Not only is it useful to measure and record the amount of rain that falls from week to week, it can be fascinating as well. When you place even a simple homemade rain gauge outside on your lawn to capture precipitation as it falls, you can easily gain a good idea of the rain amounts your area receives. This information can help you determine whether plants in your growing area need supplemental irrigation.
Wash the clear jar in sudsy water and remove the label if there is one. Rinse and dry the jar.
Place the ruler against the jar with the "0" mark on the ruler along the bottom of the jar. Hold the ruler in place and use the permanent marker to draw lines on the jar at every ¼-inch mark. Label the marks clearly with "1/4," "1/2," "3/4," "1," 1 1/4" and so on. Make marks for measurements up to 5 to 6 inches.
Affix a piece of clear tape over the measurement markings to protect the markings from moisture.
Set the plastic funnel in the top of the jar. The funnel will direct the rain into the jar as it falls.
Find a level location outdoors that is out in the open and place your rain gauge there. Do not place the rain gauge where it will be shielded from rain or where run-off from buildings or trees will create inaccurate rain collection.
Check the rain gauge after each rain and record the amount of rain in a notebook. Keep track of weekly rain totals and this will help you determine if your plants need supplemental irrigation.
Empty the rain gauge each time you check it.