SEED PROPAGATION

Learn How to grow plants from Seed

This course assumes general foundation knowledge of plant propagation. For those with industry or significant amateur experience, the course may contain some sections that are little more than revision, but for anyone with minimal or no knowledge of seed propagation, some additional reading may be required in parts in order to gain optimum benefit from the course.

The two main methods of seedling propagation are:

The direct sowing method is the best approach (if possible), as it produces stronger seedlings and a much stronger natural root system. The advantage of direct sowing is that the natural root system:

The broadcast method requires the 'pricking out' of seedlings. This method can create problems such as constricted or coiled root systems that can result in J-rooting (curled roots in the planting hole) causing instability (wind-throw), and stress caused by transplanting, resulting in poor or uneven growth. 

Lesson Structure

There are 9 lessons in this course:

1. Introduction - scope, open ground propagation, controlled environment propagation
2. Seed Botany - anatomy and physiology, pollination, hybridisation, genetic purity, etc.
3. Seed Sources - selection, collection, timing, wild collecting
4. Seed Storage - treatments; cleaning, drying, storage, disease control, germination testing
5. Dormancy - and breaking dormancy
6. Germinating Annuals, Perennials and Vegetables
7. Propagating selected Woody Species
8. Direct Seeding - grasses, woody species, revegetation projects, etc.
9. Seedling Management

Aims

• Discuss the nature and scope of commercial seed propagation.
• Explain the botanical characteristics of seed and the processes that occur when a seed germinates.
• Determine appropriate procedures for harvesting different seeds in different situations.
• Determine appropriate treatments for different types of seeds following harvest in order to sustain viability.
• Determine appropriate treatments for breaking dormancy in order to initiate germination with a range of different seeds.
• Determine how to sow and germinate seed of commonly grown herbaceous plants including vegetables, annuals and perennials.
• Determine appropriate propagation techniques for a range of woody plants including trees, shrubs, ground covers and climbers.
• Determine propagation and plant establishment strategies for developing a variety of different types of plantings through direct seeding onto sites where germinated plants will remain permanently in the position where the seed germinates.
• Manage germinated seedlings as they develop in a way that will optimise the survival rate.

SEED PROPAGATION CAN BE COMPLICATED

Every plant species has it's own peculiar features that affects the way it's seed forms, develops, germinates and grows to produce a new plant.

It is important to understand the plant you are propagating; and what needs to be done in order to grow it both appropriately and successfully from seed.

As an example; consider Banksias.

Banksia seed is encased in a hard woody fruit that rarely opens to release seed except in extreme heat, such as a fire. This characteristic protects seeds from being eaten by insects or other animals until plant regeneration is needed. After a fire, seed tends to be released dispersed and will germinate in large quantities. Many though not all species have lignotubers that will sprout foliage and regenerate a damaged plant after a fire.
  
The seed is large and winged and released from cone like fruits, usually after application of heat. In the wild, seed will be released in large amounts after a fire (B. marginata and B. integrifolia are exceptions to this rule). Cones may not open naturally for many years, even though seed could be viable inside.

Even though the flowers spikes are large and crowded with flowers only very few flowers develop fruit (seed) – in some species the flowers spike will often not produce seed at all. Therefore the quantity of seed obtained per kilogram of fruits is much less than many other plants, and this fact makes the seed relatively expensive to acquire (in terms of cost or time). A wide range of Banksia seed may be purchased from Australian Native seed merchants.

• Collect seed cones when seed is ripe, but before seed drops (for some varieties this is easy, for others, there is a relatively short period when seed can be collected). 
  Seed remains viable longer if stored in cones (but cones can be prone to insect attack and may need to be treated with a pesticide). 
  
  
• Store seed cones in a cool place. When ready to plant, place cones in a warm place for them to open and release seed. If seed does not release easily, soak the cone in water for 2 days then place in a warm place immediately. 
  
  
• Seed should be sown into sterile propagating media (eg. 75% coarse sand and 25% peat), then covered with up to 0.5cm of the same media.
  
  
• For most Banksias, germination will occur if maximum day temperatures are around 18 to 25 degrees Celsius. Some have lower or higher optimum temperatures for germination. For example B. coccinea germinates best at 15 degrees Celsius. B. aculeata germinates best at 25 degrees Celsius.
  
  
• They are best left in a pot of seed raising mix in the open or an unheated greenhouse (do not place in a heated greenhouse). 
  
  
• Damping off diseases can be a problem during early growth, and should be closely watched. To minimize risk of damping off disease, seed is sometimes drenched with a fungicide before planting. The type of fungicide used can vary from place to place, according to what is available. Look for fungicides that are listed as being effective on damping off fungi such as Pythium and Phytopthera. 
  
  
• Germination may commonly take between 3 weeks to 3 months. This period of time may be reduced for some species by treating seed with smoke. Note: Smoke treatment involves extracting chemicals that are created when vegetation around Banksias burns; then applying those chemicals to the seed. (see below)
  
  
• For most species, growth is best following germination, at temperatures around 23 to 26 degrees Celsius.

How to Treat Banksia Seed with Smoke

This treatment was developed at Kings Park Botanic Gardens in Perth. The gardens have at times sold “smoke water” which can be applied to thew seed.  You might also create smoke water by burning plant material that is indigenous to areas which the Banksia comes from; collecting the smoke and bubbling the smoky air through water. The chemicals from the smoke are then captured in the water