Plants can be grown at home from either seeds or cuttings.
Whether you choose seeds or cuttings will depend on the particular species of plant you want to grow. We’ve listed some advantages and disadvantages of each method.
Seeds
Advantages:
- Many species of plants are easily grown from seeds with no special treatment.
- Plants grown from seed have greater genetic diversity– this is more ecologically valuable (i.e. better if you are planting a large number of the same species) as it means a more robust population of plants, able to withstand a wider range of conditions, diseases and pests.
Disadvantages:
- Collecting and preparing seeds for propagation requires a bit of dedication as it can be very time-consuming.
- A percentage of seeds from most plants may naturally be unviable, so germination rates may be lower.
- Some seeds have natural dormancy which is broken by specific environmental conditions (e.g. fire) so you might need to treat the seeds before planting.
For further information on this method, visit collecting native seeds
Cuttings
Advantages:
- Some seeds can be very difficult to grow as the mechanism that breaks their dormancy is unknown – the only way to grow these plants is from cuttings
- Can produce offspring that are genetically identical to the parent (clones) – good if you have a favourite plant that grows well.
Disadvantages:
- Genetically identical plants aren’t so good for revegetation of large areas since genetic diversity is what keeps plant populations resilient and able to bounce back from disaster and disease
- Many plants are unable to self-pollinate – this means that if you have only genetically identical plants of a species, they may not be able to produce seed.
Choice of soil
The seed raising medium you use is an important factor in your propagation success. It should be fine, but not so fine that it gets waterlogged and doesn’t drain properly. Seed raising mix combined with coarse river sand is generally a good blend. You can also mix in some perlite which aerates the soil and helps it to stay moist. For small seeds, use a plastic tray with plenty of drainage holes. Larger seeds and cuttings may be planted straight into their own small pots.
Collecting seeds
The method used to collect seeds from a particular plant depends on the type of seeds and seed casings the plant has.
Further details are available on under collecting native seeds.
Germinating seeds
Plant your seeds into the mix, not too deep – smaller seeds like eucalypts don’t even need to be covered. Water well, and keep the seed raising medium moist (but not wet) at all times. It’s also best to keep the seeds in a warm place and secured from hungry scavengers if possible.
The time taken for the seed to sprout depends on the species. Most will sprout within a few weeks, but some particularly difficult species can take up to 12 months to poke their heads above the soil.
The first leaves that appear are usually the ‘seed leaves’ or cotyledons. The next leaves are the true leaves, and these can look quite different from both the seed leaves and the adult leaves of the plant.
When your seedlings have sprouted two full pairs of leaves, they are ready to be planted into their own pots. The best pots to use are deep and square, with ribs running down the insides. The ribs are important as they encourage the roots to grow straight down. Ordinary round pots will lead the roots to curve around the sides of the pot and in on themselves, strangling the plant in a process known as root girdling.
For further information on this method, visit collecting native seeds
How to gather cuttings
Depending on the plant species, a stem or green branch can make a good cutting. The cutting should contain at least three nodes (the buds that produce leaves) and be cut just below a node. Remove between one and two thirds of the leaves on the cutting and cut remaining leaves in half to reduce water loss. Take care not to let cuttings dry out before they are planted – put them upright in water as soon as possible.
The older the cutting is, the more likely it will be to need some help to grow roots. Consider applying a rooting hormone product to the base. Then simply plant each cutting into its own small pot in a good quality potting mix.
Planting on
Plants are ready to go into the ground or into larger pots once a few roots have emerged from the bottom of the pots. The timing of this stage again depends on the species. If you leave seedlings in the small pots for too long they can become root-bound, which stunts their growth and also stops the roots from branching and spreading when the plant is planted on.
If your plants have led a relatively sheltered existence to this point, for example in a greenhouse, it might help to harden them up a bit before planting them in the big wide world. Place them in their pots in the sunlight for a few hours each day leading up to when you plant them, but do not let them dry out. Keep the soil moist but not wet throughout the process.
Collecting native seeds
Native plants display a wide variety of built-in seed dispersal mechanisms to ensure the seeds travel away from the parent plant and don’t just fall to the ground underneath.
Seed collectors therefore face a bit of a challenge – getting to the seeds before they disperse too far.
Different types of native seeds
Woody capsules
(e.g. eucalyptus, melaleuca, hakea)
The seeds of plants such as eucalyptus, melaleuca and hakea species are contained inside woody fruits which may remain on the plant for several years before they open.
Collect ripe capsules that are still tightly closed, and place in a paper bag or newspaper-lined tray in a warm spot – as the capsules dry out they will gradually open, releasing the seeds.
Cones
(e.g. casuarina, banksia)
Banksia and casuarina fruits are woody and have lots of individual compartments, some with seeds inside and some without. Parrots are masters of extracting seeds from cones – get to them before the parrots eat them all! Collect the whole fruiting body, making sure that the seed capsules are still tightly closed.
