Sample Lab Report
The Effect of Water on Germination and Plant Growth in Marigolds
Question: How does the amount of water given to a plant affect how much it
grows?
Hypothesis: If I give water to a marigold seed then it will germinate and the
plant will grow more than a seed not given water.
Independent Variable (IV): the amount of water given a seed/plant
Dependent Variable (DV): the amount of plant growth
Control Group: The group of plants given water
Experimental Group: The group of plants given no water
Constants: amount of sunlight, the amount of soil, the temperature, the amount of
fertilizer, the size of the pot, the type of plant, the number of plants, the age of
the plants.
Materials:
 20 plant seeds (marigolds)
 20 - 3” pots
 Masking tape
 Pen/Marker
 Potting soil
 Measuring cups/spoons
 Plant fertilizer
 Spoon
 Water
Procedure:
1. Gather materials.
2. Using tape and pen, label each pot 1-20.
3. 1-10 pots are the Control group and 11-20 pots are the Experimental group.
4. Place 1 cup of soil in each pot.
5. Place 1 tsp of fertilizer in each pot.
6. Using spoon, mix fertilizer in soil until evenly distributed.
7. Make small indentation in soil, approximately 2 cm deep.
8. Place one seed in each indentation in pot.
9. Lightly cover over seed with soil from pot.
10. Add 20 ml of water to 25 pots labeled “Control”. Do NOT add any water to
25 pots labeled “Experimental”.
Sample Lab Report
11.
12.
13.
14.
Place all pots on windowsill.
Make data table for data.
Everyday at the same time record observations of plants/growth.
Everyday at the same time add 20 ml of water to 25 pots labeled “Control”.
Do NOT add any water to 25 pots labeled “Experimental”
15. After 14 days, measure the height of each plant and record in data table.
16. After 14 days, average the growth for each group of plants (Control and
Experimental).
17. Graph results.
18. Draw conclusions.
19. Write formal lab report.
20. Clean up and put away all materials.
Observations and Data:
Observations:
Day 1 – no growth
Day 2 – no growth
Day 3 – 5 of 10 control plants and 1 of 10 experimental plants showed growth.
Day 4 – 6 of 10 control plants and 1 of 10 experimental plants showed growth.
Control group plants are growing faster than Experimental group.
Day 5 – 7 of 10 control plants and 2 of 10 experimental plants showed growth.
Running short of time and spilled a little of the water given to plant 7 in the control
group today, not much though.
Day 6 – 8 of 10 control plants and 2 of 10 experimental plants showed growth.
Day 7 – 8 of 10 control plants and 2 of 10 experimental plants showed growth.
Day 8 – 8 of 10 control plants and 3 of 10 experimental plants showed growth.
Day 9 – 8 of 10 control plants and 3 of 10 experimental plants showed growth.
Day 10 – No more plants have germinated. The control group plants look greener
than the experimental group.
Day 11 – The control group plants look greener than the experimental group.
Day 12 – The control group plants look greener than the experimental group. Plant
#14 doesn’t look like it has grown recently and is turning brown.
Day 13 – The control group plants look greener than the experimental group. Plant
# 13 is browner today than yesterday.
Day 14 – The control group plants look greener than the experimental group. Only
Plant #17 of the experimental group still has some green on it.
Sample Lab Report
Data Table:
Day 1
Day 14
Avg.
Growth
1
0
6.4
2
0
0
3
0
7.8
Plant growth (cm)
Control Group
4
5
6
7 8 9
10
0
0
0
0 0 0
0
5.5 4.9 6.3 2.9 0 4.8 5.1
5.5 cm
11
0
0
12
0
0
Experimental Group
13 14 15 16 17 18
0
0
0
0
0
0
1.2 .7 0
0 1.8 0
.37 cm
Results:
As the amount of water given to the plants increases the amount of plant growth
increases.
Graph:
The effect of water on plant growth
6
5
4
3
2
1
No water
20 ml of water/day
Conclusion:
My hypothesis, if I give water to a marigold seed then it will germinate and
the plant will grow more than a seed not given water, was supported. The specific
evidence for this conclusion is only three seeds in the group without water
germinated and grew, but eight out of ten germinated and grew in the group with
water. The average growth for the group of plants given water was 5.5 cm while
the average growth for the group of plants not given water was .37 cm. A certain
amount of water is required for seeds to germinate. The water is needed for
chemical reactions to happen; almost all chemical reactions require water. Water is
also required for plant growth because it is a raw material for photosynthesis,
which is the process by which a plant makes its own food. Without water
photosynthesis cannot happen and the plant will not have energy to perform the
many chemical reactions that keep it alive and help it grow.
19
0
0
20
0
0
Sample Lab Report
Nine of the seeds planted did not germinate at all: two in the control group
and seven in the experimental group. I was not as surprised that some seeds did
not germinate from the experimental group because of the importance of water
during seed germination, but was surprised that two from the control group did not
germinate. Since there might have been something wrong with some of the seeds I
could improve my experiment by running another trial with more seeds (a larger
sample size) in each group. Maybe 50 seeds per group would eliminate some of the
differences in seeds and make my results more accurate. I could also improve my
experiment by clarifying my written directions so that they are easier to
understand by someone wanting to repeat my experiment. I had one source of
error in my experiment. On day 5 I was in a hurry and spilled a little of the water
that was supposed to be given to plant 7 in the control group. This means the plant
did not get all the water is was supposed to and that fact might have reduced, even
a little bit, the growth of the plant.
I think it would be interesting to run another experiment where I find out
how much water is necessary for a marigold seed to germinate. Based on this
experiment, in some cases there is enough moisture in the soil to allow for
germination. So, I would have to dry the potting soil for all plants to control for
that. My hypothesis would be, “If I give a minimum of 5 mL of water to a marigold
seed each day then it will germinate”. The independent variable would be the
amount of water and the dependent variable would be whether germination
occurred or not. Another experiment I could conduct would be to see what amount
of water is the ideal (best) amount for maximum marigold plant growth in 14 days.
This experiment would be similar to the one I ran previously, but this time all
groups would get different amounts of water to see which amount produces
maximum growth. The independent variable would be the amount of water and the
dependent variable would be the amount of plant growth.