Lesson 2 culture of native plants

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Soaking in boiling water 

1. Place seed in a jar/cup/container. 

2. Pour water which has been brought to the boil over the seed. 

    Cover the seed generously. 

3. Stir gently. 

4. Leave soaking for 24 hours (Water is allowed to cool. Do not keep it boiling). 

5. Remove and discard any floating seeds after the 24 hrs (the floating seed will not usually germinate). 

6. Any seed that has not swelled (but has sunk to the bottom of the container) can be re-treated in this 


7. Sow the remaining (swollen) seed. 

Species to be treated this way include those from the genera Acacia, Hardenbergia, Cassia

Kennedya, and Hovea. A few wattles have softer seed coats and can be damaged by this treatment 

(ie. Acacia harpophylla, A. stenophylla). These types can usually be determined by pushing the coat of 

the seed with your fingernail. Soft coated Acacias should be sown without any treatment. 


Stratification (Moist chilling) 

This is a method of handling seeds, which require a period of after chilling to mature the embryo. The 

following is one method of stratification that can be used: 

  Mix seed with slightly moistened peat moss, sphagnum or vermiculite (1 part seed to two parts 


  Place the mix in a polythene bag, label and tie. It is important that you use polythene as it is much 

more permeable to oxygen than some other plastics, but will retain moisture preventing the seeds 

from drying out. The seeds can be dusted with a fungicide powder to help protect them. 

  Place the bag in the bottom of a refrigerator (not the freezer). The temperature should be in the 

range of 1 – 5 degrees C. 

  Check periodically to ensure the mix remains moist. 

  At the end of the required period remove seed and sow. 


Species that may respond to this type of treatment include those from alpine and sub-alpine regions 

such as the Mt Kosciusko area, for example, Eucalyptus regnans, E. delagatensis, E. stellulata, E. 

kybeanensis, E. nitens and E. pauciflora. Banksia canei, B. saxicola. Most require at least 3 weeks, 

while some such as Eucalyptus regnans need 6 to 10 weeks. 

This method has also been used successfully for non-alpine plants such as Anigozanthos species. 



Some seeds often germinate best after a fire has passed over them (eg. Actinotus helianthi). This 

effect can be recreated on a small scale by sowing the seeds in a fireproof container such as terracotta 

pot and covering the propagation media with a small heap of leaf litter. Ideally this litter should be 

derived from species associated with the area from which the particular seeds you have sown are 

native to. The flame should be maintained for 2-3 minutes then put out. The ash is allowed to cool, and 

the pot is watered and treated as for other seed trays. 


Smoke has been shown in recent times to enhance the seed germination of many species, in 

particular, many Australian natives from fire prone areas, such as species from the following genera: 

Calytrix, Conostylis, Dianella, Eriostemon, Geleznowia, Lechenaultia, Philotheca, Pimelea, Stylidium, 



Much of this knowledge is based on research done at Kings Park Botanic Gardens in Perth. They have 

isolated many of the individual components of smoke, with the aim of producing commercial 

preparations that can be added to water, and simply watered into trays of suitable seed to increase 

germination rates. One method they have used is to soak seeds for twelve hours in a 9:1 water:smoke 

- water solution. The smoke-water can be made by bubbling smoke through a container of water for 

around an hour and then frozen until it is needed.  


Leaching seeds 

Some seeds have a chemical inhibitor that prevents or delays germination. This can sometimes be 

removed by leaching the chemical out of the seed by placing such seeds in muslin bags or similar 

material in running water for 1-2 weeks.  




When to sow 

Some natives can be successfully germinated at anytime of the year, however most are best 

germinated during the warmer months. If you are using greenhouses or other facilities where higher 

temperatures are being maintained then you can extend the time you can readily germinate particular 

species. For many species temperatures need to reach above 20 degrees C each day. For those from 

cooler climates the daily temperature may only need to reach 15 degrees C, while for plants from 

tropical areas the daily temperatures may need to reach 25 degrees C or more.   

Seed from many of the fleshy fruited species needs to be sown as soon as possible after harvesting.  


Propagation medias  

Most native plant seeds, particularly those plants that naturally inhabit drier regions, prefer a 

propagation media that provides good drainage and aeration. Commercially prepared seed raising 

mixes are readily available from nurseries, garden supplies, etc. Alternatively you can make your own 

mix.  A simply prepared propagation mix that can be used is: 


  1 part moist, finely sieved peat moss to 3 parts of coarse washed river sand (which is commonly 

sold as propagation sand).   


  The ratio of peat to sand can be altered to suit the seed being sown for example seeds that prefer a 

little more moisture can be sown in a mix of one part peat to two parts sand. 


