Eucalyptus seeds from Park Seed. The hard seed coat should be scarified by light sanding or a 24 hour soak in warm water, then the seeds are pressed onto the surface of a well-draining seed-starting mix without burying them, since they need light to germinate. Keep them warm (68 to 72°F) and evenly moist, and transplant once seedlings have several sets of true leaves. Eucalyptus trees can grow large, so space them accordingly.