Once the plants get a couple of true leaves, I take them out of the propagation domes and place them under the lights. They toughen up in about a week. Then I transplant them, and move them back under the domes for a week or two until they get established in their new pots. Then they get moved out of the propagation domes again, and either under the lights or in the unheated greenhouse, depending on what time of year it is. Losses with this method are almost nil, even with little prima donnas like fringed Gentian.
SW Washington state, 600 ft. altitude
From Chris: "The relay contact rating in a Normally Open setup is 16 Amp @ 120 Volts, the load is 8 x 60 Watts: 480 Watts / 110 Volts = 4.3 Amps
Yet for some reason the relay contacts would occasionally get stuck in the closed position and not de-energize the system resulting in the system overheating several times. They replaced the unit free of charge, but even the replacement unit did the same thing."
Maybe the problem was inrush current. When you first apply power to an incandescent lamp, the current is 9 - 15 times higher than the rated lamp current. That can weld the contacts on a relay. http://www.powerbox.info/SSL/inRushCurrent.asp
One way to fix it would be to divide your incandescent circuit into two parallel paths with half of the lamps in each one, controlled by two separate relay contacts. Now the inrush current is half what it was before.
Another way to fix it is to use an inrush current limiter. http://www.ametherm.com/inrush-current/?gclid=CKiv0ceSirUCFYF7QgodGjEA4Q This has a high resistance when it's cold, and a low resistance when it's hot. So it's just the opposite of the lamps.
Another way to fix it is to use a proportional temperature controller. I really like this, but it's expensive. It will vary the power to the lamps to keep the temperature constant, as measured by a thermistor or some other sensor. This means that the lamps won't get turned completely on and off, which greatly reduces their life and causes inrush current.
Another thing that can burn relay contacts is arcing when the contacts open. This usually only happens if you've got an inductive load. This can usually be solved by using a surge suppression device, like a MOV: http://www.digikey.com/product-detail/en/ERZ-V14V201CS/ERZ-V14V201CS-ND/...
It is to bad there is no continuation on this topic, looking at all the seed starting chronicles, it would be nice to see how everybody is germinating and root cuttings, what do you use, like lights, shelves, greenhouse, cold frame, etc.
I do a lot of seeding and cuttings under lights and in the greenhouse, and will get some pictures posted of my setup in the next few days.
I will try to add a picture as this is the first time adding a picture to a post.
My setup is very much like yours - a wood-frame shelf system. Looks like yours is much bigger though!
The bases of the shelves on mine are sheets of anodized aluminum (not that it matters to anything). A difference with my setup is that each shelf has two four-foot fluorescent light ballasts suspended over it on chains from the frame of the next shelf above; this allows the lights to be lowered down to sit directly on top of the plant trays, and to be raised as the plants grow.
I'll try to add a picture, though it's not so terribly photogenic! ;-)
Edit: Here's one.
Looks like you have a lot growing! It would be great to hear about your germination and growing efforts, either in this thread or in the Seed-Starting Chronicles thread.
Thanks for posting!
Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm
Very nice looking structures Arie and Lori. Obviously very successful ones too. What lights do you use?
53.69° N, Dedicated to West Coast Fritillaria, plus three other members of the subgenus Liliorhiza. I grow other Genera, as time permits !
I use T5's 3 in a row and 6 for each 8 ft of shelf. I will do a reading as per foot candles and post it later. I have enough room for 72 flats there are 2 rows of them.I also use it for growing some geraniums, ivy's, fuchias etc.for my summer planters outside
My grow room is in the basement, and is build out of 2X3 pine lumber. the shelves are 1/8 inch thick white recycled greenhouse polyethylene.
Lights are 54 watts high output sunblaster fixtures, purchased whole sale from a B.C. Canada company.
I have 3 lights in a row and 6 per shelf each shelve is 24" X 96" the lights give me about 500 foot candle at the plant height.
I do not have them adjustable, but my shelves are 17 " apart, and if I want more light I just put a couple of empty flats underneath the seedling trays.
I loop together 6 lights and I can have 24 lights on a 15 amp circuit, so enough for 4 shelves each shelve has its own receptacle.
Some one has to help me, as I can only post one picture per reply, so Lori please help me, as I took a lot of pictures from my grow room and greenhouse.
I have the capability to use heating mats, but found that I was getting enough heat from the lights below to maintain 68 -70 F at night and about 60 F during the day.
My lights are on for 16 hrs and because the nights are off peak rates I have the lights on at nights.
This is a picture of my timer, Intermatic 24 hr timer and beside the timer is a a thermostat , if I want to use a heating mat.
The timer is capable of about 15 amps so enough for one bank of 24 lights.
When you hit "Reply" to this message, scroll down in the page to Embedded Images. After you Choose File and then hit Upload and then Insert (to show your photo in the text box), you will see that another "Add new file" box opens underneath the one you just used. It works exactly the same as the first one. So with each photo you add, another box opens in Embedded Images to let you add another photo. I don't know what the limit in number of photos is.
Hope this explains it.