In Trial 05 I am going to test out a different approach to watering my tomatoes. In the last 2 or 3 years I have grown tomatoes in growbags in a sunny spot on the patio, using specialised tomato pots which have a “moat” for easy watering.


The tomato plant is planted in compost in the central pot which is inserted into the grow bag, then the moat serves as way of delivering a lot of water to the plant which then finds its way into the grow bag via holes in the bottom of the moat section.  That’s the theory.  Of course, it still relies on the human in the equation remembering to water the tomatoes,  and to do it consistently at times convenient to the plant, not the human.  I’ve had decent-ish crops taking this approach before ultimately losing the plants to blight (it’s fairly prevalent round here).  I was intrigued to see a different watering setup advertised for sale which reduced the reliance on the human.  Essentially it is a fancy plastic tank with plant pot arrangement on top and supplied with capillary matting and feed.  The water goes in the tank, the capillary matting gets poked through the bottom of the pot and dangles into the tank. Here’s a photo.

The plant slurps up water as it needs it.  All the human has to do is top up the tank every now and then.  Of course I could just buy this set up, but that’s quite pricey, it’s over £40 plus shipping.  I’m applying the same principles in a slightly more jury-rigged setup.  I bought some cheap plastic storage tubs and some capillary matting to cut up into wicks.

Future reservoir system

I might have been able to use the lids from the tubs but wasn’t sure if they would take the weight of the pot, compost, plant and eventually fruit.  I’ve constructed a lid using some long pallet slats. It will simply rest on top of the tubs.  I think I can squeeze 8 plants onto this arrangement without them being too close for comfort. I’ve drilled a hole for each pot so the capillary wick can be fed into the tank, and other holes to allow the human operative (me) to fill the tub reservoirs up.


I think I’ll be able to use the same system to deliver liquid tomato feed to the plants, I’ll just add it to the water every week or two.  To stop the pots wiggling about I’ve screwed them to the wood.


I added the plants, taking care to ensure the capillary matting was in good contact with the root ball.  That is how the plant will get its water in this system.  I’ve no idea how long it will take to drain the tubs – depends how thirsty theplants get I suppose. I’m expecting to get a couple of weeks out of each refill, we shall see.









The whole thing cost me £16 for the tubs plus pennies for a few screws, the rest was all free. To buy an 8 plant system like the one featured would be close on £90 delivered, so if it works (still a big if…) then I’ll feel pretty good about the bargain nature of my bodge.

The control for this trial is 8 other tomato plants of the same varieties planted in my normal way using grow bags and relying on yours truly to water in a not-too erratic fashion.  I’m using the following varieties:

  • Bajaja (2 in each group)
  • Sweet million (4 in each group)
  • Ailsa craig (2 in each group)


The hypothesis for this trial is:

Plants using the reservoir system yield more fruit.

I’ll weigh the fruit. I might get more fruit, and they might be larger, so weighing will be the best method I think. I should also get less exploding fruit, less bottom-end rot, both signs of erratic watering, both of which reduce yield.

I’ll be back in a few weeks with an update on the process and plant growth.