Some like it hot

What You Will Need:

• Plastic shot glasses (from a supermarket). After the experiment, clean for re-use.
• Cotton balls.
• Seeds such as cabbage or lettuce.
• Water.
• Permanent marker pen to label the shot glasses.
• Plastic tweezers (optional).

Prepared trial

Each prepared shot glass should look like this.

Setting the scene

Often we need to know if one type of seed behaves differently than another. This can be important in a garden, nursery, or on a farm when seeds are being chosen for planting at various times of the year. In this experiment you will find the temperature at which a given type of seed germinates quickest.

Asking a question

This experiment will attempt to answer the question:

"Which temperature is best for germinating cabbage seeds."

But, you could try this experiment on any type of seed.

Steps for a basic fair test

1. Place a teased out cotton ball in a plastic shot glass. Try and make the top of the cotton ball flat, which makes it easier to position the seeds.
2. Label this trial shot glass 'Warm'.
3. Fill it up with water, then pour off the excess.
4. Repeat with three more shot glasses, labelling them 'Cool', 'Cold' and 'Very cold'.
   
   
5. Place 10 seeds of your chosen type evenly-spaced on top of the cotton in each of the shot glasses. See picture to the right. Tweezers are helpful for positioning the seeds.
   
6. Place the one labelled 'Warm' in a warm location in the classroom like a warm windowsill or in a hot water cylinder cupboard, 'Cool' in a cool position like a cupboard in a store room, 'Cold' in a fridge (usually 4º C), and 'Very cold' in a freezer (usually -18º C).
7. Place a flat piece of plastic or cardboard over each shot glass to keep the moisture in.
8. Check them daily and record the number that have germinated in each location.
9. Which one begins to germinate first? Make a data table and graph your results. Hint: One of your data tables might look like this.

Warm conditions

Questions

• If you wanted to grow this vegetable as a crop in your garden or on your farm, what soil temperature would you sow them into for best germination results?
• How can you make this experiment more precise temperature-wise?

Going further

Can you use a similar experimental design to find what types of vegetable seeds germinate best in cool, early springtime soil conditions, say at 10 degrees Celsius?

Other related experiments

Five seed race

Germination trials