Seed Basics

• Seeds don’t live forever
• If you have planted seeds in the past and they did not grow it is probably your fault
• Some seeds require special treatments to encourage them to germinate

Seeds don’t live forever
A seed with potential to germinate is said to be viable. Some seeds remain viable for many years. Seeds of some tropical plants only stay viable for a few weeks. Corn retains good viability for just one year, beans for 10 years and tomatoes last even longer.

When buying seeds look at where and how the seed is stored and packed – cool, dry positions are best. Foiled lined packs prolong seed storage life. Check the use by date. When collecting seeds directly from plants, make sure they have reached the correct stage of ripening. Make sure what you are collecting is actually the seed of the plant! Some plants are surprisingly deceptive.

If it didn’t grow it is probably your fault
While it is possible to sometimes get a poor batch of seeds, failure of seed to germinate can often be traced back to the gardener. There is an easy way to testing the viability of seed. It is known as chitting or should that be cheating?

Count out a set number of seeds and lay them in some paper towel. Roll the paper towel up, wet it using a spray bottle, then place inside a plastic bag. Check the seed every day to look for the emergency of the first roots.

Getting Seeds To Germinate
Seeds can be sown directly into the soil or into containers. Direct sowing leaves seeds open to the element. Sowing seeds in containers gives us more control over the conditions that they are exposed to.

Seed Raising Mix
Key features - light enough for the roots to be able to push down easily. It must be able to hold sufficient moisture, but should not crust on top as this may prevent oxygen reaching the roots. Potting mix is usually too chunky and open for good seed germination. Sieved compost is fine if you can tell the difference between your seeds and any weeds that happen to germinate.

Sowing Depth/Covering/Light
Most seeds do not need light for germination (eg cyclamen), but do need it once the first seed leaves appear. For others, light is essential (eg lettuce) and too great a depth of planting will inhibit germination.

Warmth/Temperature
Seeds vary in the temperatures they require to germinate. You can often make a good guess at this by looking at the season in which the plant grows best or where the plant comes from. Winter growing annuals or vegetables germinate in cooler soil temperatures (cabbage & cineraria) whereas spring and summer growing species (salvia & capsicum) need more soil warmth.

Moisture
Sufficient moisture must be present to penetrate the testa or seed coat, but not so much that the seed rots or that the oxygen level in the soil is reduced.

Some seeds require special treatments to encourage them to germinate

Sufficient moisture must be present to penetrate the testa or seed coat. Pre-sowing treatments required by seed include:

• Soaking in hot water

Pouring boiling water over seeds and allowing them to soak overnight before sowing can help to break the seed coat and promote rapid swelling and germination of seeds (wattle, parsley).

• Treating hard coated seeds

This can involve using sandpaper, wood files or a sharp knife to break through the seed coat (eg Burdekin plum and macadamia).

• Cleaning fleshy seeds of natural chemical inhibitors

Leaving the seed to ferment in water can help any flesh on the outside of the seed to break down and help to dilute the effects of natural chemical inhibitors (eg tomatoes).

Other seed treatments may include using smoke water (especially some Western Australian native plants) and use of acid to replicate the digestion of seed that would typically take place in the gut of an animal (eg fruits of rainforest plants naturally consumed by the cassowary).

How Long Should I Wait?
A marigold may take three days. A cycad may take three months

What about nutrients?
Nutrients are not required until the plants start to grow their first pair of true leaves. At this time they should be watered with liquid or soluble fertiliser. Within a week or two of this stage they will probably be ready to potted up into larger containers.