Collecting and growing your own seeds
Growing native trees from seed offers kids a wonderful insight into what makes them so special. Germinating native seeds is not as hard as you might imagine. This is the first in a series of items on how you can incorporate features of the TfS programme into your teaching curriculum.
How does germinating seeds fit into my teaching curriculum?
Germinating seeds is a ‘one stop shop’ fulfilling the key achievement aims within the nature of science, living world and environmental education curriculum requirements. Seed germination is a great way to introduce concepts which develop from the study of life processes, ecology and evolution such as plant life cycles, plant structure, flowering, pollination, reproduction, dispersal, growth, biological diversity and interaction with each other and with the non-living environment.
But first, we need to obtain seeds and TfS suggests that you collect your seeds rather than purchasing them from a nursery. You can collect native seeds on a school field trip, or better still from trees planted in previous years on your planting days. Seeds can even be collected from the native trees in your school grounds. There are many teaching and learning opportunities to be gained when students collect the seeds themselves. For example teachers can introduce ideas about why trees produce seeds, why some seeds/fruits are coloured and some are not and what sort of distribution mechanisms plants have developed. The need for care when collecting seeds to ensure plants are not damaged is an important emphasis too.
Naturally collecting seeds is preferable to buying seeds from a local nursery since unfortunately the ecological integrity of some commercial supplies cannot be guaranteed.
Some of the issues you need to be aware of when collecting seeds are discussed below (see: What is ‘best practice’ seed collecting?).
Need some ideas? Go to the Taranaki Regional Council website for a work unit highlighting the value of trees in our environment.
What seeds are best to germinate?
Many native plant seeds germinate rapidly and do not require storage or cleaning; so seed availability will determine when you can germinate them. Only seeds which are easy to germinate have been selected for this section.
You can download a list showing when plant seeds are ready to collect and what they look like when ready. Clicking on the plant image will take you to a page about the plant which includes information on how to germinate its seeds.
What can I do with the seedlings?
Having germinated native tree seeds it is a pity not to give your students the opportunity to grow and care for the emerging seedlings. This can be time-consuming but the results make it worthwhile. Not only will your students learn about growing plants, but they can also use their growing plants to investigate and measure how environmental factors such as sunlight, water, temperature and pests affect their growth.
TfS schools have a plant growing unit (PGU) or shade house and growing seedlings is what they do. If a school doesn’t have a PGU or shade house there are a number of options available on the market from a small garden cloche to a walk-in shade house. With today’s emphasis on growing vegetables and/or participating in restoration projects schools have every reason to have one.
Students can grow their seedlings to plant out so that they can restore and revegetate at risk land just as TfS students do, or they can propagate their plants for sale later on – maybe to fund a shade house.
What is ‘best practice’ seed collecting?
If the intention is to grow seedlings and plant them out or to sell them for a profit then there are a couple of terms you should be familiar with.
Provenance: When harvesting seed from wild sources one of the most important considerations is the provenance of such seeds – the geographical location and altitude at which the seed was collected. For example plant hardiness is particularly important. Seed collected from one locality may be quite unsuited to another.
Unfortunately, some people in the nursery trade may not realize the importance of provenance and all too often produce plants that may be unsuited to particular conditions.
Ecosourcing: This involves using only those native plants that have been propagated from the species that naturally occur or grow in the area they are to be planted in. The reason for this is that
– only plants native to a particular area should be used so that the purity of the local genetic stock is not compromised
– there is no danger of introducing species that are not native to the area.
Plants sourced from those of local origin are considered to be genetically more suited to the local climate and growing conditions.
Provenance is obviously important as some plants are simply not adapted to grow in some areas or localities. Not everyone agrees with Ecosourcing but the concept is supported by most local councils. Where a planting project involves an area that contains existing native vegetation, there is probably no question that only locally sourced material should be used. However, in their enthusiasm, some people tend to adopt a purist attitude and insist that all plantings should be ecosourced.
Extracted from: METCALFE, Lawrie: The Propagation of Native Plants (Random House 2007)
Seed germination techniques
Science Kids provides some very elementary information on how to germinate seeds – using common garden varieties. Try using native seeds!
DOC recommends the following:
Fill a clean container or seed raising tray with seed raising mix to within 3 cm of the top. Press down mix. Sow seeds. Be patient – some seed take up to ten weeks or more to germinate.
Fine seeds – grasses to cabbage tree size (<2.5mm):
– Sow on surface evenly but not too thickly.
– Cover with a thin layer of seed raising mix and/or fine pumice.
– Keep damp – do not allow the tray to dry out, keep warm (20°C) and shaded until germination.
Larger seeds – from trees, bigger than cabbage tree seed (>2.5mm):
However, METCALFE, Lawrie: The Propagation of Native Plants (Random House 2007), pp28-31 gives more detail. The TfS Primary School Resource Lesson 10 provides teacher guide material.
How to grow on your germinated seeds
For seeds sown directly onto a seed raising mix they can be ‘pricked out’ once they have grown to between 5-10cm high. Consult information on ‘pricking out’ or view a short video on the TfS website.
Good luck! Back to Te Māra a Tāne