How Plants Grow
From the discussion on the parts of a plant, you should have an idea of what plants need to grow. The following experiments should demonstrate two of the basic needs of plants. The first of these experiments are best done in the summer while the second can be done anytime during the year.
Materials:
- 1 small to medium sized bougainvillea plant (potted)
- 1 piece black construction paper
- 4 pieces of illustration board (second largest size)
- Scotch tape
- 1 white carnation
- 2 colors food coloring
- 2 glass jars
- Water
Instructions:
1. For the first experiment arrange your illustration board into a box like structure with four walls. Make sure the white sides of the board are facing outwards.
2. Put your illustration board on the patio, garden, or area of your home that gets a lot of sunlight. Place your potted plant on one side of the box.
3. Cover the top of the plant with black construction paper by attaching the paper onto the tops of the illustration boards, making a sort of roof over your plant. Make sure that the construction paper only covers the side of the box where the plant is. The other half of your box should be open to sunlight.
4. Your end result will be a plant that is well shaded from the sun and surrounded by black paper.
5. Keep your plant under these conditions for about two weeks. Remember to water the plant every three or four days, but never let it leave the covering provided by the paper and box.
6. For the second experiment, take the two glass jars and fill them halfway with water.
7. Take your food coloring and assign one color per jar. Drop food coloring into each jar until you get a nice bright color. For example, if you chose red and blue, do not stop until you get a deep red or a deep blue.
8. Take your carnation and split the stem halfway up to where the flower is. If you are unsure, measure your carnation stem. If it is ten inches long, split the stem five inches upwards. Remember you want to split the stem down the middle (meaning both stems are still connected to the flower) not cut it in half.
9. Place your glass jars side by side. Put your flower into the glass jars by putting one stem half into one jar and the other stem half into the other.
10. Do not touch the flower for two days then see what happens.
In the first experiment, at the end of two weeks, you should notice that the plant would have started to grow sideways. Its stems are oriented towards the direction of the sun light or where the open part of the box is. On the side of the plant closer to the sunlight, the leaves may be greener and healthier looking. If there are flowers present, they are likely to be on the side closest to the sun as well. This experiment was a demonstration of how plants need sunlight, and actually look for sunlight by growing towards it.
The second experiment, on the other hand, shows you how plants take in water. If you look at the split stems of the carnation, you will see that the inside of one stem is bluish while the other stem is reddish. This is because the plant had been sucking the colored water and the food coloring left traces of dye in the plant. What's more noticeable however is that your flower will have changed color! Depending on how well you split the stems, it may be reddish, bluish, or a combination of the two making purple!
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