Variation in seed size, shape and hardness should be considered when deciding on depth of sowing and how the seed is treated before sowing, in order to maximise germination.

While many seed varieties germinate rapidly when sown, others have a dormancy period, caused by physical (hard seed coat), chemical (inhibitors) or temperature sensitive (vernalisation or fire) barriers. Simple techniques have been developed to break these barriers. Physical barriers may be overcome by damaging the hard seed coat to allow water access into the seed, for example, by cutting the seed coat with a sharp tool, rubbing with an abrasive material, or immersion in boiling water, or for large seeds, such as macadamia nuts, cracking in a vice. The inhibitors providing chemical barriers are mostly in the soft flesh surrounding the seed. Removal of the flesh and thorough washing is generally enough to promote germination. Some flesh is pasty and very adhesive and may require soaking in a warm-water bath until it is dissolved. Seed from species in areas with seasonal cold or fire periods often have temperature sensitive barriers. Dormancy is probably controlled by chemical or physical barriers which are destroyed when subject to extreme cold (stone and pome fruit, etc.), or dry heat (many Australian native species of Banksia, Acacia and Eucalyptus).

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