Casuarina seeds may be extracted using the ‘paper bag’ method described above, but Banksia cones may require more heat to split the capsules open. This can be achieved simply by baking the cones in a slow oven (100°C) for about 20 minutes. Watch them closely and you will see the capsules open before your eyes.
Seed pods
(e.g. acacia, daviesia, hovea)
Seed pods are often hard and difficult to break open while the seeds are ripening, but when they are dried out enough, they become brittle and eventually snap open with such force that the seeds are flung away from the parent plant.
Acacia seed pods look like flattened beans, and split open along the seams – on a hot, quiet day you might even hear them snapping open. Tie an old stocking or cloth bag around the ripe seed pods while they are still on the plant. This will catch the seeds as they are released.
Fleshy fruits
(e.g. figs, lilly-pilly)
Many rainforest plants produce fleshy fruits that are appetising to a range of birds and mammals. These animals are key aids in the dispersal of their seeds, which are unaffected by the process of digestion and will start germinating wherever they are deposited. Some seeds even require the acidic environment of a digestive system to dissolve the outer seed coating and break their dormancy.
Collect whole ripe fruits from the tree and around the base. Under running water, clean away the pulp by rubbing the fruit through a sieve fine enough to trap the seeds. Only do this right before you plan to plant them though, and do not let the seeds dry out.
Wind dispersed seeds
(e.g. paper daisy, grasses)
Seeds from some plants develop feathery tops so that they can be whisked away from the parent plant by even the slightest breeze.
You can pick these straight from the plant when they look like they’re just about to blow away.
A few restrictions
A seed collection is much more ecologically valuable if it is made up of seeds from a number of different plants of the same species. There are, however, specific guidelines to follow when venturing beyond your own backyard to collect seeds.
You can collect seed from most species on your own land without a permit. Before collecting seed from anywhere else, including Council land, you will need to gain the permission of the landholder and you may require a permit. Learn more about seed collecting restrictions by visitng the Queensland Government website.
There are restrictions on collecting seed from threatened or protected species – in the Redlands these include grass trees (Xanthorrhoea species), Christmas Bells (Blandfordia grandiflora), Cabbage Palms (Livistona australis), Bottle and Flame trees (Brachychiton species), cycads and orchids.
Maintaining your seed collection
Cleaning seeds
Once you’ve extracted your seeds from their respective casings, they may be mixed in with all kinds of not-so-useful materials (such as infertile seeds and parts of the seed capsules) collectively known as ‘chaff’. Some of the chaff can be blown away as it is lighter than the seeds. Larger pieces may be removed using a fine tea-strainer that will let the seeds through but trap the waste material (or vice versa).
Storing seeds
Once you have collected your seeds, conditions may not be favourable for you to plant them straight away. With a bit of care, you will be able to keep them viable for many years.
Before storing seeds, they should be dry and free from any insects. You can spray them with fly spray or place a mothball in the container with them for a short time, but this isn’t recommended long term as it can affect the seeds’ viability. Then simply pop them in an airtight jar or snap-lock plastic bag in the fridge.
Breaking dormancy
Many seeds aren’t quite ready to germinate when they leave their parent plants. They lie dormant under the ground, sometimes for several years, until subjected to the specific triggers they need to begin germination. Fortunately for the home gardener, many of these natural triggers can be simulated. It’s best to apply these treatments just before you plant the seeds.
Simulating bushfire
The Australian bush is spectacularly good at regenerating after fire, thanks to many plants that have seed designed specifically to survive the extremes of a bushfire.
Wattle (Acacia species) seeds have very hard seed coats which can be cracked open by heat. Pour near-boiling water over the seeds and let them cool – the combination of heat and water will help split their hard seed coats. Only plant the seeds that swell up in the water, as this indicates the seed coat has been cracked and it will therefore be more likely to germinate.
Others like Boronia need specific chemicals in bushfire smoke to trigger germination – the fiddly smoking process is made easier by commercially available ‘smoke water’ which has had smoke bubbled through it and can be used to soak seeds.
Scarifying
Scratching or scarifying the seed coats of certain hard seeds such as wattles and peas might increase your success rates. If the seeds are large enough, use a sharp knife or scalpel to scratch each seed. If they are smaller, rub them with sandpaper – the easiest way to do this is to line a plastic container and its lid with sandpaper, then put the seeds in and give it a good shake.
Leaching
Seeds such as Melicope species need to be soaked in water or leached with running water to remove chemical barriers to germination. An easy way to do this is to put them in a stocking inside your toilet cistern! You can also place them in a jar of water and change the water at regular intervals.
No special treatment/dormancy
Seeds from plants like bottlebrushes, paper daisies and eucalypts don’t need to be treated at all – they can be planted straight into seed raising mix.
Stop wet seeds from clumping together
If your seeds are wet from cleaning or treatments and you want to plant them straight away, mix them with some vermiculite before sprinkling over the seed raising mix.
Vermiculite is a lightweight mineral which will stop the wet seeds from clumping together, ensuring the seedlings will be more evenly dispersed.
It will also increase the water holding capacity of the soil.
More information
For more information, contact IndigiScapes on (07) 3824 8611.