If you are ever looking to conduct an experiment with plants but you don’t want it to take all year, try planting radish or mustard seeds. Both plants are speed demons in the plant world. Radishes can go from seed to edible radish in less than a month. If you are looking for something that flowers, plant mustard in the heat of summer and they may bolt (the farmer word for a vegetable crop flowering) within 30 days. Most radishes also bolt quickly in the heat of summer.
There are countless experiments you can try with plants, just keep in mind that you will need to control every variable except the one you are testing. Here are some variables you might encounter:
If you were conducting an experiment testing the effect of soil acidity on the growth of radish plants, you would need to control (or keep the same) all of the other variables listed above. You would want to make sure the acidity of the different soils were different but that you watered them the same, had the same light source and soil type, etc.
Think about what types of data you need to collect and set up a system for making consistent observations. You may want to measure and record plant height, number of leaves, color of leaves, how droopy or erect the stem and leaves are and any other observations you find interesting. It may help to develop a scale for rating things that you cannot measure with numbers, that will help you analyze your data with graphs and charts.
You can learn a lot about how plants grow and the scientific method by conducting experiments with plants!