are ALL metal halides good for veg?

I'm looking at the Sylvania Metalarc MH bulb (below), and I see that the spectrum is given as 4200K...

I've read everywhere that optimal K is at 5500-6500K. Why are MH bulbs considered so good for vegging when most of what I see in MH is usually around 4200K? Is this still a good spectrum for veg?



Sylvania M250U/BT28 clear universal Metal Halide Lamp

• 250 watt BT28 clear bulb with mogul base
• Operates on M58 ballast
• Operating position: Universal
• Fixture Rating: Enclosed
• Inital Lumens: 22,000
• Mean Lumens: 17,500
• 4200° Kelvin - 65 CRI
• Average rated life (hrs): 10,000V - 7500H

MH bulbs are available in color temps up to 20,000k. 5000-6500k is a good full-spectrum range that has been proven to work well for veg. You can use bulbs outside that range, but you should be able to find the proper equip.

thanks for the reply burninjay,

I'm bummed cause I bought this bulb already thinking that they're all created equally... It was not very expensive either ($16).
The full spectrum MH's are about 50 bucks plus. Is this what most of you are using when you use metal halide? I never seem to see anyone mention the spectrum much, just the wattage and lumens.

4200k is still a full spectrum bulb, just has a bit more red output. At worst, you may have slightly greater internode spacing.

Cool, I'll use it then, and perhaps supplement it with a 47W 6500 cfl I also happen to have.