Teacher preparation

Overarching learning goal: Saving seeds with your students is a fun and rewarding activity that will enable your vegetable garden to be established, re-planted or maintained relatively cheaply and will allow students to explore the role of seeds in plant life cycles. Students will be asked to follow the life-cycle of seeds from initial observation to propagation.

Teacher content information

In this activity students will undertake six tasks:

observing plants
selecting seeds to harvest
harvesting seeds
drying, cleaning and storing seeds
propagating seeds
reporting

Seeds can be saved for use in the following year or shared with others. Seeds from annual plants are ideal to collect as they complete their life cycle (from seed to seed) in one year.  The best time to collect seed from most plants is late autumn (depending on the plant and its lifecycle), and the best time to plant is in spring or  late term 3 and early term 4 after the most severe  frosts.  There are three main parts of a typical seed:

embryo
endosperm
seed coat

 The embryo (a tiny dormant cell) contains the genetic material of the plant and can divide to form a new plant; the endosperm (or food supply) contains carbohydrates, fats and proteins that the young plant draws on as it begins to grow; and the seed coat or hull protects the seed.

Try these seeds! Some good choices for young seed savers: beans, peas, lettuce, capsicums, tomatoes, watermelon, pumpkins and squash (These last two are easily cross-pollinated by insects, so you might get unusual offspring!)

Student and classroom organisation

Step 1. Observing plants

Long before they appear, plants provide clues about the coming seeds through their flower development. Invite students to carefully observe flowers in the garden. This is best done in spring and early summer when the most number of plants will be flowering.

Ask your students:
- Where do you think seeds will be produced on each plant?
- What clues or signs of potential seed development do you notice?

As the season progresses, students may notice that flowers are drooping or withering. Ask them to explain why they think this happens and predict what will happen next. Drooping indicates that a flower's job of attracting pollinators (like bees) is done and seeds are now developing. If seeds are visible on the plants ask the students to collect a seed and draw a diagram of it and identify the three parts of a typical seed (broad bean seeds are particularly good).

Step 2. Selecting seeds to harvest

Challenge the class to identify plants they think are ready to be harvested for their seeds. Discuss as a class how students will decide from which plants to collect seeds.

Students can tie pieces of coloured wool around each chosen plant as a marker. A class inspection of these marked seeds can follow and an explanation sought as to what evidence students have for their choice. Remind students that healthy plants with good characteristics are the best from which to breed. Encourage students to think like gardeners do, by discussing which plants have qualities they value and which will have their seeds chosen for replanting. For example, does one tomato plant produce bigger or juicier fruit, and which lettuce plant seems healthy and disease-free?

Step 3. Harvesting seeds

The best time to harvest seeds is on a sunny day, once dew has evaporated, however the method used and the time of year varies from crop to crop. Tomato seeds, for example, are ready to harvest when the fruits are ready to eat, however beans should be left on the plant for weeks after you would normally eat them. A general rule of thumb for seeds in pods and capsules is to harvest them when it looks like the plant is naturally ready to drop or disperse them. Some seeds, like lettuce and dill, ripen over time so students can collect them by shaking the seed heads over a paper bag every few days.

Your students will need to devise ways of collecting seeds from different types of plants. This will vary depending with the seed type, its size and number. Collection approaches employed may include: plucking with tweezers, shaking over a paper bag or sweeping them from beneath the plant.

Step 4. Drying, cleaning and storing seeds

If seeds are relatively dry when harvested, have students place them on newspaper, paper towels, or screens in a well-ventilated spot. Leave them for about a week or until thoroughly dry.

Seeds that are moist or encased in a gelatinous sack (eg. tomatoes) need different treatment. These fruits contain chemicals that inhibit germination (so seeds don't sprout inside the fruit). Students can use a simple fermentation process to rescue the seeds:
- scoop them out along with the gel
- add water
- leave the mix in a jar for several days in a warm spot, stirring occasionally.

The viable seeds will sink to the bottom. Rinse and dry them as described above and place them on a paper towel with a pair of tweezers. Allow them to dry and then cut them out and plant them next spring, paper and all!

As a class brainstorm what the ideal storage conditions would be for each seed. Encourage students to first list the requirements for seeds to germinate (ie. water, warmth and the endosperm or seed’s food store) and then based on these requirements, identify how the seeds should be stored so they do not germinate.

Most seeds keep well in tightly sealed glass jars in the refrigerator or a cool cupboard. Students should label their seed jars to ensure they know where and when they should plant their seeds. See: Seed-Saving-Label PDF

Step 5. Propagating seeds

In spring propagate some seeds from those you have collected. Encourage students to use the label to check the seed’s preferences for shade/sun, soil type and moisture level, before they plant out their seeds.

Students may undertake simple experiments when propagating the seeds:
- Seeds may be planted in conditions similar or different to those recorded on the label. What impact does planting location have on plant growth?
- Seeds may be harvested from healthy and unhealthy plants and grown in identical conditions. What differences can be observed and how can they be explained?

Step 6. Reporting

Individually or in small groups ask students to present their understandings of the lifecycle of plants from seed to seed. Students can: create a flow chart of the life cycle of a plant, draw a cartoon storyboard or prepare a literary piece. Early finishers may be challenged to write a rap song as well.

Assessment/Reflection

The Extension/Homework activities below will provide the students with a way to reflect on the larger picture of the seeds' place and importance in our environment. Select some of these big questions for your students to investigate.

Investigate the different ways of treating seeds prior to planting. Some need to be kept in the fridge, some need to be soaked in boiling water before planting, and others need fermentation or scarifying of the seed surface. Can students suggest why?
Investigate plant adaptations – such as seed dispersal or methods of attracting pollinators. How have plants adapted and evolved to ensure their ongoing survival? - Discuss hybrid plants and why it is better not to harvest seeds from these plants.
Investigate genetically modified crops. What benefits and concerns do they present to traditional varieties of crops? How is the lifecycle of the plant modified?
Look into the number of varieties of vegetables/fruit/herbs grown 100 years ago and compare that number to the number that are grown today.
Compare the taste of a home grown tomato to the taste of a tomato bought from the supermarket. What is the difference and why?
Investigate the role of ‘seed banks’ in Australia and around the world. Start your own!
Research the record time for any seed to lay dormant and then to be successfully grown.
Research the role of seeds in plant classification by botanists.

Seed Saving

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