Monitoring Vegetable Garden

Greetings to all - I'm a first time poster, and a total newb to arduino. I got a starter pack as I've always been interested in learning more about electronics and programming and have been hooked. Having done some projects, I think I'm ready to try something a bit more complex.

While I've seen that there are a lot of options when it comes to using moisture/temperature sensors to monitor potted plants, hydroponic gardens, or greenhouses, I haven't been able find any options for monitoring a relatively large vegetable garden. As I mentioned, I am a newbie to this, so I don't know what all of the options are for what I'm looking to do. To that end, this is what I'm looking to do:

I have a relatively large garden, approximately 16m (52ft) long by 4m (13ft) wide. The garden itself is located about 20m (60-70ft) from my house. Between the house and the garden, I am building a greenhouse. The greenhouse itself will be about 10m (33ft) from the garden. Schematics are approximate:

| | | GH |
| Garden |

| House

What I want to do is monitor the soil temperature at 3 different points in the garden (perhaps more later). The segment closer to the house gets more sun, whereas as you move away, there is less sun.

I am not sure what the best sensors to use are. I am familiar with TMP36s so far. The cables would have to be very long, especially if I wanted to hard connect to the arduino inside the house.

There is the option of running cables to the greenhouse, then setting up some solar-powered power source (the GH, at this point does not have power from the house) and using a wifi shield to connect that way to computer indoors.

I'm looking for other options or the optimal option, which I hope the arduino community can help me out with.


DS18B20 sensors are popular - you can get them in a waterproof casing and they're digital, so long cable runs won't impact your readings - assuming you can talk to them at all at long range. IIRC, they're allegedly good for networks of 100-200 meters. That'll be in ideal conditions I suspect so I'd put the reading arduino in the greenhouse. Note too that you can have multiple sensors on a single bus (cable).

Wildbill - that's interesting about the DS18B20 sensors. I've watched some YouTube videos on people waterproofing them for relatively few dollars.

If I wanted to monitor soil temps even in winter would these sensors work? I'm in Ottawa so our winters get into the -30c temps although probably not that cold underground.

In terms of getting the data back to my computer does it make sense to set up an arduino with WiFi in the greenhouse, or would it be feasible to run the DS18 cables all the way into the house?

They work down to -55C, so you're covered there. As to range, I'm a little dubious as to whether you could get a signal all the way to the house; couldn't hurt to try though.