I've been reading about ollas ( pronounced oyas, I understand). These are water permeable terracotta pots that are buried between plants and container water, which seeps out slowly. They're used a lot in countries where water is a precious commodity (unlike the Highlands of Scotland you might think). The idea is that the water doesn't evaporate as it is never on the surface and encourages good root growth. We thought they might be good for the polytunnel as the temperatures can get very hot, resulting in us sometimes having to water the ground as well as the plants twice a day, morning and evening. And believe it or not, sometimes the loch that supplies our water can get quite low at times.
Proper ollas are beautiful onion-shaped pots and are hugely expensive, in this country at least. Anyway, to cut a ramble short, we found some terracotta plant pots with saucers that fit nicely over the top, which are perfect for our tomato tubs - less than £2 for both. We bunged up the drainage hole with silicone and have put them in some of the tubs.
Of course, Sod's Law had it cold and rainy (plus a fair smattering of hail) over the last few days so it's difficult to tell if there's much difference - but it's early days yet. We have only had to fill the pots once in the last week, whereas the other tubs have been watered every other day though so I'm hopeful.
If it works we'll invest in a load more terracotta pots and saucers - I'm seeing the occasional day out in my future instead of being tied to the polytunnel.
