Seed propagation techniques and pre-treatments to break dormancy.

Updated: Jul 6

When deciding to grow plants from seeds, it is important to know the correct techniques to get your seeds to germinate, many beginners are under the assumption that you pop a seed in some soil and magically it will grow. Sometimes it can be as easy as that but often, you need to break the seeds dormancy to get it to germinate quicker and in some cases, at all.

It is all trial and error but luckily for all of us, there is much information out there regarding seed propagation and to do so effectively, it just takes a little bit of research.


We offer propagation notes on all the species that we supply, these can be found on our website under the how to grow tab. I have also recently added some external links to provide more detailed information by other industry professionals.


I like to have as much information on how to do something before I do it, I may be a little weird but I read reference books for fun, I have a huge library of the old fashioned way of reading - books, but the internet is such a valuable resource that should be used to its full potential so don't ever stop reading!


There are so many factors to consider when growing plants from seeds, the following information has been compiled from my own experiences as well as my growing Bible - Growing Australian Native Plants from Seed by Murray Ralph. This books is such a great reference tool and I would recommend others to read it, it goes into so much detail and is easy to read and understand, for a novice or an advanced grower.





Seed Viability

When we have collected or bought seeds that we intend to sell, we will check viability (and we only purchase from reliable and trusted sources - this is very important).

We will either do a cut test for the larger seeds or a full germination test to check percentage of viable seeds.


Seed Dormancy

This acts to delay seed germination until the conditions are favourable eg. fire, rain. Dormancy can vary in seeds from one year to the next due to seasonal differences and local conditions.


Types of Dormancy

  • Seedcoat or fruit physically restricts germination

  • After-ripening periods

  • Chemical inhibitors

  • Multiple dormancy factors

Seed Pre-treaments


Pre-germination

This can be done by placing seeds in a plastic zip lock bag or a container with moist sand, vermiculite or paper towel. When the root begins to emerge, transfer seed toa pot or directly plant into the garden position desired.


Hot Water Treament

This is usually the best method for hard coated seeds. Use just boiled water and pour over seeds and leave for 8 - 12 hours, seeds ready to be sowed should swell before sowing so repeat process if necessary.


Soaking and Washing

This is used to leach chemical inhibitors from the seeds eg. salt.

Soak seeds in water for 8 - 12 hours changing every 3 - 4 hours, to wash the seeds, just place under running water and rub for 15 - 30 minutes.

Washing seeds with diluted detergents for seeds containing a sticky outer coating.


Temperature

Some species will only germinate at specific temperature ranges, unless you can provide these artificially, these species should be sown at the time of year that has the required temperatures.


Smoke Treatments

This can improve results for a wide range of Australian natives but with others this can also inhibit germination. Smoke treatment can be performed in a number of ways, outlined below.


Smoked Water

Commercial water products are available from a number of sources. Depending on which species, seeds are soaked in a diluted smoked water solution at 10 - 20% for 3 - 36 hours and them sown and watered as per usual.


Direct Smoking of Seeds

This is where naked seeds or trays of sown seeds have smoke directly applied to them, seeds are usually treated for 1 hour then for the 6 - 10 days afterwards, water sparingly to prevent leaching of the smoke producing chemicals from the seed raising media.


Smoke Infused Materials

Vermiculite, sand or clay particles can be infused with smoke then placed over the seeds when they are sown. Moisten material and place in a large sieve and suspend over a smoky fire for 15 - 30 minutes.


Instant Smoke- Plus Seed Primer (SISP)

These are absorbent filters that are infused with smoke and other natural germination stimulants eg. Gibberellic Acid.


Heat Treatments

These are usually used to overcome hard, waxy or slightly woody seed coats.


Hot or Boiled Water (Wet Heat)

Usually using water at temperatures between 70 - 100 degrees Celcius, pour 4 - 5 times the volume of seed and soak for 4 - 12 hours. This treatment can be repeated several times if necessary until the seeds have swollen.


Dry Heat

This is less commonly used than wet heat for species that have poor results with other heat treatments. Acacia and Pea flowered species respond to temperatures of 80 - 100 degrees Celcium with treatment times ranging from 1 - 120 minutes.

