Do plants need to be hardened off before going into the GH?

Hi,
My first year with the GH and had a question for you experts :). I'm starting my seedlings indoors, then plan on moving them to the GH. Some of the plants will go from the GH to the outside garden. What hardening off process do I need to do? Can the seedlings go directly to the GH without hardening off, or do they only need it if going from the GH to outside? Any advice would be appreciated. I'll be doing both veggies and annuals.
TIA,
Dave

It may not surprise you, but the answer is "it depends"...

To harden off simply means to gradually get plants used to new temperatures and light conditions...

Indoors under flourescent (low) light, plants will grow large leaves to take up enough light. If you transfer these plants directly into direct sunlight (and winter sun through glass panes can be quite tough) you can shock the plants. Bringing the plants out gradually and getting them used to the higher level of light may be necerssary. Even so, plants which have grown leaves for indoors light will generally have to regrow new leaves for direct sun, so do not be surprised if the plants loose leaves temporarily.

Also if there is a big temperature difference from indoors to the greenhouse, there is another reason for you to harden off. If the indoors tempertures are 65-70F and you are moving the plants out to 60-65F there is not a lot of reason to harden off (because of temperature.. you may still due to light). If temperatures are 45-55F you may still need to harden off due to temperatures.

In any event, I would put them out for a few hours first and shade them initially. You can then gradually introduce more light and longer time in their new home.