Not all seed germinates easily. Some seeds have a physical or chemical inhibitor to germination designed so that the seed will only germinate in natural habitats when conditions are favourable. In some cases the inhibitor can be overcome by pre-treatment of the seed before sowing but with others, successful germination has defied all attempts.
Australian 1) and African plant species that grow on grasslands or fynbos are known to be able to postpone flowering and germination from seed after an event that cleared the area from competition. One of such events is a bushfire.
Marland Holderness, a keen photographer from Cape Town, South Africa reports:
"… not all orchids occur massed after a fire, many are quite scattered and some have only been identified from one specimen. Some orchids only bloom the first season after fire and this is why we get so excited. There should not be a fire at this location again in my lifetime."
This not only synchronizes flowering but also causes dormant seeds to be triggered into growth after waiting for a period of years up to decades 2)3). The mechanism is often based on chemical compounds in the smoke which then trickles in the soil and come into contact with the seeds, mostly via rainwater (see also banana-treatment).

There are a number of ways to emulate this natural proces:

• Create a controlled fire. Put leaflitter and twigs on your compost and let this burn for 2-3 minutes. This works best with seeds that are larger than those of terrorchids, the relatively small amount of heat is large enough to burn the orchid seeds. Use a terracotta pot, not a plastic one.
  
• Smoked Vermiculite and granules: a number of commercial sources sell smoke-infused soil ingredients. In case of vermiculite, mix it in with the top 1 cm part of the soil or sprinkle it on top of the seeds. The chemicals will leach in the soil after each watering. There are also other granules available but these have to be boiled in water in which the seeds need to be soaked for 2 or 3 hours.
  Sources: Nindethana Seed Service and The Wildflower Seed Company (PO Box 804, Canning Bridge, WA 6153, USA)
• Smoked Paper Disks: These apparently originated in South Africa. The seeds are soaked in a container containing one of the disks for 24 hours prior to sowing.
  Source: Nindethana Seed Service
• Smoke Water: A product called "Regen 2000 Smokemaster" is available, although it's not the sort of item stocked by your average garden centre and the smallest package is about 10 litres.
  Sources: see list of distributors

From the NZNOG Journal # 60: Winsome and Les McHugh wrote 4) on Western Australian growers’ methods for stimulating flowering in terrestrials. Burning pots. Pots are buried one inch below the soil surface and covered with a couple of inches of pine needles. This keeps the tubers cool and (stops them) from drying out. During February/ March the needles are burned; the pots are dug up after the first rain - close to what happens in the bush.
Fire water. Smoke from leaf litter is bubbled through water forming a soup of ash and dissolved gasses. The water is then poured onto pots. Two months after a scrub fire the area still smelled of smoke, but after a rain the smell had gone - where? Well washed into the soil of course. Could this washing in be as critical as the fire itself and are the mycorrhizal fungi stimulated?… King’s Park of Western Australia are selling fire water by the bottle (rather expensively too!)….
Bee smoker. Leaf litter smoke applied directly over tubers.
"Against all I’ve written are we trying to make them flower too much? We all would love to have big pots full of flowers each year but I think we are asking too much. Scrub burnt hot takes years to recover and years to build up enough vegetation to support another hot fire… Do we have to give orchids a break?"

ingredients





A length of chimney pipe, 2 to 3 foot long

A hair dryer

2 pieces of flexible metal tubing, both 4 feet long

a bucket of rainwater