Sowing seeds/all about trees

Transcription

1 Sowing seeds/all about trees Lesson 10: How do we sow seeds? Learning Activities 1 Whole class listens to, and watches, demonstration of seed sowing procedure BLM 20. This can be in the classroom and could be followed by students drawing up their own pictorial version of the procedure to ensure that the steps are known, or use BLM 21A and BLM 21B. You could also visit your local Nursery or have an expert visit school. 2 In small groups, students check the procedure and follow the instructions to sow their boxes of seed using either BLM 20 or their own versions. 3 In class the students make initial entries on their individual record sheets, BLM 22 as well as the Master Wall Chart - BLM A. 4 Students predict the rate of growth of the plants and how tall they will grow. Measure and record the height of the plants on a class graph each week. Teacher notes These activities could be used in a variety of orders, depending on what would suit your class the most. Resources Materials needed for seed sowing, seed sowing instructions, BLM 20, BLM 21A, BLM 21B, BLM 22, and BLM A. Variations and follow-up Provide a variety of commercial seed packets for students to compare the sowing procedures on the packets. Strike cuttings from plants in your school grounds or from home gardens take care that they aren t pest plants though!

2 Sowing seeds/all about trees Sowing seeds Materials required: seeds, potting mix, seed sowing mix (this is fine sieved potting mix, mixed with fine pumice 75% potting mix to 25% pumice there is however some variation of opinion on the best mixing rate), sieve, seed trays, (the polystyrene or plastic trays that you buy meat in from the supermarket are good) floats (to make a float cut a board the same size as the trays you plan to use and then put a handle on it), fine watering can or mister spray, labels and marker pen, suitably sized water tray. Points to be aware of: Trays should be clean wash and then soak for approximately 15 minutes in 1 part household bleach to 20 parts water. Ensure that seeds of different species are not mixed in the same box/tray sow only one species at a time. Keep boxes/trays clearly labeled as the seeds are sown label trays at the beginning of the session if possible. These last two points are particularly critical if the species look similar at seedling stage of growth e.g. kānuka and mānuka. Or - not having seeds sown into boxes at all! The best way to deal with these hazards is to break the whole process into distinct steps. 1. Address the whole class as a single group and discuss the critical points with them, demonstrate the procedure and highlight the important things to remember. 1.1 The trays - have them all find the level on the tray to which the potting mixed is filled. If using old meat trays, have one tray with a line drawn on it so students can see it, or there is sometimes a raised line near the lip of bought trays. 1.2 Discuss the potting mix how it s different from dirt from the garden; that you should ensure that there is plenty of fresh air when working with it and that it is important to wash your hands with soap and water when finished.

3 1.3 Demonstrate filling the tray, ½ fill with sterile potting mix, gently shake to fill the corners, top it up to the half way mark then level and firm down with the float. It is important not to firm down too hard or this will hinder the seedling growth. 1.4 Fill the rest of the tray with the seed sowing mix. Very gently pat this down level. Fill to the ¾ mark (1 to 1½ cm below the rim of the container). By being very careful at this stage you ensure that the seeds will all be at the same depth and therefore will all come up at about the same time and, all grow to approximately the same size. 1.5 Once the tray is filled properly it should have a label put in it with the name of the species and the date being sown written on it, it is also useful to have the student s name and classroom number on the back of the label ice-block sticks are good for this, or ice-cream lids cut into strips. Leptospermum scoparium It is best to use the botanical 22/3/04 name, as many species share common or Māori names e.g. toetoe, and so you will not be certain which particular toetoe you are growing. This can be very important when it comes to planting out; making sure that each is planted in its preferred conditions. 1.5 The tray then needs to be watered. Ensure that it is sitting on a flat surface. Underwatering is when the container is sat in a tray of water for meat containers an ice-cream container partially filled with water works well, or a roasting dish is good for trays. The water soaks up through the holes in the bottom, and by wetting in this way it encourages the roots to reach for the bottom. After soaking for approximately 10 minutes leave to drain before sowing. Using a flat board with handle, (float), to level and firm down the mix.

