Vegetable nursery

There are different ways to obtain plants with which to start our garden. For practicality and chances of success, it is very common to buy seedlings (small plants) to start crops. However, this form limits the number of different varieties that we can grow, since only seedlings of the most commercial varieties are usually found.

Another way to start crops is to use seeds purchased or obtained from our vegetables in previous years. This is the most interesting form from the didactic point of view, since it will allow us to work on germination (the process by which a seed originates a functional plant). In this activity we will know the requirements that a seed needs to be born and we will obtain the first little plants that we are going to plant in our garden.

Cycle:

• 6-12 years.

Duration:

• 2 sessions, temporarily separated.

Materials:

• Containers of yogurt or custard (one per student @).
• Plastic bottle caps (one per student or share in groups of 3-4).
• Continuous paper or recycled sheets.
• Kitchen paper napkins without drawings or color.
• Lettuce seeds (if possible, of different varieties).
• 3-4 seeds of some legume (peas, lentils, broad beans, etc.).
• Culture substrate for seedbed.
• Lunch box or two plates.

• The substrate or soil where the seeds can be planted can be bought or made by mixing equal parts of garden soil, compost (or earthworm humus) and washed sand (or peat). The resulting mixture must be sieved with a small light sieve.

• The lettuce seeds can be replaced by those of another crop that we want to introduce into the garden. The only thing that will change in the activity is the planting depth. We can consult a planting calendar for the region in which we are to know the crops that we can put to germinate according to the month.

Goals:

• Observe the germination process and the changes that occur in the seed.
• Know the requeriments for a seed to germinate.
• Produce our own plants for the garden.
• Perform scientific experiments to obtain desired information.

Development:

In this activity we will learn to sow the seeds correctly and to give the necessary care to the small plants until they can be planted in the garden. In addition, we will observe the changes that occur during the germination of the seed and we will discover through a simple experiment what the seeds need to germinate.

Session 1.

The first thing we will do is place a few tables together, in the center of the class. In the center of them the substrate for seedbeds will be placed, on a piece of continuous paper or recycled sheets. The students, each with their own recycled container to plant, will be located around these tables.

We will explain that we will use seeds to obtain small plants, which we will take care of in class until they are strong enough to take them to live in the school garden, where they will be happy with the other vegetables and the other inhabitants of the garden.

Before filling our pots with substrate, we must drill the bottom of the container (3-4 small holes) so that excess water drains, otherwise, our seedlings may not be born or may die prematurely. We must also write our name to identify our pot.

Next, we fill the pots with substrate up to the brim and settle them with a couple of soft blows on the table.

Next we will proceed to sow our lettuce seeds; for this we must bury 2-3 at the depth indicated by the seed envelope. If we do not have this information, we can always follow the general rule that they should be buried to a depth of three times the thickness of the seed. In the case of lettuce, whose seeds are very small, it is enough to place the 3 separate seeds in our pot with substrate and then add a thin layer (2-3 millimeters) of substrate on top of them.

Finally, we carry out a gentle watering using recycled bottle caps, being careful not to dig up the seeds. During the first days it is very important to keep the substrate moist, so we must water every day, but in small quantities.

Apart from the seeds sown by the students individually, we will sow the legume seeds together between sheets of moist kitchen paper to be able to observe the germination process. We can use a plate or a lunch box to place the paper with the seeds. We will keep it humid, but not flooded, covered with another plate or the lid of the lunch box, in a dark area (in a drawer they could be fine). We will explain that a small root and a small stem will emerge from the seed in a few days, which will grow and give rise to a complete adult plant. We will observe every day how germination evolves in these seeds and we will indicate that this is what is happening in the seeds that we bury.

To discover what the seed needs to germinate, we will also sow, organized into 5 groups, 5 little pots with lettuce seeds, which we will identify with an indelible marker: 1 (normal sowing with normal watering); 2 (normal sowing without watering); 3 (normal sowing and excessive watering without perforating the container; waterlogged); 4 (the seeds are not buried); 5- (the seeds are buried to the bottom). Each group will plant (and care for, if necessary) a pot.

Session 2.

When the seeds of the pots that the students sowed individually have been born, we will check what has happened with the seeds that we buried a lot (5) and those that we did not bury at all (4), compared to the seeds in the pot 1, buried at the correct depth. In the case of small seeds, such as those of lettuce or carrots, the seeds that are buried a lot do not usually appear. Seeds that are not buried may not grow either, although in some crops the seeds may germinate if we keep the surface of the substrate moist. With this comparison it will be possible to verify the importance of sowing the seeds at the appropriate depth.

Next, we will compare pot 1 with pot 2 (without watering) and pot 3 (flooded). The seeds need water to germinate, therefore, the seeds in the pot without watering (2) will not grow. In addition to water, seeds also need air (oxygen) in order to start germinating. When the soil is waterlogged, it has very little air; for this reason, we will possibly find that the seeds in pot 3, which has remained flooded, will not have germinated either. With this comparison we will be able to verify the importance of making an adequate irrigation so that germination occurs.

Optional sessions.

During the first days of the plant’s life we can follow its growth by measuring it daily, representing it by means of graphs, making a daily follow-up by means of drawings and/or writing down the main changes that occur during germination and in its first days of growth. All this, writing it down in our garden notebook.