I don't have a cold frame, but wondered how much hardening off is needed for
plants that have been in an unheated greenhouse with the door wide open day
and night?

Surely its no warmer in there at night than the night air itself?

In hardening off temperature, very often, is of the least concern. Sun and
wind, I believe, are the two more things of importance to be concerned
about.

Some put the plants outside for a short while the first day and progress
from that point. A preferred method is to cover with a floating row cover
which reduces the sun 'effect' plus cuts down on the wind.......leave them
out all day from day one.(wind burn is as bad as sunscald). The floating
row cover allows around 90 per cent of the light to penetrate so growing is
not effected. Mine are usually left under cover for three days or so and
then ready for full exposure and planting.......HW


I don't have a cold frame, but wondered how much hardening off is needed
for
plants that have been in an unheated greenhouse with the door wide open
day
and night?

Surely its no warmer in there at night than the night air itself?