Q: I am emailing you to ask for your help with my science fair project in botany. My topic is “How would various temperatures affect the growth of a ‘Baby Gold’ ivy?” I was intend to take 4 of the plants and put 1 in to a hot and dry environment, 1 into a cold environment, 1 into a mild humid climate and 1 into it’s regular environment. I was going to explain the importance of having a plant in its correct environment.

A: First – you have to define only one variable for your experiment. If your topic is “How would various temperatures affect the growth of an Ivy”, you have to make sure that all other factors are the same in each of the four environments. In other words, the humidity, the light level, the soil mix and the watering must be identical in all four – – -only varying the temperature in each to gauge its effect on ivy growth.

To measure humidity you need to learn how to make a wet bulb thermometer. Your science teacher can explain how and give you the chart used to determine humidity.

How will you vary the temperature in each sample while keeping the light level identical? I’ll let you figure that out.

To measure the effect of temperature (or any other variable) on a plant I’d measure average leaf width in each of the samples and also measure the average distance between individual leaves.

You need to get started right now because it will take a few weeks for any effects to show up.

Here is a link to plans for a light stand you can use to provide identical light.