Evaldas, Danero is not using bark he is using CHC. Denaro, the few bottom leaves your tree is discarding could be, as you wrote, from low light. However, it could also be due to the flowering. One of the highest leaf drop times for citrus trees is during flowering. - Millet (702-)

By the way, danero2004 how long did it take to turn this tree
into this tree ?
It's actually very beautiful, I keep looking at it, I hope my trees will look like this...
Do you grow them in 100% CHC? Or mixed with peat?
What is that white spring in the first photo (in the pot of the tree)?

But I doubt that my problem is the bark in my substrate, because my Eustis Limequat is growing in the same substrate under lights (you can see it in other topics) and it has dense leaves, pointing upwards. Except they're a bit smaller.

Well the trees are in some "CHC MIX" of my own , actually they have
60%CHC
30%Coconut Fibres
10%Spaghnum moss
10%Perlite


the first picture is from May 2010 and the last one is from Feb 2011

I grew some in Pine bark but it didn't worked as it did in CHC , not even close to.(the first picture is with bark and some chc left from other trees but now it is in what mix I did)

I also tried some mix of 50% cactus soil with 50%perlite , and this works as well very good.

I've noticed that if the holes in the pot are not touching the table and they are placed on something that does not cover them, this does a lot to the tree meaning that the mix is more breatheable.

Do you mean such sphagnum moss?

Yes , I read that keeps the PH level right to the citrus need

Evaldas, I've heard you say your mix is in bark chips and peat, the same as the original potting soil. Unless you get the soil from the original nursery (as suggested earlier) your mix probably doesn't have the same properties.

Although the ingredients of the mix are important, as Ryan mentioned the particle size of the chips is a very large factor determining how much water is stored inter- and intra- particles, aka porosity. The spaces between the particles not only determine the amount of water available to the entire canopy (what you are concerned about), but inversely how much oxygen is available.

One last piece of advice: relax and let your plant do it's thing. After you've had it growing for a couple years, without stressing or killing it, then look into how to optimize it's environment. You'll have learned a mountain of knowledge from experience getting it to 2 years old, to which you can then hone that experience into expertise.

Getting a containerized citrus tree beyond two years old is a feat that a grower can be proud of. The average container citrus tree lives less than two years from purchase. Unfortunately, many are killed by the grower in the first year. This is especially true for the first citrus tree that a hobbyist purchases. It is a lucky tree that the owner finds a forum such as this one. - Millet (686-)

Turgor pressure is something that happens to cells due to osmosis, in hypotonic (when salt concentration is lesser in the environment than in the cell) conditions. Oxygen has nothing to do with this.
Root rot is caused by a bacteria, - I'm saying this because, C4F, when you started writing about oxygen I got the impression that you're telling me that I may get root rot, because someone is "gossiping" that root rot is caused by the roots having no oxygen. My problem is not overwatering: as I said, in summer when it had been 100F degrees here I watered the tree too little, part of the roots dried and there started being an inequality between the surface space of the roots and the surface space of the leaves, making the roots unable to supply enough water for the leaves, thus making the turgor pressure not enough to make the leaves stand upwards.
Plants like being in hypotonic conditions.

Oh, boy, here we go again...
New tree, same problem...
So I got this tree a month ago. I checked the roots, and decided that there is still space for one growth flush and decided not to repot it yet, so I left it in the original nursery soil (to me it looks like it's very good soil, because it dries after about 3 days after very thorough watering, it even looks somewhat like a peat-less substrate, containing mostly bark), the soil that it had grown such beautiful leaves in the nursery.
So sure enough about a week later a new flush starts. First it seemed like it was going smoothly. All this time I was fertilizing 200 ppm, with a 6+4+6 + trace elements. And I watered the tree with Epsom salts solution right after buying it.
But then here what happened:

Long stems, leaves not standing up, not warping inside...
What is this? Light deficiency? Fertilizer imbalance? Fertilizer to light ratio imbalance? Too much water?
I've been watering it with 1l (0.25 gallon) of fertilizer solution, even though it's only a 15cm diameter pot, its capacity is only 1.5l (~0.4 gallon). So is it much of liquid?
Look how beautiful and compact the tree was:

If it is light deficiency, then is it better to grow it under lights? We do have half less sunshine throughout the year where I live, than for example in places where citruses grow naturally. We have about 1400 hours of sunshine a year, as opposed to Lisbon (Portugal) having about 2800 hours.

I'm so going to rip off these shoots...

I found:

"Repeatedly, the differences in plant growth were a consequence of the amount of phosphorus supplied to the plants, not the form of nitrogen. Going back to the original question, “Does ammonium-nitrogen really cause plant stretch,” the answer would have to be no. Differences in plant height among the many fertilizers varying in ammonium-nitrate proportion are controlled by the phosphate — low phosphate levels result in compact plants, high phosphate levels result in tall plants.

Fertilizers with high proportions of their nitrogen in the nitrate form typically contain little or no phosphate, resulting in compact plants and leading to the incorrect assumption that nitrate nitrogen causes compactness. Fertilizers with high proportions of nitrogen in the ammonium form (33 percent or more) invariably contain high levels of phosphate. These fertilizers yield the more luxuriant growth to which we are accustomed and result in the belief that ammoniacal nitrogen causes stretch.

Thus, if compact plants are your goal, you should limit the amount of phosphorus applied to the plants; conversely, if full plants are your goal, you should apply fertilizers containing the appropriate levels of phosphorus."

I like the way you answer to your own questions.

Maybe you are worrying for nothing , just let the tree follow his instincts

Off topic , where do you buy your trees from citrusplants

Me too , they had some problems , and are a little smaller than those from citrusplants.

Thanks

If you're growing citrus on a windowsill, do you need to rotate the plant when it's growing new leaves? If yes, how often and how many degrees?