I don't have a GH (yet - hope to by this fall) but I would move them as soon as it is warm enough. I group sow my seeds and then transplant when they get about 3" tall. If I have my GH, that will be when I move them. In fact, if it is warm enough, I'll germinate them there.

Mike

All of our seed starting is done in the GH but this time of year we still have to provide supplemental lighting, even in the GH, to keep them from getting leggy.

The natural light, even on sunny days, just isn't intense enough nor enough hours in the day yet for it to be enough. So they get GH light from 6am-4 and then supplemental lights form 4p-12 mn on timers.

Dave

digdirt, do you move your plants or do they partial shading from your lights? are you using plain old flourescent shop lights?

I just moved out seedlings, but maybe I should move them back under the lights when the sun goes down for another few hours. what are the commercial growers doing? surely they don't have grow lights do they? wouldn't that be really expensive?

Mostly plain old fluorescents, same as most the other GHs in the area use far as I know. Ours are rigged suspended over the tables that line the walls and just lower down on cables when needed and pull up out of the way when not. We have 60 degree incline on the roof so the lights shading the plants isn't a real problem.

Dave

I don't have that same view as Dave. My GH tomatoes have been getting plenty of natural light; after all we just had the vernal equinox. The main problem you will have by moving plants now is that daytime sun is hard on the house grown plants and they will need hardening-off at this point and not so much when they move to the garden.

Mine are loving the GH environment, but I wanted to give you a few ideas as to the whens and whys in my situation:

First, you need to figure what heat costs are going to be to keep plants warm in a GH. I guess I got less money to burn than most because I keep plants in my house until I run out of space- I still have over a thousand tomato plants waiting for a few overcast days to make their move. Plant size doesn't become as much of a factor as the weather moderates for me.

Also what is your in-house setup like? Are the plants an inconvenience? Many people wouldn't want 12 shoplights in their living room as I have now. There also comes a time when there just isn't enough room. The 300+/- tomato plants in my GH are all in qt. pots and tomorrow they will go in the ground of another greenhouse because I'm running out of room even in my benchtop GH. I've been waiting too long for this cold spell to end. Those tomatoes are setting fruit.

One big factor to consider is the time you have to provide the extra immediate care after moving plants to a potentially stressing environment. You'll need to monitor the temperatures more closely than in your house and probably water more often as the plants dry and wilt more quickly in full sun. For me the care extends into the night to tend for a woodburner. Often I could get by with one loading in the middle of the night but with temps in the teens lately I need to fire hotter and set my alarm for more trips. I wasn't making those trips three weeks ago when all plants were in my house.

So my reasons for moving when are not as well defined as others but if you keep everything in balance you can usually end up with nice plants regardless of when you move them.

bmoser raises some excellent points jamie that need to be considered before the move. Heating is a problem right now. We had 4 nights last week in the mid-50s and then 3 nights that we had to heat. Tonight it is 60 in there but it looks like tomorrow night may be another heating night at 35.

And what is your daytime cooling set up too? Costs there? Temps in the GH jump from one extreme to other this time of year - easy 80+ in the day without the exhaust fans running and 40's at night.

I should have thought to mention that before. Sorry.

Dave

these are great things to thing about, thank you bmoser & Dave!

I think my toms are ready to stay in my gh and i'm getting ready to pot up today.