Seed pretreatment of hard-seeded species (Scarification)

Examples: Broom, gorse, false-acacia, laburnum, tree lupin

Tropical legume trees - Acacia species, Leucaena leucocephala

Overview

All these seeds possess a thick, impermeable seed-coat which prevents or significantly retards germination. Pretreatment consists of removing, puncturing, abrading, splitting, burning or softening the hard seed-coat - without damaging the embryo within. These are the only tree seeds which do not need to be moist to respond to pretreatment.

Pretreatment methods before sowing

Chipping

Photo illustrating chipping

Hold seed down with an eraser. Use sharp knife / scalpel to chip away small section of seed coat without cutting embryo. Wear safety spectacles.

Boiling / hot water

Photo illustrating softening with boiling/hot water

Pour 3 to 10 volumes of boiling / hot water on 1 volume of seeds. Allow seeds and water to cool for 18-24 hours.

Abrasion

Photo illustrating abrading

Use abrasive paper to remove a small section of the seed-coat.

Burning

Photo illustrating burning

Make a small hole in the seedcoat with a soldering iron or a hot instrument taken from a fire.