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Gardening in December

Summer days and holidays …

The transition from late spring to early summer is often blurred. It’s not unusual for some parts of the country to have already experienced extreme heat well, before the official start of the new season. We know summer is really here when the hydrangeas are covered in big, blousy heads of blooms! This month, it’s all about making sure the garden is looking good.

Pink and purple hydrangeas


The hard yards put in over spring should now be paying dividends with the lawn lush and green, veggie patch producing tasty fresh crops, fruit trees showing evidence of luscious fruits ahead and the flower garden bursting with colour. At least, that’s the dream! Sometimes circumstances conspire against us, and there’s a last-minute rush to get chores done in time for the festive season and following holidays.

What to plant now: 

Now that the weather is likely to be quite hot and many parts of the country also have very dry summers, planting into the garden is not recommended. There may be some tropical edibles that could be planted in the “dry season” in the north, including sweet potatoes, yams and okra. Planting in other areas should be confined to pots and hanging planters to decorate outdoor living spaces. 

  • Seasonal flowers:

Use advanced colour or bloomer pots or shrubby plants with trailing stems to plant up large tubs and voluptuous hanging baskets. Choose from: petunias, calibrachoas, impatiens, geraniums, fuchsias.

Advanced colour flowers handing from baskets


  • Herbs:

“Soft” herbs – parsley, basil, coriander, chives, tarragon – will do better in pots over Summer, where they can be moved out of the sun and watered frequently if necessary.

  • Salad greens: 

Leafy salad favourites, especially the “pick and come again” lettuces, can be planted out provided they are watered in well and given some shade until they’ve settled in.

The Vegetable Patch:

Harvest now:

Many of the veggies planted or sown in through spring may start cropping during the month, some earlier than others. Pick what you need daily and rinse in clean water to remove dirt and dust before eating. Beans, lettuce, tomatoes, beetroot, spring onions, snap peas, silver beet and sweet corn all taste better fresh from the garden.

Three fresh tomatoes on the vine
What to plant now:

Seedlings of summer favourites and Asian greens may still be planted now into well prepared and fertilised soil. Add a long-term or slow release fertiliser and mix through the soil then moisten well a few days before planting.

Advanced tomato seedlings can still go in provided they are given some protection from scorching sun until they are established. Staggering the plantings over many weeks will provide continuous cropping throughout summer. Check your local garden centre to see what other veggies are on offer.

Plant seedlings of the following:   
  • Asian greens
  • Beetroot
  • Lettuce
  • Silver beet
  • Spring/Green onion
  • Tomato
Veggie patch tips for December:
  • Use a liquid fertiliser for vegetables and herbs such as Osmocote Boost+Feed Vegetables, Tomatoes & Herbs or a certified organic fertiliser to keep veggies growing well.
  • Check the ties on bush tomatoes to ensure they are not too tight.
  • Train climbing crops like peas and beans up tripods or trellising to keep plants up off the ground.

Peas up a tripods keeping off the ground


  • Hand pull or hoe out weeds as they appear – they compete for nutrients and moisture and may also harbour pests that could attack your crops. 
  • Water early in the day direct on to the soil – avoid wetting leaves because this could encourage diseases.
  • Build a shade cloth or bird netting cover over the entire veggie patch to prevent birds or possums eating the produce before it’s ripe enough to pick. Use a mesh size of 5mm or less to prevent birds and animals being caught in it.

Fruit & Flower Beds:

Fruits to harvest now:

The first of the stone fruits – cherries – ripen early in December. The first box into the wholesale markets is usually auctioned off for a handsome sum, donated to charity. Later in the month, apricots will be ripe, followed by early season plums.

Fresh cherries hanging off a vine


Strawberries and early cropping varieties of raspberries and blackberries all fruit in December, and the first of the passionfruit may turn purple and drop to the ground. Tropical fruits and citrus are still cropping in warmer areas, and honeydew melon, watermelon and cantaloupe are still in season in hot, dry regions.

What fruit to plant:

Planting of evergreen and potted deciduous fruit trees is not recommended over summer. Soil and air temperatures are too high and may damage roots and soft growth, from which the plants may never fully recover.

What flowers to plant:

Continue planting gladiolus corms every two weeks until mid-December. They usually flower in about 60 days. 

Beautiful pink flowers
Plant seedlings of the following into pots, tubs or baskets (not into the garden):
  • Bedding begonia
  • Candytuft
  • Carnation
  • Celosia
  • Geum
  • Linaria
  • Nasturtium
  • Petunia
  • Portulaca
  • Salvia
  • Scabiosa
  • Sweet William
  • Verbena
  • Wallflower
  • Zinnia 
Garden jobs for the month:

Summer is all about mulching – add a layer about 100mm deep of pea straw, lucerne or sugarcane mulch over garden beds, including the vegetable patch, to keep the soil cool, moist and weed-free.

Three red roses in a garden bed


  • Keep flowering annuals, vegetables and herbs growing well with regular applications of Osmocote Boost+Feed All Plant Types.
  • Continue regularly trimming evergreen trees and shrubs to keep them neat.
  • Apply fungicide sprays on fruit trees to combat fungal diseases like brown rot and freckle until fruits are almost ripe. DO NOT spray within two weeks of harvest.
  • Spring bulbs that have completely died down may be lifted now. Leave them on the grass to dry off for a day or so before gently brushing off loose soil. Then spread them out in a single layer on a wire or plastic mesh tray and store in a cool, airy and dry place until autumn.
  • Buy a couple of pots of brilliant red poinsettias a week or two before Christmas. There’s nothing quite like them to bring a real festive air to your home.
  • Take down hanging baskets on hot, windy days and move them as well as outdoor pots to a shady, sheltered spot where they won’t get burned to a crisp.

Red poinsettias


Indoor Plants:

  • Keep the air around indoor plants humid by regularly misting plants with a water atomiser.
  • Wipe leaves occasionally with a damp cloth to keep them clean.
  • If you are going away over the festive season, water all your potted plants thoroughly a day or so before leaving then move them all to the coolest part of the house. They will survive quite well for a couple of weeks without further water.
  • Feed fortnightly with ready to use Osmocote Pour+Feed Indoor Plants – no mixing required. There are also Pour+Feed products for orchids and cacti.

Lady spraying her indoor plants



Regular mowing will keep existing lawns looking neat. Raise the cutting height to leave the grass longer to protect the crowns and runners of grasses from the sun. This also helps keep the soil and roots cooler. If it doesn’t rain, water the lawn deeply at least once a week (if there are no restrictions in place) early in the morning before sunrise. 

Two children running under a sprinkler


Pest Control:

Discoloured pumpkin in the ground


  • Slugs and snails can be active whenever there are young plants around – Defender Snail & Slug Pellets in a bait trap will protect your plants and keep your pets safe.
  • Watch for aphids and other sap-sucking pests like thrips on young plants and flowers. Defender Pyrethrum Insect Spray will control them. Don’t forget to spray the undersides of leaves as well as the top surface.
  • Check for powdery mildew on roses and other plants including pumpkins and zucchinis, especially when nights are warm and humid. Use a copper-based fungicide to control them.
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