our version of this – we had run out of undug beds by potato planting time, but we had a big area that we’d mulched with rotting hay. the hay was 6-10″s thick. we stuck potatoes in the middle of the hay layer, and put a row of well-rotted manure on top of the line of potatoes.
our yield was enormous! the plants were huge too. we planted very late (may) due to the mad spring, and we have just had to lift them as they were starting to get blight. but you could tell the plants were otherwise still going strong – loads of tiny potatoes on the roots – so if we’d been able to plant earlier, so as to have more growing time before the blight, the yields would have been colossal.
we hadn’t even got round to earthing them up – next year we will try using hay for this.
and slugs? our garden is VERY sluggy but despite hay mulch being an obvious habitat for them, they didn’t do very much damage to the potatoes. most of the crop is good enough for selling, and we’ll enjoy eating the damaged ones. we did find 2 big toads nestled in the hay though, so it’s clearly a good habitat for slug predators too!
all in all, very pleased with a high yield for absolutely minimal effort