When to plant Hollyhock in Tropical Australia

Tropical zone — applies to Darwin, Cairns, Townsville, Broome, Mackay and similar areas. Growing elsewhere? Temperate · Cool · Subtropical · Arid.

Raise hollyhock seedlings from March to June, sowing into trays or pots as the dry season begins and transplanting once they are sturdy. Sow at 8 mm deep, expect germination in 6–20 days, and be patient: this biennial takes around 200–220 days to send up its tall flower spires, so it must carry through into the following season. Space transplants 30–50 cm apart with rows 45–60 cm apart, along a sunny wall or fence for support. In the tropics around Cairns and Townsville, hollyhock is a hardy but rust-prone gamble, so give it the driest, airiest position you can find.

Sowing calendar — tropical zone

Green months are your sowing window: March to June.

Growing notes

Hollyhocks are old-fashioned biennials that flower best after cool weather, so the tropics test them. Raise seedlings from March to June and transplant them into a sunny, sheltered spot with something to lean against, because the spires reach well over head height and topple in storms without support. The long 200–220 day timeline means a plant sown in the dry must survive a wet season before it flowers, which is the crux of the challenge here.

The defining failure mode is hollyhock rust. It is almost a given in humid gardens around Mackay and Broome: orange pustules erupt on the undersides of leaves, then the whole plant browns and defoliates from the ground up. You can't eliminate it, but you can slow it. Space plants generously at 30–50 cm for airflow, water only at soil level in the morning, strip and bin the lowest leaves as soon as spotting appears, and never compost infected material.

Site matters too. Full sun and free-draining soil help the foliage dry fast after rain, while a crowded or shaded position guarantees an early rust wipe-out. A position under wide eaves that keeps rain off the leaves can make the difference between a flowering spire and a bare stem.

Even with good management, expect shorter-lived, less spectacular plants than you would see down south. Let a healthy plant self-seed and you may get replacements without resowing.

Hollyhock at a glance

Common questions

Why do my hollyhock leaves have orange spots?

That is hollyhock rust, a fungal disease that thrives in humidity and is very common in tropical gardens. Space plants for airflow, water at soil level, and remove and bin affected leaves early, but expect it to be an ongoing battle here.

Can hollyhocks grow in Cairns?

They can, but they are a rust-prone gamble in the humid tropics. Give them the driest, sunniest, most open position you have, ideally where eaves keep rain off the foliage, and accept shorter-lived plants than in cooler zones.

Do hollyhocks need support?

Yes. The flower spires grow well over head height and topple in tropical storms, so plant them against a sunny wall or fence, or stake them, to keep the spikes upright as they flower.

How long do hollyhocks take to flower?

Around 200–220 days, as they are biennials that build a leafy base before spiking. In the tropics that means a plant sown in the dry season must carry through the wet before flowering, which is the main challenge.

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