Here are some pics of my six dwarf citrus trees. I have an Improved Lemon Meyer, a cocktail tree - lemon/lime, a Cara Cara Navel, a Washington Navel, a Mexican Lime and a Grapefruit tree. All seem to be doing fine except for my grapefruit which is lighter in color, curling leaves, and dropping leaves. I am very happy that my Mexican Lime and my Cocktail tree are both blooming for the first time. I have not yet had any blooms on my lemon tree or my navel trees. Hopefully, this will come in time. I brought all the trees indoor under my 48" T5 Grow light earlier this week for the winter as the temps are starting to hit below 50 in the nights. Thanks, Tim.

What colour (temperatures ) of lights you used?

It shows a missing water symptom. As you probably water this plant like the others you might check the roots for roting and the stem for gommosis.

I use a combination of 2 T5 bulbs at 3000K and 2 T5 bulbs at 6500K for plant growth and flowering. I just checked it roots and decided to re-pot it in a new mixture of CHC. Not sure why, but this tree lacks the root growth of the other trees! It has two main roots and a few smaller sprouts of roots closer to the surface area of the CHC and thats about it; however, it does not appear to be rotten at all and does have some albeit very small new growth in the root system. I will cut back on the watering of this plant and see how it goes...Thanks, Tim.

I agree with Sylvain that this looks very much like lack of water.
You seem to be using CHCs - these can dry out very rapidly and do need constant attention to avoid under-watering.

Seriously, It can't be from a lack of water, I water them weekly like clockwork and the only dry out at the top level of the CHC...the lower levels are almost always a little moist.

I have a plant that has very similar curly leaves, it almost always has done and is now about 18 months old.. it is still much much smaller than the rest that germinated at the same time. I have no idea what sort of citrus it is though, just a random pip from my lunchbox. I always thought it was like that because it was a mandarin, satsuma or some other smaller fruit variety, maybe it's not very well.

Richard

If Tim's tree has very few roots, wouldn't that affect its ability to absorb enough water even in moist soil?

2nd and 5th look like they lacking potassium

The 2nd and the 5th pics are of the grapefruit tree in question...It has gotten the same care as the rest but has not grown nearly as much. I just re-potted it in a new mix of CHC and I will monitor it closely..not sure what else to do for it.

Sylvain and Citrange are right on, and further, as was answered to your request int the PM, your tree needs MORE water, NOT LESS. Soak the tree as recommended. It is way under watered, both from the smallness of the tree's root system, and the openness of the CHC medium. The tree surely needs MORE watering. In a medium as open as a CHC medium, the root system will have all the root zone oxygen it will ever require. The best to you and your tree. - Millet (1,197-)

Another question for those of you that utilize T5 Grow lights...You can see my lights in the last photo. Do I have the lights to far away from the plants? Thanks to all!! Tim.

Tim, the closer the lights are to the plants, the better, if you are trying to keep them growing. Light intensity diminishes by the square of the distance from the source. Halving the distance will multiply the intensity by 4. The intensity of grow lights is very much less than sunlight.

Of course if you want them to go dormant you may not want so much light.

I would recommend that if the trees have not been previously lighted, to start the lamp at a higher distance above the tree, and then move it down a little at a time ( once every 2-3 nights) until it is at the proper distance. I normally use a HID. - Millet (1,196-)