Tip: Propagation and Germination Methods - Smoke and Fire

Smoke Infusion for Seed Germination in Fire-adapted Species

Smoke: Smoke treatment often helps germination of plants from fire-prone environments, particularly Mediterranean-climate plants such as many species from California, Chile, Australia, South Africa, and the Mediterranean region. Prepare a dilute smoke solution by adding one part commercial smoke flavoring to nine parts water. Either soak the seeds in this solution overnight (or until they swell), or water the pot or flat once with this solution. Look for the "all natural" type that lists only water and natural smoke concentrate as ingredients. Smoke treatment is still experimental, and you may have to try different dilutions.

Fire: Sow in a flat or pot and cover with several inches of pine needles or heavy straw. Burn this and leave the ash and charcoal in place, and water the flat as usual.

Here is very informative link from the University of Washington, on how exactly that works:

• Explained:  Smoke Infusion for Seed Germination in Fire-adapted Species 
• Ready to go Smoked Vermiculite: Found here