Most people in Wollongong plant natives in spring, because that is when the nurseries fill up and the weather starts to feel like gardening weather. The rain gauge disagrees. Here is the whole year, month by month, and the reasoning behind each call.
Start with the rain gauge, not the calendar
The Bureau of Meteorology holds 38 years of monthly records from the Wollongong University station, 25 metres above sea level on the coastal plain. Read those numbers in order and the planting year more or less sorts itself out.
March is the wettest month on that record at 160.4mm, with February just behind at 156.4mm. The driest is July at 63.4mm, and September is the second driest at 67.4mm. Add the three autumn months together and you get 396mm across March, April and May. The three spring months give you 283mm.
Autumn delivers roughly 40 per cent more rain than spring, and it delivers it while the air is cooling down instead of heating up. That is the entire argument for autumn planting in one sentence.
Why autumn beats spring here
Three things line up in March and April. The soil is still holding summer heat, with mean maximums of 24.5°C and 22.5°C, so roots keep growing. Air temperature is falling, so the plant is not trying to push new foliage at the same time as new roots. And the wet is arriving rather than leaving.
A native planted in March gets eight or nine months of root growth before it meets its first real heat. Plant the same shrub in October and it goes into summer on roots that are six weeks old. In our view that is the most common reason a new native dies in its first year in the Illawarra, and it has nothing to do with the plant being the wrong species.
The calendar
The gardening year here starts in March, not January. That is how we have set it out.
Autumn: the planting window
March
The wettest month on record, and the soil is still warm. This is the best month of the year to put a native in the ground in the Illawarra. Plant, water it in properly once, and let the weather do the rest. If you only do one planting session a year, do it now.
April
Still wet at 129.3mm and still mild. Planting continues. This is also the month to get mulch down across the whole garden, before the ground cools. Coarse mulch, 50 to 75mm deep, pulled back clear of stems.
May
The last of the good planting weather. Soil temperature is dropping and root growth slows with it, so anything going in now wants to be decent advanced stock rather than tube stock. Finish the mulching.
Winter: structure and pruning
June
Stop planting. This is pruning and shaping season, and the best month of the year to look at a garden honestly, because there is no soft new growth hiding the structure underneath.
July
The driest month on record and the coldest, with a mean maximum of 17.0°C. People assume winter means wet. In Wollongong it does not. Check established natives on the dry side of the house, particularly anything under eaves. Weed now, while growth is slow and roots lift cleanly.
August
Temperatures start to lift. Prune what has finished flowering. Do not cut grevilleas or callistemons back into old bare wood, because most will not reshoot from it. Tip prune young plants little and often instead, and you will never need the hard cut.
Spring: growth and feeding
September
The second driest month on record, and growth is starting. This is the month everybody wants to plant, and the month we would rather they mulched and fed. If you do plant now, understand that you are committing to hand watering through to March.
October
Warming fast. Feed natives with a low phosphorus fertiliser. This matters more than people expect: banksias, grevilleas and hakeas are genuinely sensitive to phosphorus, and a standard garden fertiliser will damage their roots.
November
Hedging and trimming. Growth is quick enough now that a hedge cut this month will have filled back in before Christmas.
Summer: hold the line
December
Top up mulch wherever it has broken down. Mulch is the difference between watering once a week and watering three times.
January
The hottest month, with a mean maximum of 25.6°C and mean minimum of 17.9°C, and 130.3mm of rain on average. Hot and humid together brings fungal problems. Keep air moving through dense shrubs and avoid watering foliage in the evening.
February
The second wettest month. Ground can be properly waterlogged, especially on escarpment clay. Do not plant into it. Wait three weeks for March.
Two corrections for where you actually live
Those figures come from one station on the coastal plain, and the Illawarra is not one climate. Two adjustments are worth making.
If you garden at the foot of the escarpment, in Keiraville, Mount Pleasant, Mount Ousley or parts of Figtree, cold air drains downhill overnight and pools at the bottom. Those gardens run colder than the coastal figures suggest, and the clay holds winter moisture long after the coast has drained. Push your planting a fortnight earlier into March, and watch for waterlogging through June and July.
If you are on the beach side, in Thirroul, Austinmer, Bulli or Towradgi, the sand drains fast and the salt wind never really stops. The rainfall totals above are not what your soil actually holds onto. Autumn planting matters more here, not less, because you are trying to get roots down before the first hot northerly of the season. We went into that split in more detail in designing for escarpment versus coastal Illawarra gardens.
Where to find plants that are actually local
Two resources worth having open when you are choosing species:
- The Growing Illawarra Natives plant finder, a searchable database of species indigenous to the region.
- Wollongong City Council's Grow Local program, which publishes a free Illawarra natives garden guide.
Both will tell you what belongs on your block. Neither will tell you when to put it in, which is the gap this calendar is meant to fill.
If you remember one thing
The best month to plant a native in Wollongong is March. The most over-rated is September. Everything else on this page is detail.
We’d like to walk the property with you.
Free on-site consultation across the Illawarra. We’ll read the soil and aspect, work out what suits your block, and put the timing in writing so you know what happens each month.