400 Watt Grow Light Question

[bigredfeather]

I recently got a 400 Watt grow light with a 400W HPS bulb. I am wanting to start my garden seeds in the basement using this as my light source. I have no experience using a grow light, but I do know that a MH would be better. I think I can switch it from HPS to MH. My question is how big of an area will this light and how high should it be above my table?

Thanks.

Spring Fever.......Oh yeah, I got it!

 

[ducks4you]

Gosh, I've grown with just a 60 watt, regular light bulb. I don't even use a 400 watt bulb to keep my baby chicks warm!! Instead, I use a 250 watt heating lamp for them.

 

[Durgan]

I recently got a 400 Watt grow light with a 400W HPS bulb. I am wanting to start my garden seeds in the basement using this as my light source. I have no experience using a grow light, but I do know that a MH would be better. I think I can switch it from HPS to MH. My question is how big of an area will this light and how high should it be above my table?

Thanks.

Spring Fever.......Oh yeah, I got it!

Most seeds about 99% will germinate without light. All they need is sufficient warmth and some humidity. After seeds sprout they need light preferably sunlight. Artificial lighting is usually a waste of time and money.

http://www.durgan.org/URL/?VMMSQ 30 May 2012 Germinating Seeds
Here is how I germinate all my seeds. The overall objective is to have high germination rates, and to have little or no root disturbance until planted in the final growing spot.
The reasoning behind this method is: The pots are of adequate size. The plastic bags keep the humidity high and they need no further water or care until germination. The bags are removed immediately upon the first sign of germination, and the pot placed in bright as possible SUNLIGHT. Most seeds only need moisture and the proper temperature to germinate. Most do not need any light. There are one or two exceptions. I have absolutely no confidence in any artificial light and consider them to be a waste of money. My germination rate approaches 100%.

 

[jackb]

A 400 watt light will illuminate a 4' x 4' garden when suspended 12 to 24 inches above the canopy. For seedlings I would place it slightly higher. You will need to purchase a conversion bulb to switch from HPS TO MH. You might look on eBay for one. I bought one last year for ten dollars on eBay and it worked fine. That said, HPS should be OK also for seedlings.

Jack B

 

[bigredfeather]

Thanks jackb!

If I try to light a larger area will the plants outside the 4'x4' just get leggy? Do you think I could rotate my tray? Reason I ask is I will have 6-8 flats of plants to start, and I know that will require a larger area than 4'x4'. As soon as it's warm enough to move to the greenhouse w/ out heat being needed, they being going there.

Thanks!

 

[jackb]

Thanks jackb!

If I try to light a larger area will the plants outside the 4'x4' just get leggy? Do you think I could rotate my tray? Reason I ask is I will have 6-8 flats of plants to start, and I know that will require a larger area than 4'x4'. As soon as it's warm enough to move to the greenhouse w/ out heat being needed, they being going there.

Thanks!

You can rotate the plants and increase the photoperiod to 14 to 18 hours. If you raise the light you will get more coverage, however, the intensity will fall off. The increase in photoperiod will help somewhat. The seedlings may get slightly leggy, but they will recover when they get in to the greenhouse or outdoors. In any event, you should get excellent results by using the light to start your seedlings. I suggest a small fan, set on low, to move the seedlings around. That will help to keep them from getting leggy and move CO2 around the leaves. Good luck.

Jack B

 

[bigredfeather]

Do you think I could supplement the area with 2 75W full spectrum incandescent lights, or is it a no-no to mix wavelengths? By that I mean put a light bulb fixture on either side of the 400W fixture.

 

[jackb]

Do you think I could supplement the area with 2 75W full spectrum incandescent lights, or is it a no-no to mix wavelengths? By that I mean put a light bulb fixture on either side of the 400W fixture.

You can, and the mixture of wave length will not matter. After all sunlight is a mixture, and it changes throughout the day, and season. Plants need light even more than nutrients. I would watch for heat build up though, try for a temperature around 85 or so. Tomatoes and peppers need more light than say cucumbers. Greens like lettuce and chard can do with less light, so keep that in mind in placing your plants under the lights.

Jack B

 

[bigredfeather]

Do you think I could supplement the area with 2 75W full spectrum incandescent lights, or is it a no-no to mix wavelengths? By that I mean put a light bulb fixture on either side of the 400W fixture.

You can, and the mixture of wave length will not matter. After all sunlight is a mixture, and it changes throughout the day, and season. Plants need light even more than nutrients. I would watch for heat build up though, try for a temperature around 85 or so. Tomatoes and peppers need more light than say cucumbers. Greens like lettuce and chard can do with less light, so keep that in mind in placing your plants under the lights.

Jack B

You da man jack, thanks!

 

[jackb]

Just a word of caution: if you decide you want MH, be sure to purchase an HPS to MH CONVERSION bulb, not a regular MH bulb, or you may damage your ballast. If it were me I would purchase the conversion bulb just to have on hand in case I decided to do some serious indoor gardening during the winter.

Jack B