[Rangerkris]

Cat litter trays with some water in the bottom works well to. We have lots of bright colours from the £1 shop and they do just the job.  11 three inch pots to a tray help save water too i guess as the drips get reused.

[stompy]

I think the main pproblem is from evaporation rather than the plant using it!

I grow my mellons in 12" pots in growbag trays with capillary matting and have to fill them up about twice a week in mid summer.
Im thinking of covering the top of the pots with white plastic so the plant can grow through a hole in the middle and also covering the tray with a white plastic sheet to also try and stop evaporation.

I don't see how a plant can use so much water, so as i say i think the water usage is more down to evaporation and covering would be the best bet.

Well this is what i will be doing this year 

[Paul Plots]

Cat litter trays with some water in the bottom works well to. We have lots of bright colours from the £1 shop and they do just the job.  11 three inch pots to a tray help save water too i guess as the drips get reused.

I luckily picked up some half-price grow-bag trays from Wilkos so they are huge. Each holds several full-size seed trays and makes watering in the greenhouse/conservatory so much easier.... no dripping / run-off all over the place and a reserve of water should the plants begin to gasp.

[pink aubergine]

Capillary matting works well. I used to visit a freinds greenhouse and top up a large reservoir once a week. A capillary matting wick joined up the matting with the tank of water. For this to work the soil at the bottom of the pots has to be in contact with the matting so flat bottomed pots or seed trays with soil directly against matting. So no modules in a seed tray for instance. The pots of soil need to be wet and then they continue to draw up the water from the matting.