Have your children ever tried to grow a plant out of a seed? Have they ever wondered how large trees grow from tiny little seedlings? Odds are they have, and if they have they'd probably be interested in finding out why these things happen. Below is a simple biology science fair idea your child can both enjoy and succeed at without the last minute, frantic help of their parents.

Soil Growth vs Hydroponic Growth

Purpose

The purpose of this experiment is to determine which method of culturing seedlings works the best. In this experiment your child will try to grow seedlings from soil, plain water and a chemical solution.

Design

Each seedling is planted in a medium and observed. All growth from root length to height is measured in millimeters over the course of this experiment. Seeds should be a minimum of three varieties and a few seeds of each should be used in each medium to ensure good data by eliminating as much as possible a bad seed from ruining the data set.

Materials List

Plastic 165 ml cups

3 varities of seeds. Herbs such as rosemary, basil and cilantro work the best and tend to be consistent in their growth.

1 bottle of liquid plant food such as Miracle Gro

1 bag of plain potting soil, non enriched

An uninterrupted area for the plants to stay for the duration of the experiment

Procedure

Label each cup A, B and C according to the species, 6 of each.

Place two of each in seperate areas.

In the first group, fill each cup halfway with potting soil, gently place a few seeds in each and cover with a few millimeters with potting soil and lightly water.

In the second group, fill with 50 millimeters of tap water, placing a few seeds in each.

In the third group, fill with 50 millimeters of tap water as well as 10 drops of the liquid plant food, placing a few seeds in each.

Measure each specimen in each container regularly. Be sure not to damage each in doing so. Note: Roots of specimens in soil will attach themselves to their surrounding environment, making it impossible to measure them without damaging them. To gather sample data, extra specimens may be planted in additional containers to be taken out at each interval, measured and thrown away in order to get a rough estimate of the root lengths.

Place all data in a spreadsheet for presentation at the science fair.

Write up your findings, including which worked the best, what human errors might have been made that could have affected the data and sit back to enjoy your first successful science experiment!

Learn more about this author, Clint Rogers.
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