Crassula "Buddha's Temple" kimnachi

[WayneByerly]

I bought this Crassula kimnachi in July of 2013, which means I've had it almost for exactly 4 years.. It was rather small then as you can see.

Last year I built a very primitive, very basic greenhouse, and put most of my cactus and succulents in it, this one included. At the beginning of this summer, concerned that things MIGHT be getting too much direct sun--although everything has been doing extremely well--I put another layer of plastic on it ... JUST the top.

Anyway, after I put the Crassula in the greenhouse last year, it started producing offsets like mad--which pleased me greatly as it had not put out any offsets prior to it going in the greenhouse. But likewise, a number of the leaves on the bottom 1/3 have begun to turn yellow and brown, and I am very inclined to want to know why.

Am I giving it too much water (a good soak every 2 weeks or so in the growing season and then let it dry out)? Or maybe too little water? Is it suffering from getting too much sun? Should I bring it back inside where it only gets about 4 hours of direct sun through the day but 16 hours a day of 4 foot flourescent grow bulbs? This yellowing/browning of the leaves you will note only occurs roughly in the AREA of where the offsets are being produced. Is this a natural reaction to producing offsets?

O.K.--here is all the empirical evidence I can produce (pictures) for you people who (I desperately hope as this is one of my favorite succulents) will be so kind as to help me with the identification of any problems.

You can see how small it was when I first got it ... man, these guys are SLOW growers. From approximately 1 inch here to about 3.5 inches in 3 years. And another 1 inch of growth since it went in the greenhouse.

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The ENTIRE plant, showing some of the offsets and the extent of the yellow/brown leaves. Oh ... please ignore the date stamps on the rest of these pictures. I let the rechargeable batteries in my camera die and when I changed them today to take these pictures, I didn't reset the date/time. Oh ... I also replanted it this year in a mix of coir, barkfines, 1/8" volcanic rock and some worm castings. This producesa mixture that drains quickly, is light so that roots propagate easily and has SOME organic materiel for growth. The sticks (BBQ skewers) are there to provide additional support until it can grow new roots.
{{this just now occurs to me ... do these guys have an extensive root system? I can't remember. if not, and the soil in the bottom of the pot is staying wet too long, that MIGHT explain the yellowing leaves}}

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Just the top of the plant, showing how compact the leaf structure is. The brown edges that you can see in this pic ... are these natural? Or are they additional evidence of something going wrong?

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these last two pictures, taken from two different sides illustrate the rate of offset output, and the yellow & brown leaves which have prompted me to write here. The extent of the yellowing leaves are what make me wonder if this is a natural part of the offset production.

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I sure would appreciate advice from anyone ... especially someone with some experience with these succulents. I really love this particular plant, and would jump through hoops to keep it alive and healthy.