I'm not an expert, but I'm trying to grow citrus trees also. I read or heard somewhere that you need light for a longer period of time though. If I remember correctly 15-17 hours a day. I don't think 10 hours is long enough. I could be way off base, but I think your tree may think it is fall with shorter hours of light. Mine aren't doing that great, but I do still have lemons slowly growing. I have mine inside near a small window with one of the same lights you have above it on all the time. I think if I were using a better light I would be able to turn it off for a few hours a day. Good Luck!

Citrus notorious for shocking imho.

I have a 1000 watt light and my Meyer Lemon still dropped leaves when I brought it inside.

I would recommend you have a brighter light and make sure the root zone temp is above 60(Mel says 64F on the Citrus forum.)

Scott

Scottplumerias, What kind of light are you using? A 1000 watt light bulb sounds very bright. Can you provide details
Thanks.

wow, my first post on this website :)

the 60W bulb (i'm assuming it's incandescent) isn't, imho, nearly enough light. i'd definitely change to fluorescent lights, because you can keep them closer to the plant, too, without overheating it.

i recently started a citrus from a store-bought organic grapefruit. i keep it near a window to steal as much light as possible from mother nature, and also have fluorescent lighting on it since i keep it with my tomatoes. the growth has slowed down considerably, though, since i took it out of the carnivorous plant terrarium it was in, and in there it was getting light from 2 shoplights about 8-12" away for 18 hours a day.

btw, if you have a camera with a light meter that gives you the f-stop and shutter speed, there are web-sites that tell you how to convert that to foot-candles so you can test your light to see if it's bright enough. (however, i've run across one that's obviously wrong so look around.) unfortunately i didn't bookmark it.

Welcome Osuchowski! Rantoul, here.

I started several key limes last winter and they seem to be very happy under under about the same scenario as your grapefruit.

In one area of my house that has some great southern exposure I have a shoplight 24/7 because it provides some supplemental light from a higher source. The room where I keep my tropicals I have a shoplight directly above my orchids and a couple of small flourescents directly above the lower shelving units. I've also replaced one of the bulbs in my ceiling fan with a blue (?) grow light. I leave this on 24/7, but the flourecents are on a timer for 18 hours.

Cheryl

Hi Cheryl,

My southern exposure just sucks, though. I live in a "garden apartment" (total oxymoron if it weren't for the lights!) with pretty small windows, so I burn tons of lights in addition to having a humidifier. But you can't beat fresh tomatoes in December! ;)

I'm actually adding even more shoplights because my Hibiscus isn't looking that pretty and I started some more veggie seeds.

Ok, all that's probably off topic but oh well...

Peter

you could also try some of those cheap work lights they sell for 5 bucks at walmart, menards, and probably homedepot. they consist of a metal clamp, a plastic socket, and aluminum or tin reflector.

then you can screw in a regular compact fluorescent (meant for regular home sockets)--i've bought some that say they're "equivalent to 200 Watt" lightbulbs, and sure enough they put out about 3,000 lumens, about the same as a 48" fluorescent tube.

the idea i had was to get greater intensity per square foot than from shoplights, which might be beneficial for a citrus or other tropical that likes intense light. then again, maybe it's a lame-brained scheme that's doomed to failure...

peter

wow...i haven't give my citrus any real lighting *yet* this winter and they haven't really stressed much..they haven't grown much either!...How moist is the soil?

i don't really know what to do so i let the soil get somewhat dry to the touch on the top before watering. the plant is only about 8" tall now but looks healthy.

i think it would adapt to lower light levels, but i'm foolhardy enough to think i can eventually produce fruit! ;)

i recently imported a variety of 12 citrus trees to NY and use 8 foot fixutres, w/ sylvania lighting w/ a Kalvin rating of 6500 (6200 being registered at high noon on a bright sunshine day) and a CRI index of 88 out of a reading of 100 at high noon

i am having an outbreak of powdery mildew appearing on my citrus...i need a little help here !!

Google powerdery mildew and take a look @ the treatment...i believe you can make it out of milk(?)...i wasn't aware of citrus getting it...good luck

With regards to brightness and wattage...the first rule for grow light newbies...

It's never as bright as it looks! Just because it "looks" bright enough, doesn't mean it is!!

In regards to the last comment on lighting, that is very true. The light that we see is in a different area of the spectrum than those the plants require. Plants require more blue and reds, where we see more yellows and whites. Fortunately CFLs give light in those spectrums, but they need to be kept very close to the plants, so that they can absorb them, before the surrounding environment does. If you have an unheated basement or sub-floor, you may want to consider putting a piece of styrofoam under the container to help insulate it. Wood is a poor insulator, and will actually carry the lower temps to the soil, which could also trigger a fall condition for the plants, if they are set directly onto the floor.

Here is a link that might be useful: Marigolds Across America