When to plant Horseradish in Subtropical Australia

Subtropical zone — applies to Brisbane, Gold Coast, Sunshine Coast, Coffs Harbour, Lismore and similar areas. Growing elsewhere? Temperate · Cool · Tropical · Arid.

Plant horseradish direct in April, September or October, setting root crowns or seed pieces deep at 50–80 mm into loosened soil. Roots and any seed are slow to break, taking around 14–21 days to show, and the crop needs a long run of 140–180 days before the pungent taproots are worth digging. Space plants 30–60 cm apart with rows about 60 cm wide to give the roots room. In Sunshine Coast and Lismore gardens the autumn and early-spring plantings sidestep the worst summer heat, letting the plant bulk up through milder weather before you harvest in the cooler months.

Sowing calendar — subtropical zone

Green months are your sowing window: April and September to October.

Growing notes

Horseradish is tough and hardy, and in the subtropics its main problem is that it is almost too vigorous. Give it a deep, well-dug bed in full sun to part shade, work in plenty of compost, and keep the water up through the growing season for fat, tender roots rather than woody, fibrous ones.

The classic mistake is planting it loose in a mixed bed and losing the whole garden to it. Every scrap of root left behind resprouts, so horseradish spreads relentlessly and is genuinely hard to remove. Grow it in a dedicated corner, a large bottomless pot sunk in the ground, or a contained bed you are happy to keep to it. Come harvest, lift the entire plant and sift the soil for stray root pieces.

In a humid Brisbane summer the leaves can attract chewing pests and the odd fungal spot, but the plant shrugs most of this off and the roots are unaffected. Dig roots from late autumn into winter when the cool weather concentrates their heat; flavour is sharpest after the plant has been chilled. Store lifted roots in damp sand or the crisper, and grate only what you need since the pungency fades fast once cut. Grown near Potato, tradition holds it deters potato beetle, though trial evidence for that is limited.

Horseradish at a glance

Companion planting

Grows well with

Potato: Traditional claim: deters potato beetle; limited trial evidence

Common questions

How deep do I plant horseradish?

Set the root crowns or pieces 50 to 80 mm deep into loosened, well-dug soil. Planting at an angle with the thicker end higher helps the crown shoot away. Deep, loose ground gives you longer, straighter roots.

Will horseradish take over my garden?

It can, because any root fragment left in the soil resprouts. Grow it in a contained bed, a sunken bottomless pot, or a corner you do not mind it colonising. When harvesting, dig the whole plant and remove every root piece you can find.

When is horseradish ready to harvest in the subtropics?

Give it 140 to 180 days, then lift roots from late autumn into winter. The cool weather concentrates the pungency, so flavour is strongest after a spell of cold.

Does horseradish grow well in Brisbane's humidity?

Yes, it is hardy and largely untroubled by the wet. Leaves may pick up some chewing pests or leaf spot in a humid summer, but the roots you are growing it for stay unaffected.

Keep exploring