Some species in Covulvulaceae, Germinaceae, Cyperaceae and Juncaceae have greatly increased germination if seed is heated to 60 - 70 degrees Celcius for 30 minutes.

Mix seed with sand or seed raising media, spread to a thickness of 1 - 2cm in metal trays then heat for the required time. Check the media to be sure that it reaches and maintains the recommended temperature with a thermometer.


Scorching

A light scorching where seed is put into a wire sieve then passed over an open flame a few times.


Cold Storage

Some species require exposure to cold conditions before they will germinate. Depending on the species, store seed at 1 - 5 degrees Celcius for 2 - 8 weeks.

Seed is sown as usual in trays and placed in the bottom of the refrigerator for the required time, check regularly and moisten if dry.

Another method is to put the seed in a container, add twice the amount of water to the volume of seed, then place into the refrigerator. After 48 hours drain the water then place back into the refrigerator for the time required, seeds should stay moist during the treatment. Sow seed as per usual once the treatment is complete.


Nicking or Removing Part or all of the Seedcoat

The treatment chosen is dependant on the dormancy that is within each particular species, the quantity of seed needed to treat and also the value of the seed being treated.


Nicking / Chipping / Filing

Use a razor blade, scalpel or hand file, remove/cut no more that 1mm square of the seed coat until the white part underneath is exposed but be careful not to damage the white part.

Seeds that have been successfully treated will swell in water.

This is quite time consuming so its suitable for small amounts or valuable seed lots.


Abrasion

Seed is put between two sheets of sandpaper and gently abraded, this scratches the seed coat and allows water to penetrate easier.


Cracking or Removing of Outer Seedcoat

Some thick coated seedcoats or fruits require the removal of the outer casing using a vice, sharp knife or scalpel.


Bog or Wetland Methods

Usually works best for many aquatic or wetland species because it mimics the environment that they are usually found growing in.

Sit trays or pots of sown seed are placed in another tray or container that will hold water , different species require differing degrees of waterlogging outlined below.

Some species have best results in very low levels of oxygen - this is where the water level is just below the soil surface, often referred to as the raised bog method.

Others need higher levels of oxygen so water is maintained so water is maintained at 2 - 3cm below the seeds and usually placed in full sun .


Bog or Wetland Method

Species that grow under the water should be sown in shallow water 4 - 5cm deep, best to use warm and clear water and when changing the water it should be with water of a similar temperature. Seedlings are then gradually moved into deeper water as they grow.


Chemical Treatments

These require strict safety precautions and are not commonly used.

These chemicals work by corroding hard or thick seed coats and should only be used if you know the process.

Sulphuric Acid is most effective, but others like Calcium Hypochlorite, Hydrochloric Acid, Sodium Hydroxide, Hydrogen Peroxide, Ethyl Alcohol and Nitric Acid.

Many chemicals can be used to overcoe after-ripening periods, mostly widely used is te hormone Gibberellic Acid.

Potassium Nitrate is used sometimes in place of Gibberellic Acid but is not as effective.


Natural Weathering

This can give best results for some species that are difficult to grow from seeds and done by sowing seeds by using soil and humus from where the seed was found. Trays are placed in an open position without supplementary watering - this can often take a year or more to germinate.


Digestion

Some species have better germination once they have been digested by animals eg. seeds from droppings of animals can often germinate better than those that have not.


Light / Darkness

Some species' germination is better with the presence of light, seed of these species should be surface sown or only covered very lightly when sown. This is common is small seeded species that don't have the food reserves to push through a thick soil layer.

The opposite of that, some larger seed species may respond to darkness to ensure they don't germinate too near the soil surface where soil moisture can be low.


I hope that you find some information here that can help you understand more about seed germination and pre-treatment techniques. It is always important to do your own research to find the best ways to get your seeds to germinate.

At Living Green and Feeling Seedy we are always trying new techniques in propagating seeds but it must be said that your own environmental conditions play a major part in the germination process.

We all have failures when growing seeds (yes even us!) but if we do our homework we learn new ways to overcome the problem that we may have had the last time.

Remember that not all seeds that you buy from anywhere will grow in your climate, some plants like humidity, some hate humidity, some hate cold conditions and others hate hot conditions.

Don't give up when you have failures, we sure don't!


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