[mushroom]

hi,

what is the best pH for potatoes?

[WG.]

Firstly reduce the atmospheric CO2 content by 50ppm, then ...  

Seriously though, I couldn't tell you the pH of the soil in any part of my garden.  I simply lime before brassicas (to raise pH) and manure before potatoes / garlic etc (to lower pH).  Adding compost also lowers pH.

Potatoes tolerate a wide range in soil pH, but potato scab can be a problem if the pH is above 5.3.

Even then, I'd be tempted to opine that it is free lime in the soil which causes scab.

[Trillium]

All the commercial potato growing associations in Canada have tried to figure out what causes scab, and so far, no luck in diagnosis. They assume it's probably something that is in your soil, perhaps another natural element in greater quantity but even that is a guess. We get it here but it doesn't affect quality in the least, just external appearance to varying degrees. Just keep regular rotations going.

[gobs]

Loads of manure Mushy.

[mushroom]

heh. Well, "Some Bits Will Have Wood Ash" in the potato bed   for better or worse. I really must get a pH kit!