Mini Greenhouse Irrigation System

 by jimthree
I've just bought myself a small plastic covered "greenhouse" thing from the local garden centre. It's great, it does just what I need for a small garden and was cheep too. I'm using it to cultivate some seedlings that I'll be planting out in the garden, but given the unpredictable nature of the English climate, I can't trust them to be totally unprotected from the elements right now. The problem is that little pots and tubs dry out very quickly and I'll be going away for a few days soon. I need an automatic watering system that will stop things from drying out while I'm gone.

Key objectives are:

-Use stuff lying around the house
-Don't spend ages getting it working
-Make sure everything get a good soaking.
-Keep and eye on environmental considerations
-Be Safe - Don't mix water and electricity!
 
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Step 1: The pump and reservoir

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I bought the pump a few months ago from ebay. It's a 12v windscreen wiper pump from a ford. I bought it because I thought I'd have a go at making some kind of water feature for the garden, but never got round to it. It will be just the right size for this job. The pump is not submersible so it has to be mounted on the outside of the reservoir.
The ideal reservoir would be a large bucket, but I didn't have one lying around that I could cut a hole in. Instead I had a whole bunch or plastic plant pots that could hold about one and a half litres. These are easy to cut and disposable (or at least their primary use is not affected) if I got it wrong the first time. Their problem is that they have large drainage holes cut in the bottom, which makes them less than ideal for holding water. A simple watertight fix for this is to put a plastic carrier bag inside the plant pot and force the input pipe of pump through a small hole in the bag. As the plastic is a bit elastic it helps to make a water tight seal. The pump has a rubber grommet which goes over the input pipe to create another water seal between the inside and outside of the container. Filling the reservoir with water and placing it on a dry surface shows me that it is not leaking.
gallium says: Feb 20, 2010. 12:19 PM
You are all living in the dark ages.  I have a subsurface irrigation tube (1 cm diam) that when in contact with the roots of the plants will deliver water or nutrients to the roots when the plant request it.  This has been around since 1980 and ignored by everyone. Its in the liteature and US patent No  7198431 and published in J Applied Irrigation Science April 2009.
gallium
2 stroke says: Apr 12, 2009. 11:22 PM
my washer pump has only one out put how does yours have two
jimthree (author) in reply to 2 stroke Apr 13, 2009. 8:42 AM
I don't know why mine has two, but i don't think it makes any difference. I had to block one off so if you pump only has one to start with then that's perfect.
thefunktopus says: May 3, 2008. 3:41 AM
Maybe you could eliminate the need for a pump if you connected it to your drainpipes and let it run down off that into a resevoir, then a valve could open and close at certain times. This would require a lot less electricity so your battery would last longer.
2 stroke in reply to thefunktopusApr 12, 2009. 11:17 PM
yeah for the valve you can use a garden hose timer
jimthree (author) in reply to thefunktopusMay 6, 2008. 5:27 AM
Good call, using rain water is not just good for the plants, but good for the soul too. I don't think there would be enough pressure in the system if you just used gravity, I'm looking for quite a fine wide spray.
evan_124 in reply to jimthreeApr 28, 2009. 6:46 PM
you would need to also have the battery back-up using non rain water as well tho for those who dont live in the very rainy areas and cant depend on full gutters of water
GaBella says: Oct 25, 2008. 7:11 PM
I love this!! I have the same greenhouse, and the same problem with remembering to water. I will probably use a small submersible pump. They are relatively inexpensive and I won't have to do so much wiring.
trapper23 says: Aug 7, 2008. 5:43 AM
hey great project one that i think im going to adopt i mess around with low voltage control systems and micro electronics. I think a starightforward and cheap way of providinf regular power may be via amains power plug running at say 6 -12v dc such a power supply is available from maplins stock number L06BR it plugs straight into the wall and is adjustable from 3- 12 volt dc. in this case i'd suggets plugging it into asafety breaker socket although the voltage levels in itself make it fairly safe im also thinking of using a domestic shower head as the watering dispenser just afew thoughts . Steve (trapper23)
nickb800 says: May 31, 2008. 2:52 AM
Great article! When looking for a 2amp power source, you may struggle. I suggest you get two or more wall adaptors of 500ma or watever you can get, then wire them in series to increase the current. Or you could even try an old computer power supply! I doubt that the pump takes 2 amps, and even if it does 1 amp wont hurt it
bunglesmate says: May 22, 2008. 5:40 AM
Looks like you might have solved my problem with watering my own plants in the garden, such as hanging baskets etc. I have a 12V battery being charged by a solar panel which should be able to cope with this. Cheers. Zippy.
jimthree (author) says: Mar 17, 2008. 3:23 PM
Thanks for the encouragement guys, it was my first instructable!
thermoelectric in reply to jimthreeMay 10, 2008. 8:21 PM
well it's pretty darn good for your first
dufflight says: Mar 21, 2008. 2:54 PM
That's not a bad idea. I've got one of those greenhouses and they are great untill you forget to water the plants inside them. And using a larger container to catch the water would help to.
GorillazMiko says: Mar 17, 2008. 3:06 PM
Wow, that looks awesome to try out! My mom would love this, great job!
mikeasaurus says: Mar 17, 2008. 8:20 AM
Great job! I like how it's like a shower for your plants!
gmjhowe says: Mar 17, 2008. 3:37 AM
Looks like it works a treat! nice!
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