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Gardening in May

Autumn’s final hurrah…

There can be no doubting this month that Winter is almost here! Days are shortening, nights are colder and brisk winds encourage us to rug up before heading outside. Even tropics dwellers are feeling the chill in the air, although it’s nothing like that experienced down south!

Autumn leaves


May is also “chrysanthemum month” when we celebrate Mother’s Day with bunches of extravagant blooms from this ever-popular perennial which is at its peak in late autumn.

What to plant now: 

For those living in cool to temperate areas, there’s a lull in planting now, as it’s too late for all but the hardiest of seedlings to go and still too early for deciduous trees and shrubs. The first two weeks of May, however, are ideal to get in the last of the tulip bulbs you’ve had chilling in the fridge. In warm temperate to tropical climates, now is the perfect time to get planting!

A few suggestions to get you started: 

  • Evergreen trees, shrubs and climbers: 

Australian native plants, exotic shrubs and climbers like hibiscus, tibouchina, hoya, bougainvillea, bomarea, mandevilla and pink or yellow trumpet vine (allamanda).

  • Perennials: 

Dianthus, pin cushion (scabiosa), gaura. 

  • Spring flowering bulbs: 

Tulip bulbs that have been in the fridge for a few weeks can be planted from the last week of the month.

Pink tulips


  • Seasonal flowers:

The last seedlings of pansies, violas, bellis, calendulas, cinerarias, cornflowers, polyanthus and primulas should be planted early in the month in cool areas. In warm temperate to tropical areas marigolds, impatiens, delphiniums, Iceland poppies, polyanthus, snapdragons and sweet peas will all do well.   

  • Woody and perennial herbs:

“Hard” herbs - rosemary, sage, thyme, bay laurel, oregano, mint* – may be planted now in warm climates. “Soft” herbs – parsley, basil, coriander, chives, tarragon – may be grown under cover in cooler areas or outdoors in warmer climates.

*Mint should be grown in a pot to stop it becoming invasive.

  • Winter and Spring vegetables: 

Beetroot, brassicas, peas, rhubarb and artichoke suckers in warmer areas. It’s generally too late to plant seedlings of winter veggies in southern areas.

The vegetable patch:

Harvest now:

There’s not a lot to harvest from the veggie patch now, apart from the leaves of the “pick and come again” lettuces and other greens line spinach and silver beet

What to plant now:

Certified virus-free strawberry plants and runners can be planted this month in all areas. Protect young plants from cold with a straw, lucerne or sugarcane mulch that will help keep the soil warm and weed-free.

person planting vegetables
In temperate areas, a late planting of seedlings of:
  • Silver beet
  • Broccoli
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Chinese cabbage
  • Kale (including Tuscan kale or cavallo nero)
  • Leek
  • Spinach
  • Spring onion
In warm regions, sow seeds or plant seedlings of:
  • Beetroot
  • Broccoli
  • Cabbage
  • Carrot
  • Cauliflower
  • Peas
  • Silver beet
  • Spinach
  • Soft herbs – parsley, coriander, basil
Veggie patch tips for May:
  • Keep veggie crops healthy and growing well with applications of liquid fertiliser for vegetables and herbs such as Osmocote Boost+Feed Vegetables, Tomatoes & Herbs or a certified organic fertiliser every two to three weeks.
  • Water deeply at least once a week if the weather is dry. 
  • 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.
  • Use snail and slug traps or baits to protect young seedlings.

Fruit & flower beds:

fruit hanging
Fruits to harvest now:

There may still be some crops of late season fruits maturing. These include:

  • Apples 
  • Pears 
  • Selected oranges
  • Persimmons
  • Quinces
What fruit to plant:

Evergreen fruiting plants such as passionfruit vines and citrus may still be planted in warm to tropical areas. It’s still too early for and new bare-root fruit trees. They are best planted in mid to late winter.

What flowers to plant

Spring flowering bulbs:
  • Lachenalia
  • Muscari (grape hyacinth)
  • Tulip
  • Watsonia
Winter and spring flowering annual seedlings in warm climates only:
  • Alyssum
  • Aquilegia (granny’s bonnet)
  • Cornflower
  • Dianthus
  • Gaillardia
  • Geum
  • Gypsophila
  • Impatiens
  • Iceland poppy
  • Polyanthus
  • Snapdragon
  • Viola

pink flowers


Garden jobs for the month:

  • Keep seedlings growing well with regular applications of Osmocote Boost+Feed All Plant Types.
  • Check camellia flower buds – if they are too crowded then remove some (“disbud”) to allow blooms to develop fully.
  • Clean and sharpen your garden tools, especially secateurs, loppers and pruning saws so they are ready for action in winter.
  • After dahlias and chrysanthemums have finished flowering, cut plants down to encourage new shoots, which can be taken as struck as “green cuttings” in spring.
  • Rake up fallen leaves and either add them in layers to your compost bin or spread them over garden beds, where they will breakdown to produce humus-rich leaf mould.

person hedging
Indoor Plants:
  • Plants inside the home assist in purifying the air as well as lending a touch of greenery to your living areas. 
  • Over the cooler months, make sure plants are kept out of draughts and away from heaters and air conditioners that can dry the atmosphere.
  • Your plants will thrive in temperatures and humidity levels that are most comfortable for you. If your home is heated, place a saucer or bowl of water near your plants but DO NOT stand pots in water!
  • Occasionally wipe leaves with a damp cloth (no detergents or oils, please!) to remove dust and dirt that can affect photosynthesis.
  • Keep them growing well with ready to use Osmocote Pour+Feed Indoor Plants – no mixing required.
  • Southern Australia receives most of its rainfall over winter, so check how well your lawn drains and take remedial action now. Most lawn grasses will not tolerate their roots being saturated for extended periods, particularly when it’s cold.
  • To improve drainage, aerate your lawn now even if you did it in March or April. This time, use a coring machine to remove larger plugs of soil. This not only helps oxygenate your lawn but also assists it to drain and dry out after rain. 
  • If your grassed area is small, a stout-pronged garden fork worked back and forth, in rows about 300mm apart, will achieve a similar result.

Mowing the lawn


  • If your lawn remains very wet after moderate to heavy rain, then you may need to install a drainage system. This can be done with minimum disturbance using a narrow trenching spade or machine and slotted polypiping that then connects to a sump or stormwater drain. 
  • Watch for moss in shady, moist areas of lawn. A solution of iron sulfate (30 grams in 4.5L of water) applied as a spray or with the watering will help control it. Re-apply if necessary.
  • Broadleaf weeds can be problematic even in Winter. Lawn Builder Bindii, Clover & Broadleaf hose-on, safe to use on ALL lawns, will keep them in check.
In the warmer north:  
Pest Control:
  • Keep an eye out for aphids and other insect pests, especially on herbs and vegetable and flower seedlings. Use a general garden insecticide like Defender Pyrethrum Insect Spray to control them. Don’t forget to spray the undersides of leaves too.
  • Watch for the caterpillars of the White Cabbage Butterfly on cabbage, cauliflower, broccoli and other brassicas. Pyrethrum will assist or try a cabbage dust.
  • Slugs and snails can be active over winter – Defender Snail & Slug Pellets in a bait trap will protect your plants and keep your pets safe.
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