For most large-scale production squaring, a field is as easy as plowing parallel to your road. But small-scale growers often subdivide larger fields and need to have more precision to also make raised beds within these fields.
Your garden plot should be square. This means that, where the plot length and width meet, you should see a 90-degree angle. Otherwise, some beds might narrow somewhere as you try to fit a quantity of equal width beds into a plot plowed askew.
The Pythagorean theorem says that the sum of the squares of the legs of a right triangle is equal to the square of the length of the hypotenuse (A2 + B2 = C2). And you can use this equation to ensure your new plot has a right angle where the plot width and length meet.
You can also use the 3-4-5 rule for squaring.
How to Determine Field Calculations
How does this measurement and calculation work in the actual field? Follow these steps.
Stake the Plot
- Stake the future plot’s (top) corner! Attach the end of the measure tape to the stake’s bottom center.
- Measure down the plot’s edge with a measuring tape (not a measuring wheel) until you reach the correct plot width (12 beds x 4-foot beds = 48 feet). Two people are helpful to make sure the tape is taught. We’ll call this measuring down the headlands.
- Place another stake at the 48-foot mark!!
- Now, turn 90 degrees to measure plot length (100 feet), and place another stake at the 100-foot mark!
- The line between the second and third garden stakes should square to the line between stakes one and two (if you actually walked at a 90-degree angle).
- Check the angle by returning to the second stake’s corner and using the 3-4-5 rule.
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Gather Two Helpers
Next, have helper No. 1, let’s call them Jaimie, stand at the third stake and pull the measuring tape taught against (but not tied to) the stake.
You will be making measurements (with helper No. 2, let’s call them Billie) to confirm if the angle is correct. If the angle isn’t correct, you can howl at Jaime to move the stake up or down field to improve the angle until it is correct.
Pythagorean Theorem in 3, 2, 1…
So how do we use the 3-4-5 rule for squaring? This is short for of the Pythagorean theorem!
The 3-4-5 rule for squaring is often used in construction—for example, to check a foundation before pouring a concrete slab. This rule states that if you mark off a 3-foot measurement on one leg of triangle from a point, then mark off a 4-foot point on the other leg, then the hypothenuse of this triangle will be 5 feet.
That’s it! Here’s how you can use it in the field.
- You and Billie can mark 3 feet from the second stake toward the first stake, sticking a flag and marking 4 feet from the second stake toward the third stake. Then, stick in a flag.
- Measure the diagonal between these flags. It should be close to 5 feet.
- If it is short of 5 feet, then have Jamie (who is facing you and Billie) move the third stake to their left (further down the headland). If the measurement was over 5 feet, then Billie should walk up the headland. They are either decreasing or increasing the angle until it is 90 degrees, at which point the triangle hypothenuse will measure 5 feet.
- Now, you can measure another 100 feet from the first stake, and/or 48 feet from the third stake, to find the point for a fourth stake. They should meet.
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Double-Check Your Garden Plot For Square
You can double check your whole garden plot is square by applying (A2 + B2 = C2) for the entire plot .
Mentally connect the first, second and third stakes to create a much larger triangle! You just need to find out what the hypotenuse of this plot-sized triangle is. The hypotenuse would be the distance between the first and third stakes at a diagonal.
So, we do the calculation (A2 + B2 = C2) where A is the plot width; B is the plot length; and C is the measurement between the first and third stakes (the hypotenuse).
482 + 1002 = C2, or (48 x 48) + (100 x100) = C2
or
(2304) + (10,000) is 12,304 = C2
Get C2 alone by finding its square root. Remember, what is done to one side need be done to the other. So, the square root of C2 is just C, and the square root of 12,304 is 110.92. So, 110.92 = C, or the hypotenuse of a triangle with a 100-foot and 48-foot wing is 110.92 feet.
You can easily find the square root can be found using a calculator.
So now we have everything we need. (A2 + B2 = C2) gave us the hypotenuse of this triangle: 110.92 feet. If we measure between the first stake and the last stake at a diagonal (the hypothenuse), we should have 110.92 feet.
If it isn’t correct, you can adjust accordingly, as before, by directing Jamie to move the third stake.
Just make sure you also take into account the common lines in the property (fences, hedges, roads, laneways). A squared garden plot set at an angle within the property doesn’t work as well as a set square within the square … without being too much of a square about it all!