NOTE: Peat is becoming more and more expensive, and its harvesting causes a lot of environmental 

damage. An alternative for peat is hammered coconut fibre which is readily available.  


Another way in which the mix can be altered to suit your particular requirements is the addition of 

perlite, a product created by heating the mineral mica to a high temperature. It is light-weight, inert, and 

helps improve drainage and aeration in a growing media. 


One example of such a mix is: 


  1 part coarse washed river sand: 1 part sieved peat moss: 1 part perlite 


Avoid the use of soils where possible. These are a major source of pest and disease problems. In 

addition they often become sticky when wet, or stay waterlogged, or dry to form hard crusts. 


All media ingredients should be thoroughly mixed, and the mix ideally pre-moistened prior to use, 

ensuring all parts of the mix are moist. 


Containers for sowing seed 

Suitable containers for seed propagation should have the following properties: 

  Ideally be inert so that they don't release any toxic chemicals (some wood preservatives for 

example can be very toxic), or salts. 

  Not be made of to porous a material that results in moisture being absorbed from the propagation 

media into the walls of the container. 

  Have sufficient drainage holes to allow good drainage. 

  Be able to retain the propagation media without it washing out of the bottom (i.e. through overly 

large drainage holes). 

  Have sufficient depth to allow for good root development of the germinating seeds. 


Seed sown into trays 

Seed is commonly sown into plastic trays, for example standard size propagation trays. Other plastic 

containers such as butter or margarine containers can be used but make sure you make sufficient 

drainage holes. 

Any containers used should be thoroughly cleaned first. Wash off any dirt, debris, etc. in warm soapy 

water. Then soak them in a solution of household bleach (20ml of the concentrate to 1 litre of water). 

Wash off any disinfectant of soap with clean water.  


Sowing directly into pots 

Seed of quick germinating and growing species, and whose seed is big enough to easily handle, can 

be sown directly into small pots (commonly 50mm diameter tubes). Generally two or three seeds are 

placed in each pot, depending on how much seed you have. When the seeds are germinated the 

strongest seedling is left and the others removed. 


How to sow your seeds 

The selected container should be filled with propagation media until it is nearly full. The container can 

be lightly bumped to consolidate the mix. The surface of the mix can be levelled using a flat piece of 

wood. Firm lightly but not too hard.  Water carefully, to minimise any disturbance of the soil. Let the 

container sit for a while to allow excess water to drain.  


The seeds can then be sown evenly over the surface of the tray. Try not to waste seeds by missing the 

container, and be careful that seed doesn’t blow into, or get accidentally sown into other containers you 

may have prepared, and have standing nearby. Avoid sowing too densely as this encourages disease, 

and seedlings don’t have sufficient room to grow strongly.  


Seed can be sown directly from the hand, or out of a small containers such as a pepper pot (good for 

small seeds), mixed with fine white sand (so you can see the seeds and where you have sown the 



Once the seed is sown it should be lightly covered with fine sand, propagation mix, or fine sieved 

vermiculite. Only cover to a depth equivalent to the thickness of the seed. Make sure that the container 

is labelled showing what type of seed was sown, when it was sown, where it was collected from, etc. 


Carefully water the tray with a fine mist from above, or place the tray into another container with water 

in it so that when the seed tray is sitting on the bottom of the other container the level of water in the 

larger container is only a couple of centimetres deep.  Leave the seed tray sitting there until you see 

water rising to the top of the propagation mix. Carefully lift the tray out and place it on a bench so that 

excess water quickly drains away.   


The trays can then be placed in a suitable position, such as on a bench in a greenhouse, in a cold 

frame, in a spot covered by shade-cloth, underneath shrubs that provide filtered sunlight and light 

breezes, or in a protected position on a veranda. Make sure they are not exposed to bright, direct light 

(ideally 50-80% shade), and exposure to drying winds. Avoid placing seed trays directly on soil as this 

increases the likelihood of diseases problems.  


Also make sure moisture levels in the propagation mix are suitable. This will vary according to the 

species sown but most natives prefer a mix that is always moist, but excess water can freely drain 

away. Do not let the mix dry out. Most trays will need watering at least once a day, more on hot days. 

Water using the bottom tray method: or overhead using a fine mist. In cooler conditions reduce 

watering to prevent over-watering. 


