Well leggy is generally a sign of not enough light. Bolting is normally a result of plant genetics and could be attributed to too little light as well. the plant thinks winter is coming so goes to seed. Spinach is a cold weather crop, but I don't believe 70 degrees is too hot. I can't speak to the arugula.
could you post a picture of your system?

This is the volksgarden running.

This post was edited by Ricksindoorgarden on Fri, Mar 1, 13 at 21:02

Do the plants spin around the bulb?

Yes the wheel takes 45 minutes to make a revolution around the light. The nutrient is pumped into the tray and the plants are soaked as they pass through. I pump the nutrient for one 45 minute cycle a day because the rock wool cubes retain the moisture well. The lamp is 400 watts and it is about 16" from the plants so I think there's plenty of light. The light is on for 18 hours a day.

That thing looks new age man! Rock on.

Well I have heard before that running air directly over bulbs can decrease the lumen output of the bulb.

You say you added the bulb yourself? How old is the bulb? How much have you used it before? Can you measure the lumen output somehow?

Leggy plants is a sure sign of not enough light

I am using a 400 watt digilux metal halide bulb and a Galaxy select a watt electronic ballast both brand new. The box the bulb came in says universal 45,000 lumens (whatever that means!) Omega Gardens, who makes the Volksgarden says people are using 200 watt compact fluorescents to grow lettuce with good results. My 3 types of lettuce are doing great in this setup.

I never heard that air passing over the lamp could diminish the lumen output of the bulb. I can't imagine the physics behind that claim!

One thing that does happen is dust clings to the inside of the 6" borosilicate glass tube as the cooling air is drawn over the bulb. I am hoping that once I'm done building in the grow room that will diminish but either way I clean the tube once a week and it is rather easy. Ironically the pop up that comes up when I sign on is for a Swiffer duster and that is the tool to make dusting the inside of the tube quite easy. (Never thought I'd say that about a pop up! )

Unfortunately I do not have any sort of light meter to actually measure output. I should be looking into getting one as I am concerned about my LED's and a light mover on another system in the room.

Any chance the length of the day signaled the spinach to bolt?

Are they leggy, or bolting?
Leggy is usually to little light which would not seem to be your problem with that bulb and ballast.
Bolting could be too hot or I was reading could actually be from too much total light(too much or too long or both) causing the bolting.
Perhaps cut the light down to 12 hours and see if it improves.
Here is where I read about too much light:
http://www.vegetablegardener.com/item/5044/why-lettuce-bolts-and-what-you-can-do-about-it
Cool system!

Arugula and spinach are cool weather crops and bolting is a sign of heat stress. Despite the air-cooled light setup, you still need air movement over the plants, or the system will trap heat. You could put a fan blowing over the plants. You could also grow the most heat-tolerant varieties you can find, or just grow different plants that don't mind a little heat.

Thanks for the replies and the link. I will try directing a fan to move the air over the plants as well and I'll cut down the time, which will save some money (the HID is the expensive one to run). I'll cut back to 14 hours and see if there is a difference.

Thanks for all of the replies.

I believe 16/8 is a pretty standard light cycle for short season crops.

Hi Rick, Welcome to GardenWeb. Could you upload some images of your set up, which may help us to suggest few things? Good Luck.

This is the view looking into the spinning wheel, it is only 3" from the wall so I will be adding a fan to help move air and cool things off a bit.

From here you can see the long rectangular duct which I had fabricated to connect with the blower to pull the air through. The flex duct that I use was too thin to be right in the aisle. I figure a 12" fan on the rafters directed down into the center of the circle will give me better air circulation.

Wow, I get dizzy just looking at a still photo of that thing!

As for arugula, here in socal where it naturalizes as a weed to a degree, it tends to germinate with winter rains, well before last frost. Right now in my garden it is in a nice vegetative growth mode. By mid-spring a bunch of it will be in flower and mostly gone to seed by mid-summer. So, more of a cool-season crop, but it does like sun.

I cut the lighting back to 14 hours a day and aimed a fan into the wheel. After 5 days I see an improvement. Thanks for the replies.

Hi rick,glad your plants are doing well now. :)

Can i ask how many inches apart are the plant holes from each other?

The plants fit into a 3 x 3 rock wool block which fits into a holder and slides into a track on the garden wheel. There are 16 slots spaced equally around the wheel that hold up to 5 plants each. With 5 plants there is a space about 1" between each cube.

Rick, did less light and more air fix your issues? I see that they improved after 5 days, but was that a long term solution? We currently have a volksgarden with a 250w CFL and we're getting leggy lettuce too at 18 hours light. I'm wondering if we need a more powerful light or if we need to cut back the light or what. Any suggestions? Thanks!

Less light was the fix that still seems to be the best way, I settled on 12 hours of daily light and I use a 400 watt metal halide. I only need the fan in the hot summer months.
Have you discovered any plants that are compact and work well on the wheel? It is tough getting new plant suggestions, Omega Garden doesn't help much and I can't find much info about growing legal crops anywhere.

This post was edited by Ricksindoorgarden on Fri, Sep 26, 14 at 19:14