Simple ways to use smoke for better plant growth | Gardening 101 | Gardening Australia

Many Australian plants have adapted to germinate – and grow – better after being exposed to fire. Millie shows some simple ways to harness the power of smoke water. Subscribe 🔔 http://ab.co/GA-subscribe

Indigenous people have known for thousands of years how fire stimulates mass germination of wildflowers and other plant growth, and cool-burns with plenty of white smoke are still a key way to regenerate country.

In 1995, scientists in WA pin-pointed the group of chemicals in smoke that help seed germinate – they named them karrikins from ”karrik’ meaning ‘smoke’ in the local Noongar language.

Some plants won’t germinate without karrikins, while for many others smoke chemicals improve germination rates and produce healthier seedlings.

Millie shows some simple ways to harness the power of smoke water and other treatments.

In nature, these chemicals are present in ash after a fire and are then washed down by rain to reach the dormant seeds in the ground. You can mimic this in the garden by putting a thin layer of leaves and twigs on the surface of a tray of seed-raising mix, setting fire to it, then sowing your seed and watering it in.

You can also use smoke-infused water or vermiculite to stimulate germination and, while both are available in shops, they’re quite fun to make at home.

Never leave fire unattended; always check local conditions in your area beforehand and never light fires on days of total fire ban.

What you need:
– A vessel for the fire (kettle barbecue or terracotta pot with lid; lid will need hole for hose)
– A bucket with a lid
– Some hose
– Water
– Fuel for the fire
– Vermiculite
– Seed
– Vacuum cleaner with attached hose

What you do:
1. First light your fire! You want a cool, slow, smoldering burn that will last for 30-40 minutes, not a big fire.
2. Millie makes hers in a large terracotta pot that is big enough to hold a metal tray of vermiculite.
3. To make smoke water, half-fill the bucket with water. Millie uses and dust-extraction bucket that already has two hosepipe-sized holes in the lid.
4. Run the hose through one of the lid holes so the end is under the water.
5. Meanwhile, now the fire is smoking well, she puts the vermiculite tray in place and puts a smaller pot on top to act as a lid. The top pot has a drainage hole that is large enough for the hose to fit into.
6. Attach the other end of the hose from the water bucket through the hold in the smoking pot lid.
7. Now connect the vacuum to the second hole in the lid of the water pot; when you switch the vacuum on, it will suck the smoke through the water. Let it run for 30-60 minutes.
8. After an hour, the water will be smoke-coloured, full of the compounds from the fire. The vermiculite will also have absorbed the smoke.

How to use the vermiculite:
Millie adds some smoked vermiculite to some seed-raising mix and fills up a seed-raising tray.

Sow your seeds in the tray, and top with a light cover of smoked vermiculite to hold it in place. As you water the seeds, the chemicals will leach into the soil and do their work.

You can also water the seeds with diluted smoke water – Millie uses 1 cup (250ml) of smoke water in a 1-Litre container but you can dilute down to 1:10.

As well as smoke benefitting Australian native seeds from fire-prone areas, there is some research that suggests even tomato seeds benefit from smoke treatment. Why don’t you have a go?

Seeds That Benefit from Smoke Treatment:
More than 400 native species respond to smoke treatment. As well as some members of the Fabaceae (peas and acacias), Proteaceae (banksias and waratahs), and Myrtaceae families, this includes many heathland and grassland plants, such as: Flannel flowers (Actinotus spp.), Eriostemon spp., Grevillea spp., Hakea spp., Verticordias, Stylidium spp., Lechenaultia spp., Stackhousia spp., Conospermum spp., and Calytrix spp.

Sowing and smoking are best done when germination would naturally occur in your part of Australia.

Useful Links:
Smoke to Sow and Grow – WA Gov.

Filmed on Taungurung Country | Central Victoria

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