventilated.

In cooler regions December is traditionally the month when the first sowings of cauliflower, broccoli and cabbage are done.
Except for the subtropical regions, you can still sow or plant seedlings of baby marrows, gem squash, patty pans, sweet corn, Swiss chard, carrots and beetroot; sow bush beans every 3 weeks for a continual supply and runner beans every 5 weeks.

If you want to sow lettuce in the heat of summer, choose heat tolerant varieties, plant them where they are shaded during the hottest time of the day, and water very well.

Plant out the last tomato plants for this season. To hasten the ripening of tomatoes, cover well-developed clusters with a brown paper bag. For vegetables that are susceptible to blight and fungal diseases, like tomatoes, squash, pumpkins and cucumbers; water early in the morning so that the leaves are totally dry by sunset.

FRUIT
Strawberries are producing the last of their fruits and need to be fed with a liquid fertiliser once all the fruits have been harvested.

Continue spraying your late bearing fruit with an eco friendly insecticide like Eco fruit fly, for fruit fly and coddling moth. Remove any fallen fruit that may be infested with fruit fly larvae. Remove or cut back excessive water shoots.

Feed your citrus trees with an organic fertiliser; 8:1:6 or 6:1:5 are good but if you don’t have them, use 3:1:5 or 2:3:2.

Grapes need to be watered well as the fruit begins to swell.

As melons start to swell it is best to reduce watering, as too much water will result in tasteless fruit.

When your berries have finished fruiting, prune out all sickly or damaged canes; leaving only young healthy canes. Tie these young shoots to a sturdy support, and train them to grow out into a fan shape.

In sub-tropical regions you can sow paw-paw seed this month. Sow them directly into the soil (5 seeds per hole) and once they have flowered, remove all male plants; leaving only one male plant for every 6 to 8 females. Male flowers hang on long stems and female flowers are tight against the stem. Feed and water your avocados and litchis regularly.

INSECTS AND OTHER NASTY THINGS
Red spiders are most active during hot and dry weather. They inhabit the undersides of plant leaves, where it is nice and dry, and seem to prefer plants with soft leaves like roses, impatiens etc.

Visible signs are a mottled yellow look on the upper side of the leaves, a fine web over the leaves, and sometimes leaf curl. Severe infestations cause yellowing and bronzing of the leaves, followed by leaf drop. This will adversely affect flower and fruit production but will rarely kill the plant.

If you look through a magnifying glass you will see them; alternatively, pick a leaf and press it down on a sheet of white paper. If there are tiny red dots left behind on the paper, you have red spider.

To help prevent red spider, ensure that ventilation is good amongst your plants and do not over feed with nitrogen. To control them you must spray regularly, as recommended, Try Ludwig’s Rose Spider Mite, it has no adverse affect on the natural predators of red spider mite.Other organic formulations containing Canola oil, with or without garlic extract work well but can cause harm to natural mite predators. Rape or grape seed oil is also effective.

Homemade sprays for red spider: Red spider is very difficult to control and will require regular spraying.

1)  Infuse about two handfuls of chopped chives in 2 litres of water overnight. Strain well and spray thoroughly underneath the leaves.
2)  Boil one cup of sugar with one cup of water, cool and dilute with 3 litres of water. Spray thoroughly underneath the leaves.

Watch out for fungal diseases like powdery mildew and black spot, and spray your roses and other susceptible plants regularly with an organic fungicide. Add a sticker or wetting agent like G-49 or Spray & Stay to the mixture. This helps the poison to stick to the plant longer, especially during rainy weather. Watering very early in the morning will help prevent fungal diseases.

If fungal diseases persist, try spraying with compost tea made from a container filled to a third of its volume with mature compost and topped up with rainwater. Allow to soak for 1-3 days and stain through a very fine mesh strainer or a nylon stocking. Spray diluted on the affected plants.

Another anti-fungal spray is low-fat milk diluted with an equal volume of rainwater.

Gardenias are susceptible to black sooty mould; a fungus which lives on the honeydew that is secreted by aphids. The aphids are ‘farmed’ by ants for this honeydew and are also protected from their natural predators by them. Get rid of the aphids and the ants and the mould will disappear.

If chafer beetles are chewing your roses and other plants, spray regularly with Ludwigs Insect Spray. Spray in the late afternoon as these beetles hide in the soil during the day and come out at night to feed. To protect against beetle attacks: Take two handfuls of chopped comfrey leaves and 250 grams of chopped garlic. Add them to 2 litres of cold water and leave overnight. Bring the mixture to the boil and simmer for 20 minutes with the lid on. When the mixture cools down dilute it with water 1:10 (one part mixture to 10 parts water). Spray at least once a week when beetles are active.