4 2. Break the class up into small groups to begin filling trays. A good number is between 3 and 5 children per group. Each group should have; empty trays, a float, a bag or bin of potting mix, and a bag or bin of sieved potting mix. 2.1 Roam around the groups to check as trays are being filled. It is probably best to have students fill just one tray each at this stage. This part sometimes turns into a race to see who will fill theirs first. Quality of workmanship rather than quantity is the goal in every step. Encourage the children to be their own quality control monitors. I suggest you have all the group reach this stage before commencing seed sowing, otherwise things get very difficult to keep track of. 3. Gather the children back together again while you demonstrate how to sow the seeds. In this way you ll have them all in one place for distribution as well. 3.1 When sowing, the seeds are placed on top of the mix and not pushed down. They will be covered with sand or more of the sieved mix once all the trays are sown. 3.2 Consider asking one or two students come forward to demonstrate your instructions. In that way you discuss proper technique with all the students watching. 3.3 If you are sowing seeds using shakers remind the children they need to remix the seed and sand frequently by giving their jar a good shake as the lighter seed tends to float to the top and you end up sowing all seed or all sand. Place a generous pinch of seed in the shaker then have the students count out ten big pinches of sand to mix with it and take the jar back to their group. The shaker can be a saltshaker type container. When sowing seeds it is good to develop a pattern for sowing perhaps such as below, to ensure that the tray is covered but that over sowing doesn t occur. It s a little hard to generalise, as seed varies so much in size and fertility, but in the main you should need only one to two pinches of fine seed to sow an area approximately 20cm x 15 cm. If the seeds are sown too thickly, disease is likely to occur after the seeds germinate. Have one person from each group come to you for collection of their seeds and distribution to all other members waiting with their trays. Generally one to two shakers per group are enough to share around. Distribute one species only at a time! Otherwise it can get terribly confusing! If you are sowing medium, or large sized seeds, put a container of seeds near the students, so all can easily reach. These can be placed gently on the mix, rather than scattered.

5 Once all students have sown their trays, discuss the size of the seed and then demonstrate that you only cover the seed. Small seeds should not be covered more than their own diameter, but larger seeds should be covered to a greater depth more like twice the depth of the Seed is 2mm therefore it will be covered by 4mm of sand or mix seed size. 3.8 Use a sieve (a kitchen sieve is good for this) to sprinkle the mix on top of the seed, and then gently use the float again to firm and smooth the surface. Not sowing seed too deeply is very critical to your success. This needs to be emphasised to the children. They shouldn t push the seeds in with their fingers. Use a body part (half the length of your little fingernail, as thick as your eyelash, etc.) to give them a measure by which to judge how deeply to cover the seeds. 4. As each tray is completed, make sure that they are labeled, then watered this is also fairly crucial the tray needs to be on a flat surface and the watering needs to be with a mister (a very fine spray of water), preferably pointed upwards not down at the tray you don t want to disturb the potting mix or wash all the seed to one end of the tray. If the seed is very fine then an atomizer should be used. The tray is then placed into the plant growing unit. The seed of most species does not need light to germinate, but once germinated, the tiny seedlings need gentle light, and the plant growing unit provides this. 5. Once you and your students have been through this process, you can repeat at will. It is best to sow different species alternately to be sure you get equivalent numbers of different species sown. seed testa scar tawa hīnau porokaiwhiri kahikatea mataī

6 STEP NAME: Sowing seeds/all about trees Seed Germination and Growth DATE: Date seeds were sown:... Method used (e.g. seeding into trays):.... Method of seed treatment:.... Material used to cover seed (if any):.... Date of first germination:.... WEEK (after sowing seed) No. of seedlings germinated Height of seedling Notes on after care e.g. watering