When to add a fan on new seedlings?

I planted my seeds 8 days ago (tomatoes, flowers), they are up and about one inch tall already, made two grow light stands and have 2 four foot flourescent shop lights that seem to be working well, I want to add a fan for air circulation but don't want to add it to early, my question is when should I add the fan and how long should I keep it running, thanks.

Heroncove13,
Congratulations on your seedling babies!
Congratulations on your 4' shop light stands!

Before I address your question, I have a couple questions for you:
How close are you keeping the tops of the seedlings from the lights?
How long are you keeping the lights on daily?
How cool is the room they're growing in?
Why do you believe you need a fan blowing on the babies?

I just parced out the last of the 208 tomato seedlings I started from seeds in January...here's a pic...didn't use a fan...



This message was edited Apr 6, 2011 2:24 PM

Gymgirl, thanks for responding, you tomato plants look great, how old are they in the picture? My plants are about 1 to 2 inches from the lights, I am using full spectrum lights (I know, I am new to this forum and it sounds like, from everything I have read so far, that I did not need the full spectrum lights, live and learn, the good thing is the the bulbs were on sale so only cost 2 dollars more the regular flourescent lights). Anyway, getting back to your questions, the room where my plants are is 70 degrees, and the lights are on for 16 hours per day. The only reason I was thinking of a fan is because I read somewhere that a fan, running at a slow speed, for 10 minutes a day will do two things, strengthen the plants and provide additional air flow that will lessen the likehood of disease. Sounds like you didn't use a fan and had/have great success. Thanks again....

Heroncove13,
I have used a fan in the past, and there is benefit for using it, like you've read. I just didn't do it this time. But, I noticed I did have more gnats than I had when I used the fan, so, I may use it on the next seedlings I sow.

I used regular old shop lights, nothing special. Bought a case of cool lights on sale at the box stores, 10 for $12, so I'm set for awhile! Sounds like you're up and growing in great conditions. Oh, one thing. I have FOUR shop lights per shelf. I started with two/shelf for a couple seasons, then reset them to accommodate two kits side by side. I noticed a difference this time. Stronger seedlings from the start, and more light on the edges of the trays. Before the ones on the ends weren't getting enough light (leaning into the center of the shelf). Now they grow straight up and down!

Just a word of caution about the fan and the dampness of your pots. Just like human babies turn blue when they get too cold, your seedling stems and the undersides of the leaves will start to turn PURPLE if your babies get too cold and the soil is too damp. So, err on the side of keeping your soil just this side of damp, and never let them sit in water. Once you've watered and the top of the soil is moist to the touch, pour off any excess water. Too damp + too cold = unhappy, purple babies!

Here's a pic of some too cool seedlings. You can see the purple tinge. Poor babies!

Linda

Gymgirl, thanks for the info and pictures. For my set up I have two 4 foot shop lights, each shop light contains two bulbs. However I am limited because my plants can only go directly under the lights, I have been thinking about adding two more shop lights, I have the room and this would double my lighted space, since this is my first year with grow lights maybe I will wait till next year to duuble my space, I am sure I am going to run into other issues, thanks again, by the way how old are the plants in the pictures?

Once tomato seedlings are about 3 inches high, you can strengthen them by either brushing them or using a fan. But if you use a fan, start it very slowly and aim it at plants for just 5 minutes a day to begin with. Read more here: http://www.tomatodirt.com/strengthen.html
Good luck!

KathyWid, thanks for forwarding me the article, I think I will go the fan route.

HeronCove13,
I'm a bit confused. How many bulbs do you have on each shelf? I have four lights on eache shelf. I have four shelves.

Gymgirl, my set up uses 2 four foot shop light fixtures, each fixture uses two bulbs so I have a total of 4 flourescent bulbs. I bult two stands (one stand for each light fxture). The stands are a simple design, made out of 2x3's, the stands are 4 feet high and 50 inches wide, and I placed a card table under the stands to hold the plants. Seems to work very well, however I could add one or two more light fixtures, since the card table is wide I have space on the table that is unlighted. The card table is actually my shelf so I only have one shelf.