I have an eight foot portable FlowerHouse greenhouse I was given as a gift. The material is translucent so while light does get through it, it is considerably filtered. I'm wondering how this works. I've had seedlings growing under 16 hours of daily warm/cool florescent lighting since February. It will soon be time (temperatures permitting) to pot them and try out the greenhouse. Will enough sunlight actually get through this material? I realize it must or the contraptions wouldn't be on the market but I don't quite understand why they work. How come too much distance with florescent lighting can make seedlings get leggy yet filtered sunlight is apparently not a problem? Do plants not get leggy after a certain seedling growth stage, or what?
I'm also wondering how cold the nighttime temperature can be inside the greenhouse before the plants would be damaged. (I'm in Minnesota -- zone 3b.) Some of my seedlings (especially the Dahlias and Strawflowers) are getting very large and hogging up the florescents so I need to get them out of the way, plus I have Round 2 of seed sowing coming up soon. Thanks in advance for any info and help you can give. This has been such a helpful garden site.
Using a portable greenhouse
Michael, I also have a portable greenhouse. Each year I normally get it set up around mid April. By that time my seedlings which I have started in the house under florescents are well on their way. They do just fine in the gh. My zone is 5, bordering on 4. I don't know if yours will be ready for the cold that soon because of your zone. However, I do think the Dahlias should be ok. I am assuming they are tubers and in fairly large pots? I don't know anything about straw flowers.
I have never used any kind of heater in mine because the instructions say not to. However, others have told me they do with no problem as long as you keep it away from the plastic and not too hot.
Hope this has helped a little. Jeanette
Thanks for the advice Jeaneete. Actually I started the Dahlias from seed but I have tubers on the way through mailorder (I hope) so I'll have the all the more of a problem when they arrive. I CAN move them into the garage at night (I did this last year) but I think the key questions I have are (1) how low can the temperature get in the grrenhouse oro garage before I have a problem, and (2) just curious why the filtered light of the greenhouse doesn't make them get leggy. The parger pors you mentioned are a good idea because I assume you're thinking about insulation for the roots?
I think the reason the seedlings won't get leggy is because sunlight is way, way stronger than any fluorescent lights you've been using, and even though the plastic isn't totally clear, it's been designed to allow enough sunlight to come in.
I can't help you too much on how much cold your seedlings can take, but if you're moving them from indoors to outdoors in the greenhouse you need to do it gradually--the temperature difference and the increased light can both be too much for them if you move them from 24 hrs a day indoors under lights to 24 hrs a day outdoors. I would start by taking them out there for a few hours at a time, then bring them back in, then gradually increase the amount of time they're spending outside until they're out there all the time.
I don't think Michael had them on 24 hours of lights. Most people put them on timers and only have them on for about 16 hours which is about the same as the natural of being outside.
Yes Michael, I was thinking of the mass of the soil in the larger pots. I don't know that anyone can tell you about the lowest temps because there are so many other variables such as humidity, cover, etc.
Such as water pipes might not freeze at a low temperature, however if there is outside air that same temperature blowing directly on that pipe it will freeze. Guess I am not making myself clear.
Maybe I am just confusing the issue. sorry.
Sorry...didn't mean 24 hrs of lights, I really meant 24 hrs of indoors, and when they had lights it was fluorescents not sunshine. So my advice still holds about adjusting them to outdoors vs indoors and sun vs fluorescents. Lights do not have the same intensity as sunlight, doesn't matter how many hrs a day you have them on, you need to adjust the plants to real sunshine gradually.
Thanks again Ecrane and Jeaneete (and hopefully thanks in advance to others). Jeaneete - you're not confusing things at all and the help is much appreciated.
More on this from me... I'm realizing that I am going to have a delay in getting these puppies outside and the larger plants just HAVE to be potted and moved from under florescents to keep the smaller ones exposed to light, so...
I do have two large picture windows that get afternoon sun, but it's off and on because of tree shadows. I'd guess the windows will allow about 6 -8 hours per day. How bad do you think it would be for the larger plants if I potted them and let them rely on only the window sunlight between now and whenever it warms up enough to get them into the greenhouse (maybe 2 weeks)?
As always, thanks in advance for your thoughts. Michael
I think they'll be OK--you may want to try the same thing that I suggested before about exposing them to that light gradually, even the sunlight through the window could be more intense than what they're used to, so I'd let them have an hour or two of sun then pull them away from the window and gradually work up to leaving them there for the whole time. It really depends on how strongly the light is shining in though, if it's not that strong then they may be able to handle it right away.
Good point, ecrane and thanks for the reply.
They have actually been in one window all along, but under florescents that turn on before sunup and go off around midnight, to ge them 16 hours. The light fixtures block out som eof ht esun but they have definitely been expposed to the sun coming thru that window. So they have had some sun exposure from the beginning.
Instead of moving them in and out of the window I think I would find something to hang on the window if it got too bright. I guess I am lazy, but if you have a lot of plants that could be a lot of work. What about a film like they use for sunshade? Do you have any kind of store handy that would carry something like that? Your larger stores like Farmtek etc. carry it.
Not only a lot of work, but I would tend to make a mess of at least a few. LOL
Jeanette