Hi gang!

I am trying my hand at citrus again...I read every post in this forum, I think....
Where I run into trouble here in MN is that citrus have a hard time for me as indoor/outdoors for many reasons...even in spring/summer. I would like to keep my new guys that i just got from four winds in my office until the new house is ready..about a year..I have navels, lemons, page, and kishu.
The office has a 9ft ceiling with flourescent lighting, and white walls. there is a corner with a NW facing 36x36 window. I plan to have the plants in a 4x4 space by the window with a supplimental 400w metal halide on for 14 hours or so.
will this produce enough light to actually grow and thrive..and fruit!
should I use a smaller or larger light? I also have MH grow lights in 175 and 250...
Albert

Al, I also have a Metal Halide (MH) Light system. The MH bulb that I use is an Agricultural Spectrum 250W bulb. The last tree I used the lamp on was a Marisol Clementine, to insure the tree received 15 hours of light each day, during the fall, winter and spring. I turned the light off every night between 10:00 PM and 10:30PM. Receiving this length of light, plus fertilizing twice a month on the 1st and 15th of each month, the tree produced 5 flushes of growth per year, every year I continued the procedure. During the night hours, I also placed silver reflective boards around all four side of the tree to reflect the light back onto the tree. When you begin the lighting, start with the MH light 18 inches above your tree. In 2-3 days lower the light 2 inches (down to 16 inches above the tree). Then again in 2-3 days lower the lamp another 2 inches so that the lamp is now at 14 inches above the tree. Continue this lowering schedule until the lamp is 6 inches above the top of the tree. MH lamps give off a lot of heat, and as I have never used a 400W bulb, I do not know the amount of heat such a bulb would emit. My guess is that you could use a 400W bulb, as the amount of light should not cause a problem, but the heat might if it gets to close the the tree's leaves. You will just have to play it by ear. Lastly, I would also recommend that you purchase a soil thermometer so that you can know exactly the root temperature. With the extra light the tree will be receiving, try to keep the potting soil (not just the soil surface) at approximately 80F (at least at 74F). Fertilizer twice a month, don't let the root system dry out, and your tree should produce 4 or 5 growth cycles per year. It helps to keep a log of every thing you do to the tree, and the dates of the growth spurts. Your tree should put on a new flush every 2 to 3 months. Good luck. I wish you and your tree the top success. Feel free to post any questions that should arise concerning your tree. The membership is always anxious to help whereever they can. - Millet (602-)

First, thanks for the very thorough reply. Wow!
Can I assume yours was a fairly good size tree? All of mine are around 2 yrs. The reason I ask, is that you were using the 250 exclusively and successfully for one tree it would seem. I will be attempting to cover a four ft x four foot patch of smaller ones. I would like to know what your effective coverage area was. BTW, I like the silver board idea o

Al, over the years I have used MH lights on various trees. When I purchased the Marisol Clementine tree I believe it was a 1 year old tree (possibly a 2 year old tree). I planted it in the ground in my Colorado greenhouse, perhaps around 2005. From the first day that I planted the tree I begun to light it, and also heat the tree's root zone by heating the soil. I was able to constantly maintain the soil temperature between 75 - 80F even during the winter months, using two heating mats placed under a 1-inch silver sided hard board insulation sheet. The tree grew very fast with 4-5 flushes per year. Today the tree is 10 feet tall and 8 or 9 feet wide. Currently it must have 100+- fruit growing on the tree. For the silver side boards to reflect the light back onto the tree, I used four sheets of 4X8 double silver sided hard board insulation. These made a 4-ft square boundary around the tree. The MH light has a white reflective hood which defuses the light at a wider angle so it had no trouble lighting 4 square feet (especially with the reflecting side walls. I kept lighting the tree until it was about 5-ft. tall and 4-ft. wide, and was producing a fairly good crop. Today I use the light mostly on young rooted cuttings, seedlings, and 1 year old true dwarf trees from Four Winds Growers. Below are a few llinks to some post on this forum at the time I was lighting the tree.- Millet (599-)

link
link

Once again, thanks for the great advice! I am determined to succeed this time. I got the plants from four winds and they were very nice indeed. I planted them in a mix of 3 parts cedar chips, one part sphagnum peat moss, and one part coarse sand...with a little blood meal. I used black plastic trays with heat mats underneath...i read air temp as 73 and soil temp as 76 with humidity at the leaf area around 50%. The whole lot is 28 inches below the 400w metal halide light. I trandplanted as quickly as i could, and watered in with 75 degree water. The excess water goes into troughs in the trays and helps with raising humidity while staying below the actual pot bottom.
Interestingly, all plants " relaxed" quite a bit over the next 4 hours with the exception of the golden nugget. It's uper leaves are curled inward whereas the lower ones are fine. I did not realize thet it was co-packaged with another tree, so i was ill prepared for a quick tranplant. Therefore the roots lay bare for about 3-4 minutes. Maybe a big deal...maybe not...i lack the experience yet to know...however it was the only tree with curled leaves. I spayed the leaves with a mild solution of fish emulsion and it seemed to help. We shall se in the morning.

Sounds like a good medium that you are using for your trees. The two most important items that the growth medium must have are good drainage, and good root zone aeration. Roots exposed for 3 or 4 minutes is not a problem as long as the roots did not become dry. With the medium you are using, over water will not be a problem. Remember, it is not the amount of water that damages a tree, it is the lack of root zone air that does the damage. The medium that your tree is growing in is open enough to retain a good supply of constant root zone oxygen. Citrus are heavy feeders so be sure not to underfeed your trees. The best of luck to you and your trees. Take care. - Millet (598-)

I am glad you like the mix, i adapted it from your suggestions! I plan to feed every 15 dayscas you suggested. Likely i will use vigoro citrus granules with a touch of epsom every now and then. I may mist with mild fish emulsion. The stuff stinks, but my last citrus seemed to love it. I did not have a sprayer handy for the gold nugget roots, but i did the work indoors, and i had the trees sent 2 day air, so the medium they were in eas pretty wet. I guess time will tell huh....