"michael adams" wrote in message
...

"Gilly" wrote in message
...
I'm growing Nadine potatoes in those large black plastic potato bags
(sort
of like heavy-duty, short bin liners).

This is the first time I've ever grown spuds. The soil is now up to the
top
of the bags, but there's loads of tall stems and leaves above the soil.
They're just beginning to show flower buds.

Do I simply leave them and dig around when I want the potatoes, or is
there
a correct time to harvest?

Thanks.



Without being whimsical, or stating the blindingly obvious, the
correct* time to harvest is when the potataos are big enough to
prepare and eat - the normal recommendation being when they're
the size of a hen's egg. This is usually once the flowers
have begun to open.

i.e the earliest feasible time.

The size of the tops isn't necessarily any guide, as this
is dependant on the amount of nitogen given. ISTR having too
large a top can be regarded as a fault in cultivation, the
ideal being a balance between energy going into
the tops and the tubers.

Providing the tubers aren't green from exposure to the sun - oxalic
poisoning - they're edible at any time. The only difference is that
with main crop potatos intended for storage, the skins need to be
fairly tough so as offer protection. And so they're left in the ground
both to increase in bulk, and so as to allow the skins to thicken.

If you grow new potatoes in pots rather than plastic sacks
its quite possible - providing the soil ball holds together
to gently tip the lot out, remove the largest tubers,
fill the gaps with fresh compost and replace the lot in the
pot. Its isn't necessary to rip the whole root system
apart.

Its also possible to reach down the sides of the container
between the wall and the compost to check the size of the tubers -
although contrarily, the largest tubers are often in the centre
of the plant.

Indeed, some people prefer to ferret around the roots by hand and
pick off any potatoes that they feel are ready, and leave the smaller
potatoes in situ until they get large enough,

Andy.