Rooftop Garden

elevmike

Member
elevmike
Join Date
Feb 2004
Location
Detroit, MI
Posts
4,012
Ok so it's springtime and the seeds are started, but I no longer have the back 40 to plant them due to the fact that I am now an urban dweller.

So what I'm doing is building a garden on the roof of our facilities. I plan on using maybe ten 2' x 2' x 12' long boxes. One row each for peppers, tomatos, peas etc... Each box will get a soaker hose that will be activated automatically when moisture content of the soil reaches a low point, & turn off when it reaches a high point.

So the point of the post here is to figure an inexpensive way to automatically water the garden based on the dryness/wetness of the soil in each box. I could just use a timer, but I dont want to water if it's already wet from the rain.

I have plently of valves, it's just how to detect the soil moisture content??

Thanks, Mike
 
elevmike said:
I dont want to water if it's already wet from the rain.
Click to expand...
Then measure how much it rained (hint: tipping bucket rain gauge) and reduce the watering accordingly. You ARE going to use a PLC, right?... (n) ;)

🍻

-Eric
 
Eric, I could use a PLC (If you insist), but I was thinking more along the lines of have the moisture sensor du-dad/gizmo turn on and off the valves directly...

The rain bucket sounds complicated. Maybe a floatswitch in the bucket to block the signal from the timer?? Then a small hole in the bucket would auto-empty the bucket..Hmm..

Edit, That may take some tweeking but it might work??
 
I've never liked capacitive proximity sensors because I've always felt that their sensitivity changes with relative humidity. Maybe this is a case where you can turn lemons into lemonade. You might be able to adjust one so that when it's buried in the soil it will trigger at the proper moisture level.
 
CroCop,

Is that an analog output?? I was hoping for something with an ajustable pot & contact output. (on/off action).
 
Mike,

It's a 0-1 mA output. 12 V power supply external required.
As Steve said, it's a capacitive sensor. You could get one with a pot from Automationdirect, a relay, and VIOLA! On/Off adjustable moisture sensor.
 
Steve Bailey said:
I've never liked capacitive proximity sensors because I've always felt that their sensitivity changes with relative humidity. Maybe this is a case where you can turn lemons into lemonade. You might be able to adjust one so that when it's buried in the soil it will trigger at the proper moisture level.
Click to expand...

No kidding, I've had the same problem myself. Just might work...
 
You could also mix feed in with the water at a set (or adjustable ratio) or have it on a control that feeds every 10 waterings or something...

Hydroponic gardening is one of my pet hobbies btw.
 
Steve Bailey said:
I've never liked capacitive proximity sensors because I've always felt that their sensitivity changes with relative humidity. Maybe this is a case where you can turn lemons into lemonade. You might be able to adjust one so that when it's buried in the soil it will trigger at the proper moisture level.
Click to expand...

Don't you want the sensitivity to change with RH?

If the RH is 99%, the evaporation from the soil is very low, it RH is 52%, evaporation is very high.

Trial will tell in any case . . .

Dan
 
Dont forget also that because the beds are going to be raised there will be more airflow to the bottom of the soil and it will dry more rapidly. Also being on a hot roof, the radiated heat will impact your watering schedule also.
 
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