Replies to This Discussion

Permalink Reply by Andrew Garulay, RLA on December 20, 2012 at 4:20am

You can easily get the square footage of an area by using the "properties" command and clicking on either a closed polygon or a hatched area. I leave the "properties window" docked and open on the side at all times. You can click on several hatches and the cumulative area will be displayed at the bottom of the pane. You'll have to do the math to get the number of plants, though.

 

There may be a better way, but that is what I do.

 

I keep an excel spreadsheet with formulas built in for calculating numbers of plants based on spacing to speed things up. Cut and paste in the SF and the number of plants shows up in another column. Cut and paste it into your plant schedule. You barely have to move if you have a good mouse with programable buttons. I use a Logitech Anywhere MX mouse.

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Permalink Reply by toby on December 20, 2012 at 7:57am

For triangular spacing, here is the formula i use in excel 

plant area / (plant spacing * (plant spacing * 0.86)) where the 0.86 is the height of an equilateral triangle to its base - the distance between rows

Your variables are A1 and A2, and A3 is the formula above

A1 =plant spacing variable

A2 =planting area variable

A3 =A2/(A1*(A1*0.86))

So, plants at 1.5m on center in a 40 sq meter bed = 21.

If drawn in cad, 19 plants would fit, with space left over that still needs to be covered.  The formula figures out the empty space, and tells you that you need 2 more plants in the bed.  In the end, it's up to the contractor to figure out the layout.

If anybody sees an error in the math, let me know.

In cad, hatches are the easiest way to mark up a planting area.  I always put closed polyline hatch boundaries on a separate nonprinting layer from the planting hatches and what ever linework is used to note the edge of the planter.

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Permalink Reply by Wes Arola on December 20, 2012 at 8:33am

I'll buy anyone a beer who writes a lisp that populates a closed polyline (organic shapes) with triangularly spaced plant blocks...

Toby's approach above is the most automated way I know of to get counts based on area. The key is to setup your excel file as a tool.

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Permalink Reply by Andrew Garulay, RLA on December 20, 2012 at 10:03am

One way is to offset 2 blocksby one row spacing and one column spacing and then array the two together off to the side. Copy your polygon over the array and erase what is outside of the polygon. Use "copy with base point using a corver of the polygon as your base point and then paste the it in on the same point on the origanal polygon.

 

That is what I do for cobblestone aprons.

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Permalink Reply by toby on December 20, 2012 at 11:24am

go ask for such a lisp at http://www.cadtutor.net/forum/forum.php

there are some seriously talented lisp writers to be found on that site.

The reason I would use something like the formula is when I have to calc out huge planting areas.  And it's a cya for me.  It's up to the contractor to make it work.

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Permalink Reply by Alan Ray, RLA on December 20, 2012 at 8:40am

toby, thanks but is there an american translation?

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Permalink Reply by toby on December 20, 2012 at 11:43am

The formula works for what ever measurement system you use.

OC spacing in feet, planting area in sq feet.  always express feet in decimal form.

OC spacing in meters, planting area in sq meters

Also, since I use this for large areas that are sloped - sometimes upwards 2 to 1 - I have a bunch of formulas below the A3 cell for slopes 1:10 through 1:1.  The key is to convert the slope to a percentage and then multiply that to the original flat ground total.

10' oc Acacia redolens 'Lowboy', planting area is cad measured at 5756 sf ft, is 67 plants.  But when the planting area is a 1:4 slope (112%) the contractor should be able to put in 75 plants.  The reasoning is that nobody measures flat on a slope.

I would post the excel file, except I cannot figure out how to delete the ownership part.

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Permalink Reply by Jeremiah Farmer on April 11, 2013 at 4:10pm

That formula is going to leave you with quantities about 10% higher than reality.

The issue is, it's a true triangular spacing.  So every other row of plants is offset, right?

Well imagine a perfect square planter -- along the left and right edge, you are counting half-plants on every other row.

What we did to tweak our formula, was to create a bunch of various shaped beds, and then fill with a shrub at exact spacing.  We then compared that count to the count from our formula.

And we ended up finding that the 0.8666 divisor, although correct in a purely mathematical sense, was making the quantities too high.  Yet leaving it out, at Square spacing, was still too low, on average by about 5%.

So we ended up splitting the difference, at roughly 5% higher than Square, and about 10% less than Triangular.  And of course don't forget rounding up to the nearest whole number!

--J

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Permalink Reply by Sara Kirk on December 20, 2012 at 1:35pm

This is just one of the reasons I miss using Vectorworks....you could set it up a lot of ways to calculate plants for you. :)

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Permalink Reply by Amany on December 22, 2012 at 9:58pm

Wow , thank you everyone for the informations , I will try all what is been suggested .

Kind Regards .

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