The major cause of losses of germinating seeds and new seedlings are fungal diseases. They might 

appear as rotting stems, as small patches of dead seedlings, and as leaf spots. Good hygiene 

throughout propagation is the best way to reduce the likelihood of such diseases occurring. If you do 

see evidence of fungal problems they must be treated urgently, as they can rapidly spread. Drenching 

with a fungicide such as Benlate or Fongarid will often help (these products may not be registered for 

use in your country). Other methods are to increase ventilation around the plants, reduce watering

avoid watering later in the day, dispose of infected trays before the infection spreads, or a combination 

of these things. If you find you are repeatedly suffering from these problems then you may need to alter 

your potting mix to improve its drainage, and thoroughly drench your propagation areas with a 

disinfectant such as bleach (sodium hypochlorite) or a quaternary ammonia solution. 


Fertilising is not generally necessary, but dilute applications of liquid fertilisers can be misted onto to 

the seedlings (this can be done during normal watering) about once a week, once the seedlings 



The Bog method 

This method is often used to germinate the very fine seed produced by Callistemon, Melaleuca, 

Kunzea, and Leptospermum species. Seed of these species will usually germinate easily, but the small 

seedlings are easily damaged by overhead watering, or if the propagation mix is allowed to dry. With 

this method a seed tray is sown normally, but the seed are not covered. The tray is then stood in an 

ice-cream or similar plastic or glass container. Water is slowly added to the larger container until the 

level reaches about halfway up the side of the tray. Leave the seed tray standing in the larger 

container, and cover both trays with a large polythene bag (you might need to make a simple wire 

frame to place it over). Top up the water every day or two.  


About a month after germination remove the seed tray from the water and allow it to drain. Then treat 

the tray of seedlings as for other trays grown in the normal manner, but making sure the tray is watered 

from the bottom. If disease problems arise treat with a suitable fungicide (ie. Benlate, Fongarid) and 

remove the plastic bag.  



Also known as "pricking out" this is the transfer of the young seedling out of the seed tray into 

individual containers. 


When a seed first germinates the first leaves (actually seed-leaves not true leaves) are known as 

cotyledons. Most trees and shrubs have a pair of cotyledons (this type of plants are known as 

dicotyledons), while grasses, lilies, grass trees, orchids, and many other smaller plants only produce 

one cotyledon (these are known as monocotyledons).  


For dicotyledon types when the plant continues to grow it produces its first pair of true leaves, then a 

second pair, then a small shoot. At this stage the seedling is ready to transplant into an individual 

container.  Casuarinas, which have a different growth habit, can be pricked out when they are about 

15-20mm tall.  

Great care should be taken when pricking out seedlings. The mix can be loosened, and the seedlings 

carefully lifted up using your hand, or a flat narrow tool such as a knife, or a dibble stick.  Then gently 

pick up the individual seedling by the leaf, being careful not to squeeze it. The seedling can then be 

placed into position in a partly filled container and potting mix gently filled in around it. Try to ensure 

that roots are not twisted, or bunched up during this process. This is particularly important for plants 

that have a strong tap root system. The potting mix can be consolidated by gently tapping the pot onto 

a hard surface. The transplanted seedlings should be watered as soon as possible. 


Suitable potting mixes are best purchased from a reputable commercial supplier. A suitable fertiliser 

mix will need to be added. Alternatively a coarse washed river sand and peat or peat substitute can be 

made up at home. Generally a combination of a quick release soluble fertiliser and a slow release one 

(eg. Osmocote, Nutricote) is used. Be careful using fertilisers with more than about 2 or 3 percent 

phosphorus content as many natives are adapted to soils with low phosphorus levels (eg. Banksias, 

Hakeas, Dryandras, Grevilleas). Look for specially prepared “Native” fertilisers such as ‘Osmocote for 

Natives’. Many natives are also prone to iron deficiencies – look for pale yellow new foliage, particularly 

in members of the Proteaceae family. 


Common containers used for the first potting up are: 

50mm diameter x 75mm deep round plastic tubes: (commonly used for slower growers and fibrous 

rooted types). 

50mm diameter x 150mm deep square forestry tubes: (commonly used for quick growers with tap root 

systems (eg. Eucalypts, Acacias). 



The transplanted seedlings can be placed in a tray (or other suitable container such as a polystyrene 

fruit box), and placed in a protected position out of direct sunlight. Watering is still critical. The 

seedlings can gradually be exposed to more light as they grow and ‘harden up’.  The seedlings should 

be ready to pot up into larger containers or into the ground in 1-3 months 


Keep a close eye out for pest and disease problems, and if sighted treat with a suitable control method 

as soon as possible, 



A cutting is a piece of vegetative growth (non-sexual - not the flower or fruit) which is detached from a 

plant and treated in a way so as to stimulate it to grow roots, stems and leaves; hence producing another 

new plant.  Cutting propagation is most commonly used for shrubs, indoor plants and many herbaceous 

perennials. It is the most common method of asexual reproduction used by horticulturalists.  As a general 

rule, it is rarely used to propagate most types of trees. 


