When to plant Larkspur in Arid Australia

Arid zone — applies to Alice Springs, Mildura, Broken Hill, Kalgoorlie, Port Augusta and similar areas. Growing elsewhere? Temperate · Cool · Subtropical · Tropical.

Sow larkspur direct from March to August, scattering the fine seed barely 3 mm deep into cool autumn and winter soil. This cool-season sowing is essential in arid gardens, because larkspur seed germinates best in the cold and needs the whole cool period to grow before flowering, taking around 140 days to bloom. Thin or space seedlings 30–40 cm apart in rows 30–40 cm across. A hardy annual, larkspur tolerates the frosty nights of Broken Hill and Mildura and rewards a winter sowing with tall spires of blue, pink and white flowers in spring.

Sowing calendar — arid zone

Green months are your sowing window: March to August.

Growing notes

Larkspur is a cool-season annual that must be sown where it is to grow, since it dislikes root disturbance. Direct-sow the seed thinly in autumn or winter, covering it only lightly at 3 mm, and be patient through germination, which takes 10–21 days and prefers cold soil. In arid gardens this winter growth habit is a gift: the plants do their work in the mild months and flower before the fierce heat arrives.

The common failure mode is poor or patchy germination from sowing too warm or too deep. Larkspur seed actually needs a spell of cold to break dormancy, so early-autumn heat can leave you with bare patches. The fix is to hold off until soil has genuinely cooled, and some gardeners chill the seed in the fridge for a week or two before sowing. Sow a little thickly and thin to 30–40 cm to allow for gaps.

Give larkspur full sun, free-draining soil and steady moisture through winter and spring, mulching to hold water in the dry desert air. The tall flower spikes may need light staking in windy inland gardens around Port Augusta. A word of caution: all parts of larkspur are toxic if eaten, so keep it away from grazing animals and wash your hands after handling.

Larkspur at a glance

Common questions

when to sow larkspur seeds in arid climates

Direct-sow from March to August into cool soil, since larkspur germinates best in cold conditions and needs the whole cool season to grow. Sowing in autumn heat gives poor results. The plants then flower in spring before the extreme summer heat.

why won't my larkspur seeds germinate

Larkspur seed needs cold to break dormancy, so sowing while soil is still warm often fails. Wait until the ground has genuinely cooled, and consider chilling the seed in the fridge for a week or two first. Sow only 3 mm deep, as the seed also prefers darkness.

can you transplant larkspur seedlings

It is best avoided, because larkspur resents root disturbance and often sulks or bolts after transplanting. Direct-sow where the plants are to flower and thin to 30–40 cm apart. This is why the crop is sown direct rather than raised in trays.

is larkspur poisonous

Yes, all parts of larkspur are toxic if eaten, so keep it away from children and grazing animals. Wash your hands after handling the plant, particularly the seed. It is grown strictly as an ornamental cut flower, not for any edible use.

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