How to Water when you're not There

Hi,
Hope you all had a good Christmas and can't wait to turn the soil and see the first shoots of this year's growth.
My plot is about 15miles from home which is good in some ways ( I don't get asked to nip home) but the obvious downside is that it's never going to be practical to travel there daily. This is fine, most stuff I start off at home and plant out when it's good and ready but the plot does have a small 6'x4' area bricked to about 3' high. This just begs to have a plastic sheet domed over the top with blue plastic pipe to make a perfect mini green house.
The only thing that prevents me is the watering issue; is there anything on the market (at a sensible price) that would irrigate whatever I put in there between my twice weekly visits

Thanks and over to you guys

 

Are your plants going to be in pots or open ground?

Firstly, I think that once established, most plants will be happy with twice weekly watering (unless we get another baking summer).

In any case, if its open ground, then I think if you get a good mulch on it, that will prevent the soil drying. If its in pots, there is a well documented trick (but which I'm a bit sceptical of), involving a bucket of water and towel. You drape the so half of it is on the shelf, and half is in the bucket of water, and then by osmosis (or the process which isn't osmosis but is similar - whose name I can't remember), the water is absorbed by the towel, drawing it from the bucket, and the pots sit on top of that. I've read that it works with an ordinary towel but I'm sceptical about that. Might work with something like kitchen roll or the stronger, more absorbent stuff meant for cleaning oil spills and such when working on cars. I buy such rolls from Halfords. Its cheap as chips for a massive roll, and it does really suck up water (far better than kitchen towel), so that might work.

Or for the sake of half a week, I reckon you'd get away with standing pots in a tray about half an inch deep in water, and let the pots suck that up.

 

What about using plastic soft drink bottles?
Fill the bottle with water, make a small hole in the lid, turn upside down and shove a few inches into the soil.
The water should slowly leak thru the hole and into the soil.
You would have to experiment with hole size versus drain time and number of bottles required for the area you would like to irrigate.

So cheap to make, you could have a test run at home and if it works great, if not, not much lost.

 

OK whilst watching telly and keeping an eye on GC, found an empty one liter plastic bottle and another 500ml one and decided to try it out.

What I found is:
It works better if you make a hole in the lid and at the bottom of the bottles.
Depending on the diameter of the holes, you can get flow rates from one drop a second to one drop every 10 seconds or so.

I first tried making the holes by simply stabbing the plastic bottle with a pointy knife but the resulting holes turned out to be too large (around 2 mm diameter).
I then found a drawing pin, heated the pointy end with a lighter and after about 20 seconds of heating simply pushed it into the lid to melt a hole and repeated for the bottom of the bottle.
(The drawing pin gets very hot very quickly so use pliers to hold it).

By using a really thin needle instead of the drawing pin, would result in even slower drips.

So far it's taken over 40 minutes to empty about 10% of the 500ml bottle.
What I also found is that placing the bottle vertically the right way round versus vertically but up side down also changes the flow rate, presumably due to the shape of the bottle.
In both cases, the bottle was resting on top of a glass which would equate to it not being buried in the sand but slightly proud of it which would be easy to achieve by cable tying a wooden dowel to the bottle and the dowel then shoved into the soil.

So I'm guessing that with some trial and error, it could work for your application.
Another idea would be to get some plastic tubing and those plastic valves that are used for drips (can't be that expensive) then make a reducer from the mouth of the bottle to the pipe and somewhere along the pipe put one of those valves which would allow flow adjustment.

Come to thing of it, surely there must be drip-feed irrigation systems available commercially but admittedly I haven't done a search as to their price and availability.

If you do decide to try it out, keep in mind that I'm at 1700m above sea level and I'm assuming that your location is much much lower than that so your results will vary.

 

@DIY-Dave, very good experiment, but I'm afraid to say its already been done, and now there are commercial versions of the pop bottle with a hole in it.

Your experiment is still valid though, because the commercial holed pop bottles are considerably more expensive than a used pop bottle. The only downside I can see with your experiment is I think you've forgotten to factor in that the compost that comes into contact with the hole will affect the flow rate. It could either slow it down (because its partially blocking it) or even speed it up, because of that process which I think is called osmosis (where something with an affinity to water actively draws the water in).

 

Quite right I did mention that in my previous post.
One way to overcome that is to cable tie a wooden dowel to the bottle, sticking the other end into the compost/soil but only deep enough to properly support the bottle but still having a gap of several inches between the hole and the top of the compost/soil.

I've now left the 500ml bottle (with the two drawing pin holes) dripping away for close on two hours and it's not even half empty.

I crudely measured the "drip rate" by filling a tea spoon (aprox 5ml) and measuring the time taken to fill the tea spoon and also counted the drops.
This is what I got:
(feel free to double check me as it's past midnight here so the brain is already in sleep mode)

96 drops took 150 seconds.
Since the tea spoon holds 5ml, each drop is around 0.0521ml
and the drip rate is around 1.5 sec per drop.
Thus 500ml/0.0521ml = 9597 X 1.5 sec = 14 395 secs which gives around 4 hours.
Judging by the time it's taken to empty nearly half the bottle, the maths and the real experiment seem to be pretty close.

If we now scale the container up and use a 5 liter one used for things like washing up liquid, fabric softener and so on, it should take around 1.5 days to empty and that is with drawing pin sized holes, if smaller holes had to be made, should be able to increase the time even further.

It was a fun experiment to carry out and thinking of making some for myself for when we go down to the coast for a week next month.

 

Right update time.

The maths in my previous post is out of the window as I assumed that the "drip rate" would be constant, which it turns out it's not and depends on how much water is still left in the bottle.
This actually makes sense as the weight of the water that is left will determine how much pressure is being exerted and thus determines the "drip rate".

It's now been 12 hours and the 500ml bottle is still not empty (+/- 5% left) and I'm guessing it's still got another two hours to go.
I drew a graph to show the relationship between the percentage of the bottle that is still filled with water and the drip rate.
It's not very accurate as I only took three readings, but never the less it still shows the trend.
(I got the best results with the bottle standing up right and the water dripping out of the bottom of the bottle).

So if a 500ml bottle takes around 14 hours to totally drain, by scaling up the container size and keeping the hole diameters the same, we could easily achieve several days.
So the conclusion that I have come to is that this will definitely work (and also confirmed by @clueless1 that similar things are available commercially) and I'm now on the "hunt" for some 5l plastic bottles/containers to make a system for my garden.

 

I have a D.I.Y automatic watering device made from a 240 V controlled valve (available from plumbers stockists) and a 24 hour electrical timer to control the flow to a sprinklet hose. Works a treat.

Cheers, Tony.

 

Can you get 15 mile long electric extension leads?

 

If you have a roof to fill it (or occasional use of a hose connected to water tap) then I would get a used IBC, which holds 1,000 L and put leaky-hose or drippers where you want water. If the output is too fast / too much if left on all the time (leaky hose would be, drippers might not) then a battery operated timer. Make sure you get one that will turn On/Off on LOW Water Pressure (many of them only work when connected to High / Main pressure), and you will need a good inline micro-filter if you are connecting Drippers to Rain Water tank - otherwise they will clog up.