When a plant is grown from a cutting it is genetically identical to the parent plant.  This is not necessarily 

so when plants are grown from seed.  Cuttings are the most widely used technique for reproducing "true 

to type" plants. This ensures that the unique characteristics of the parent plant are passed on to the 



Cuttings can often be used to propagate plants that: 

  Don't produce viable seed, or produce seed at irregular times, 

  Have seed that is difficult to germinate 

  Have seed that is difficult to collect, for example, plants that have seed pods that burst open 

dispersing the seeds widely 

  Produce their seed at a time when seed cannot be collected, or collection would require a further trip 

to the area (often very difficult for remote areas), or can only be collected with difficulty (e.g. plants 

whose seed matures during wet seasons when access may be limited).  


Cuttings can be useful as they may avoid the problem of juvenility in the newly propagated plants.  Most 

plants grown from seeds go through a juvenile stage, in which flowering, and hence seed production 

does not occur. Some plants may take 5, 10 or even more years before they commence flowering. Once 

a plant has flowered, plants propagated from that plant by cuttings will avoid the juvenile stage and flower 

early, often within months of the cutting having struck. 


Many plants also have undesirable growth forms when they are young. These include very vigorous   

growth, thorniness, or unattractive foliage or form. By taking cuttings from adult plants these undesirable 

characteristics can be avoided. 

In some cases the juvenile form of a plant may have characteristics that are more desirable than those of 

the adult form.  


You may take cuttings from plants growing in gardens, pots, parks or in the wild; and you may 

successfully produce new plants from cuttings taken from any source; however, you will always get much 

better results if you carefully choose your source of cuttings. 

  If you know the cultivar name of the plant, you can be more certain of how to propagate it, and be 

confident of the characteristics that will be demonstrated by the new plants. 

  If you take cuttings from healthy plants; they are more likely to develop roots faster, and produce 

healthier plants quicker.  

Why cuttings? 

Despite all the difficulties that can be experienced with various techniques to propagate a plant, the 

cutting technique still remains one of the easiest and cost effective techniques to produce a number of 

new plants, whether that is for commercial or domestic production. 


The home gardener will find that cuttings are easy, time effective and cheap; the rewards in watching a 

plant produce roots and develop into a new plant encourages them to propagate even more plants, and 

share them with friends etc. 

Commercial production nurseries know the benefits of the cutting technique. Their profit and existence 

relies upon using the right technique for the right plant. Improving their techniques can increase 

production and hence increase profit. 

Growing plants by cuttings can be a very rewarding exercise, and for commercial propagators may be the 

most economically viable method for many plants.  


How to propagate a cutting 

Most cuttings are pieces of stem, often with some leaves left at the top of the stem. Some plants can be 

grown from cuttings of other tissue (eg. a piece of leaf, or section of root, or even part of a bulb, with no 

stem at all). 


Cuttings are usually planted into a mix of materials such as sand, peat moss, perlite, rockwool or 

vermiculite. Part of the tissue is usually below the surface of the mix, and some exposed above the 



The cuttings should then be kept moist and other conditions such as light, temperature, humidity and 

hygiene should be kept appropriate to the requirements of the variety of plant being grown. 


Other things that can be done to enhance development of the cutting will either speed the rate of growth 

or improve the percentage of cuttings that succeed. 

Chemical hormones may be applied to stimulate the formation of either roots, or foliage/shoot growth. 

Pesticides or disinfectants may be used to prevent diseases or pests. Heating may be used to warm the 

root zone (ie. bottom heat), to encourage faster growth of roots; or periodic misting of the foliage to cool 

the top of the plant, or prevent dehydration of the foliage. 

If you want to get the best results from your cutting propagation, you really need to pay attention to 

selecting the appropriate technique for the time of year, and type of plant you are growing. Different 

types of plant tissues have varying abilities to sprout roots and shoots and turn into a new plant. 


The ease with which particular tissue can grow as a cutting depends upon the chemical and physical 

make up of that tissue. These physical and chemical properties can be extremely variable at different 

times of the year, under different environmental conditions, and even between different varieties of the 

same plant species; let alone from one part of a plant to another. To become more and more 

successful at cutting propagation; you need to try and understand these subtle differences. In time, a 

good cutting propagator can develop an ability to make informed guesses as how to propagate a wide 

range of different plants. 


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