Hardening off is mostly a change in the surface cells
of the leaves and in the cells of the stems. It is not something
that you can see without a microscope.
Nursery plants have a few differences. They have more
light when they are growing after first sprouting. They have
nutrition that aids them in growing thick stems and leaves.
The temperature in greenhouses is adjusted to what is best
for the plant at that stage of growth. Some of the plants have
a growth retardant sprayed on, so that they are older than
the height of the plant would indicate.
They may or may not be hardened off. Growers in Florida
have reported sunburn on plants that were sitting outside
under a screen when they were purchased and transpanted
into a garden that got 12 hours of direct sunlight. They were
hardened off against the wind (the stems were thick and sturdy),
but the epidermis had not undergone sufficient hardening
off to withstand all day sun. (Leaves can actually get windburn,
too. People in the North American great plains and southwest
sometimes see it. Symptoms are similar to sunburn.)
__________________
--
alias
|