Comfrey is rich in nitrogen, protein, potash, trace elements and minerals. It promotes healthy plants and strong cell structure. The smell of garlic repels beetles. This recipe is also used to control the cucumber beetle.

Tabasco sauce to keep flying insects at bay mix two teaspoons of Tabasco sauce with one litre of water and spray your plants. Repeat after rain.

Very hot fresh chillies can also be used.

DRY, SEMI-ARID AND CONTINENTAL REGIONS
If you want to add some colour to your garden beds for Christmas, plant portulacas, they can take the heat. Ensure that your garden is well-mulched and consider putting up a rainwater tank, especially in you live in a brak water area; as a wide variety of container plants, herbs and vegetables can be grown using rainwater.

Many summer seedlings die in brak water gardens because they require regular watering in summer, which deposits many harmful salts to the already brak soil. Other seedlings are killed by very hot winds. In these very arid regions, forget about a summer garden, dig the soil over, enrich it with lots of compost and wait until autumn to plant again.

Spring gardens are successful in these areas. If your soil is clay, dig lots of compost and washed river sand into the soil as often as you can. This prevents a hard crust forming on top that water can’t penetrate.

In cold frosty regions, slow-maturing winter flowering annuals and vegetable crops are sown in December or January.  Sow primula malacoides (fairy primrose,) Iceland poppies, pansies and violas, as well as anemone seed. It is also time to sow slow maturing perennials and biennials like foxgloves and columbine (Aquilegia), to flower next spring and summer.

Sow vegetables like beetroot, broccoli, Brussels sprouts, cabbage, cauliflower, cucumbers, beans, kohlrabi, lettuces, parsley, sweet potatoes and marrows.

SUBTROPICAL SUMMER RAINFALL REGIONS
It is too hot for all but tropical vegetables like okra, sweet potatoes, eggplants, chillies, peppers, sweet corn and green mealies.  Plant out hardy summer annuals and continue feeding your beds and lawn regularly, as rain quickly leaches out nutrients from the soil.

In sub-tropical regions you can sow paw-paw seed this month. Sow them directly into the soil (5 seeds per hole) and once they have flowered, remove all male plants; leaving only one male plant for every 6 to 8 females. Male flowers hang on long stems and female flowers are tight against the stem. Feed and water your avocados and litchis regularly.

Do not cut your lawn too short.

Spray your roses, zinnias and other plants that are susceptible to fungal diseases regularly with an organic fungicide.

Don’t forget to water and feed your orchids regularly.

Spray damp, wet areas with Margaret Roberts biological mosquito spray and make sure your gutters are clean and that there are no stagnant pools of water where larvae can breed. Plant pawpaw seeds directly into planting holes now.

WINTER RAINFALL REGIONS (MEDITERRANEAN)
Continue to sow bush beans every 3 weeks, and runner beans every 4 to 5 weeks. Sow your last tomatoes for the season, and if you want summer lettuce, select heat resistant varieties. You can still sow baby marrows, baby gem squash, patty pans, sweet corn, carrots and beetroot.

If you have a cool, sheltered spot you can start sowing seed of winter broccoli, cabbage and cauliflower into seedling trays.

Continue feeding and watering your Kikuyu and Buffalo lawns and try to water in the morning. Do not cut your lawn too short when the weather warms up; especially Buffalo lawn, as it prefers to be thick.

Watch out for lawn caterpillars; they make bare patches in the lawn.

Mulch your garden beds to keep the soil moist and cool; do this before the weather becomes very hot and dry in January and February.

SUMMER RAINFALL (TEMPERATE OR HIGHVELD REGIONS)
Continue to sow bush beans every 3 weeks, and runner beans every 4 to 5 weeks. Sow your last tomatoes for the season, and if you want summer lettuce, select heat resistant varieties. You can still sow baby marrows, baby gem squash, patty pans, sweet corn, carrots, cucumbers, kohlrabi, parsley, sweet potatoes and beetroot. If you have a cool, sheltered spot you can start sowing seed of winter broccoli, cabbage and cauliflower into seedling trays.

Sow only fast maturing summer annuals now, or plant some instant colour seedlings. Rain quickly leaches out nutrients from the soil, so continue to feed your garden beds and lawn regularly with a balanced organic fertiliser.

Rainy weather also encourages fungal growth, so watch out for mildew, rust etc; implement a preventative spraying programme for susceptible plants like roses and tomatoes.

Source:  Gardening in South Africa

(Top)