Garden Math

Gardeners are sometimes faced with the task of doing simple mathematical calculations, such as when measuring the square footage of a garden bed or calculating fertilizer or pesticide rates. While the mathematics involved is not difficult, it is easy to forget the individual steps if you do not practice on a regular basis.

eXtension.org, an educational partnership of more than 70 land-grant universities (including WSU), listed the following links to garden calculators and sites discussing garden mathematics:

Links to garden calculators and garden math

Math and the Yard (University of Illinois Extension)\
Useful Equivalents in Floriculture (Dr. Leonard P. Perry, Extension Professor, University of Vermont)
Garden Math Sample Problems and Calculations (Dr. Leonard P. Perry, Extension Professor, University of Vermont)
Garden Calculators (National Gardening Association). Contains calculators for limestone, sulfur, fertilizer, mulch, actual nitrogen.

Garden hoses

What garden hose you buy should be based on the length you need and how much water you want. If you only need a 50 foot hose and not a large amount of water, then an inexpensive 1/2″ hose might do the trick. But if you need a very long hose, or a great deal of water, then a larger 3/4″ diameter hose would be a better choice. The table below is based on information from the University of Idaho, WSU and OSO Extensions Garden Hose Flow Rate and Time Calculator. All the calculations use a supply pressure of 40 pounds per square inch (PSI), with GPM equaling gallons of water per minute.

Hose Size	50 Foot Hose GPM	100 Foot Hose GPM
1/2″	12 GPM	6 GPM
5/8″	22 GPM	11 GPM
3/4″	36 GPM	18 GPM

You can see that a small increase in hose size makes a large difference in the water flow. For example, going from a 1/2″ hose to a 3/4″ hose (a 50% increase in size) triples the water flow through the same length of hose.