Common Speargrass

From Seed

Propagation of Aciphylla squarrosa from seed is notoriously challenging and germination rates can be low and erratic. Success relies heavily on using absolutely fresh seed sown as soon as it is ripe, typically in late summer or early autumn. Seed that has been stored often enters a deep dormancy that is difficult to break.

Sow seeds on the surface of a gritty, free-draining seed raising mix. A mix of 50% pumice or grit and 50% seed compost is suitable. Cover the seeds with a thin layer of grit-just enough to anchor them but still allow some light to reach them, which can aid germination. Place the trays in a cool, sheltered environment, such as a cold frame or unheated greenhouse.

Be patient; germination can take anywhere from a few months to over a year. If no germination occurs by the following spring, subjecting the trays to a period of natural winter cold (stratification) can sometimes trigger sprouting. Once seedlings appear, grow them on in their pots for at least a year to develop a robust root system before carefully transplanting them, disturbing the roots as little as possible.

From Division

Vegetative division is generally the most practical and reliable method for propagating established clumps of Common Speargrass, although it requires physical effort and care due to the plant's formidable spines. The best time to divide plants is in early spring or autumn when the soil is moist but not waterlogged.

Lift the entire clump if possible, or carefully dig away soil from the side you wish to remove. Use a sharp, sturdy spade or knife to sever the offset from the main parent plant. Ensure that each division has a healthy section of the taproot and several growing points.

Replant the divisions immediately into prepared ground or deep pots filled with a gritty mix. Water them in well to settle the soil around the roots, but thereafter keep the watering moderate to prevent rot. Aciphylla species have thick, fleshy roots that are prone to rotting if damaged or kept too wet, so excellent drainage is critical for the survival of new divisions.

Cultivation and Care

Aciphylla squarrosa is a plant of open, exposed places and thrives in full sun. It demands a position with excellent air movement and sharp drainage. Heavy, clay-rich soils or those that remain waterlogged in winter are often fatal. In the garden, raised beds, rockeries, or scree gardens mimic its natural habitat best.

These plants are dioecious, meaning individual plants are essentially male or female. If you wish to produce viable seed, you will need to grow several plants to ensure you have both sexes present for pollination. The flower spikes are spectacular and scented, attracting a range of native insects. Once established, Common Speargrass is extremely hardy, tolerating severe frosts, strong winds, and dry spells, making it a low-maintenance structural plant for suitable climates.