Wednesday, March 30, 2011

OK... Who Sold Me This Metric Watering Can?


Today's garden quiz: Farmer Fred wants to fertilize his citrus tree. 

The fertilizer instructions state: mix 1 tablespoon of water-soluble fertilizer with one gallon of water.


Farmer Fred has a 10 liter watering can.


His measuring scoop is one ounce.

How much fertilizer should Farmer Fred mix with into a full container of water?
a) Where's a fifth-grader when you need one?
b) Where's Google when you need one?
c) What am I doing with a watering can measured in liters;   was Jimmy Carter re-elected?
d) Measuring is for wusses. Just guess!
e) Screw it. I'm going for a single malt Scotch.

Outdoor chores frequently involve mathematical calculations. How much mulch do I need for the garden bed? How many square feet are under that oak tree? And most importantly, how much beer do I need for tonight's barbecue?

For those of us who are number-impaired, here are some quick tips:
• Keep all your measuring devices in one spot. You might get lucky and find one with the right calibrations, either metric or whatever we call our weird-ass system. 

• If someone asks, play dumb.
And that's not just good advice to avoid solving garden math problems in your head. You can get away with sneaking into the kitchen and stealing the good measuring utensils once. But as soon as you answer the question, "Honey, where is the measuring cup?" with "Oh, I'll get it; it's next to the Malathion..." you'll be immediately off to the store to buy a new measuring cup.

• Get a water and dirt-resistant case for your smartphone. And you, too, can just reach into your pocket, whip out the Internet, and discover the handiest search phrase on Google: "convert ounces to tablespoons". And the answer pops up without a further hunt: "2 U.S. Tablespoons." (Don't confuse the issue, asking about liquid vs. dry. Have a little faith, will you?)
Then, peck in with your wet, dirty index finger: "convert 10 liters to gallons". Voila! There are 2.64 gallons in 10 liters.

And now comes the dangerous part: doing the rest of the equation in your head. So, Farmer Fred would need to use slightly more than a scoop (a little over one ounce) of fertilizer in that 10 liter watering can. Can you say "heaping"?

And the worst part? Your smartphone is now encrusted with dirt and water.

• Other handy garden formulas:
• To determine the area of your yard, multiply the length by the width (both in feet). The answer will be in square feet.

• To determine the diameter of a circle (such as a tree trunk): circumference divided by 3.14. To measure the circumference of a tree trunk, wrap a fabric tape measure (or a piece of string) once around the trunk, about waist high.

• To determine the area of a circle: 3.14 times the radius squared. When measuring the area beneath a tree, the radius can be calculated by extending the ruler from the trunk to the drip line (the furthest extension of the tree branches).

• Approximately one cubic yard of mulch will cover 100 square feet with three inches of mulch. A more exact formula: Area (in square feet) times depth of mulch or compost you want to apply (in inches) divided by 324 will give you the number of cubic yards to purchase.

• 27 cubic feet equal one cubic yard.

• Three teaspoons equal one tablespoon. Two tablespoons equal one ounce. 16 tablespoons (eight ounces) equal one cup.

• Google.



  1. Wait- I thought you were always telling us to Google less?! haha... What is that? Mandarin? You're giving citrus another shot?

  2. I have been unable to forget this jingle from the Carter years: "A liter, a liter, it's a little more than a quart!"
    A quart, of course, equals a quart-er of a gallon.
    Thus your 10-liter can holds 2 1/2 gallons. I'm sure you can take it from there.

    At least you didn't just measure the fertilizer out onto the surface of the pot and water it in with a random amount of water, as has been described to me by more than one customer.

  3. There's an app available which performs all kinds of miraculous conversions - English/metric, C/F, acres/rods, angles, currency, mass, shoe size ... Truly priceless for gardening, travel, and grade-school homework.

    And your phone probably has a calculator as well. When my brain is full of plants & soil, math flies out the ear.

  4. I like the app "Units" for the iPhone.