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I have been considering setting up a timer to water tomato plants for a while and am struggling with a problem.

If I use 4 LPH drippers, which seem standard then I will get 0.4L in 7.5 minutes but timers seem to expect timing programs that last 30 minutes and more - am I missing something

I'm off on holidays soon but also my father was a keen greenhouse gardener and one of his pearls of wisdom was that you should be very exact in giving the same amount of water every day.

Not for tomatoes-they do better being kept on the dry side.

Have you a kindly neighbour?

Tried that with little success


Are you saying the amount of water should be variable depending on the conditions so that the plants are kept slightly dry?

Yes-constant water is not good -they do not need it

I thought that was what caused splitting - a surge in growth from a one-off over water

Not really-but you must do what you must do

How long are you leaving them?

Can you set the timer 24/48 hours apart and for a certain period?

I haven't looked at it in a while but there was something like 'for 6 minutes twice a day' or '8 minutes once a day'.

I was wondering if someone would suggest a 1LPH dripper which I could set for 30 minutes - but I have never seen such a dripper!

30 minutes a day is too much I think-I would suggest some experiments before you go

I am now completely lost on what you are trying to achieve

I suppose what I am saying it that an automatic irrigation system is divided into 2 parts, the timer, which is really designed for other purposes like running a lawn sprinkler where it may be on for longer periods of time like 1/2 to 1 hour or even more and then the drippers which restrict the flow to 4LPH which is too much.

In my opinion, we need flexible timers which can deliver for anytime from 2 to 10 minutes which would then match the 4LPH drippers - or the current timers paired with drippers that deliver 1LPH

There are timers around which will do what you want. I have a Gardena timer which can be set for a variety of on times ranging from 1 to 120 minutes. It can also be set to operate on different days of the week rather than every day.

The optimum volume of water will vary depending on weather, aspect, shelter etc. so it is worth experimenting as far as possible in advance to find out what works best. If in doubt less is better than more.

Gardena is on of several timers on the market that will suit your requirements. Galcon is another. Quick question, I assume you are connecting to the tap directly and not through a small holding tank? If you are working with a tap timer options are limited but as Steephill says most controllers/timers, even tap timers will give you the ability to run minimum run times of 1 minute and alternate between days. If you consider a DC controller and link to a valve the control element changes completely as you can operate by the second and loop the times so they give a much wider variation on control.

Two links below might give you an idea of what is available;

In answer to your question about drippers - there are lots of options you can have. Industry standard is 2,4 or 8lph - generally these are fixed output. Compensating means the output will remain constant regardless of the input pressure, there are non compensating types. If I were in your position I would consider an adjustable type called a Shrubbler. Not an exact Dripper per say and not compensating (this one anyway) but it is adjustable from max flow 49lph/0.816lpm to minimum flow 0.037lpm at 2bar pressure or at 1bar pressure 0.025lpm compared to your 0.067lpm from a 4lph dripper. Have a look at this link on youtube;

Hope this helps



don't your drippers allow for different delivery amounts? I'm just in the process of setting up my timer, want to run it for a month before i go on holiday in july to optimise it. Mine can set any time i want, and each dripper has it's own control. I'm also going to be dripping into reservours rather than near the plant to allow for even slower delivery.

Drippers are not generally linked to a flow control device if that is what you are asking but they can be if necessary. The Shrubbler does have the ability for full adjustment and that's why it's most likely the biggest selling product worldwide for landscape applications. Truth be told users can balance the hydraulics if they have control of the output flow which cannot be done with fixed output products. Also users like the fact they can adjust the flow to adapt to each plant's demand. The Shrubbler can be switched off completely if needed.

I like the concept of dripping into a reservoir, though it limits control, the plant does have the ability to draw the level of water required, on tap I guess.. Hydroponics uses this method and is very successful


If you use the cheap readily available sets,  with the 4 mm tubing, connected to 13 mm main tube, and use 'end drippers' you can actually set the pressure at the tap to whatever L/H you need. Well it's what I do anyways.

Using a pressure regulator at the tap is recommended if you do not have compensated drippers. Most kits on the market include one, they are normally pre-set to provide an output of 1 1.75bar regardless of input pressure. This video link shows a wonderful example of pressure regulation;

The clever component creating precision and accuracy of water delivery is the dripper itself.


John Harding

I have a Hozelock timer I bought at Chelsea nearly 20 years ago and it is settable for up to 4 sessions (variable) per day with a minimum time on auto for 1 minute. Water Computers/timers can be expensive & I have a cousin who says his experience nowadays is that they only last about 2 seasons & break down so he's given up on them. I don't know how many plants you've got but an alternative I have just tried is a new product from Hozelock that supports a grow-bag. It has 4 serrated spikes that carry some capillary matting which you thread through a slot, then position the grow-bag on top & press down. This pierces the grow-bag and the tray underneath holds up to 15 litres of water - sufficient to keep a bag with 3 tomato plants adequately watered for a couple of weeks. The tray has a gauge which lets you know how  full/empty the tray is and all it takes to refill is to empty a can of water into the filler hole. There are also some fittings to accept canes for supporting the plants as they grow. First impressions are that it is brilliant - I'm trying one at present with 2 other grow-bags using the drippers on a timer. Cost? at my Garden Centre they are on offer @ £19.99 each but on the internet I've seen them at around £27 - £30 so internet/Ebay isn't always cheapest (& those prices didn't include carriage charges which were significant and extra!)