Update-

Okay, so I fertilized it about three weeks ago. Days after fertilizing, the tree grew a ton of new leaves, and I was relieved. I thought it was out of the woods.

Unfortunately, that wasn't the case. I was on vacation for last week, and when I came back the leaves that had grown had started to yellow again. The soil was pretty dry, so I watered and feetilized again. The leaves continued to yellow. Maybe the fertilized water evaporated before it got a chance to soak in properly?

The water drained very slowly when I watered, so I checked for drainage holes. I found only one the size of a penny. I'm planning to somehow make more drainage holes with a knife.

I kept forgetting to repot. I couldn't find any appropriate sized pine bark for the 5-1-1 mix in the local stores. Any recommendations for finding pine bark?

For the pine bark, go to a pet store (or Amazon) and buy reptibark. It's used for reptile tanks. That's what I use for the 5-1-1. It lasts longer than pine fines but is more expensive. Amazon often has it on sale for $15.99.

Your tree's problem is indeed a nutrient deficiency. Fortunately, it is a deficiency that is rater easy to correct. Your tree is deficient in the element magnesium. Apply Epsom salts (Magnesium Sulfate MgSO4) by dissolving one tablespoon of MgSO4 in a gallon of WARM water and apply to the root zone. You can also use it as a foliar spray. The visual symptoms of a magnesium deficient leaf appears on the older leaves showing a green delta portion at the bottom of the leaf with the rest of the leaf being yellow. For a container citrus tree, you should apply MgSO4 approximately 3 times a year. - The best to your little tree. - Silica

If your 'soil mix' is compacted, or suffocating your roots, which it sure looks like from here, then fertilizing it will only push it to decline further because the roots are not healthy enough to utilize it or not be negatively impacted by the Epsom , fertilizer, or tap water salts that will kill them further...NO matter what symptoms you have, not just discolored leaves, but more importantly damaged twigs and branches, they can not be fixed without the proper mix even if you use the best fertilizers including Epsom Salts in the world...

Roots are the heart of the plants, first fix them and their environment, then give them what's important once they heal and can do their job properly again)

If your roots are functioning as suppose to, then your leaves should be much greener, twigs should be alive or at least healthier, and your tree should look more full, even without fertilizer...

You should definitely repot that tree. Once it is in the right mix, it will absorb all the nutrients and can recover.

I agree with the others recommendations.

Ciry

I'd repot asap, and get rid of all the debris and other moss that growing on top of your soil right away, too. It probably doesn't help the water evaporate and the soil breathe.

Once you repot in the appropriate mix (if you do a search on my history I have a step by step of making the 511 for the fist time last year, with pictures), I would start fertilizing again.

Good luck!

.

Atheen

Atheen, great advice..Please help me? Can you find the link to that thread you did about the 5.1.1 mix..I thought it awesome and I would love to safe it to one of my favorites...Thanks))))

Sure, hold on.

There you go: http://forums.gardenweb.com/discussions/3147547/repotted-my-meyers-this-morning

I'd like to actually edit the instructions on that post and insert the soaking the bark part that I never did for not knowing I had to back then. It might help someone else, you know? How long would you say I need to soak the bark before I mix it with the rest of the ingredients?

Huge thanks to everyone who replied! I'm planning to repot tomorrow.

Unfortunately, I'm leaving for boarding school on Friday and right now my parents don't have time to get the pine bark. I will plan on making the 5:1:1 next year in summer, but for now I'm planning on using a 50/50 mix of perlite and Miracle Gro Cactus Palm and Citrus soil. Do you think that will work?

Better experts will have a better answer, but personally, I'd go 60 petite/40 mix, and I'd stay away from the palm and citrus soil, it has a lot of sand if I remember correctly. Get a basic potting mix, the coarser the better, as little peat as you can find, and stay away from anything that has water retention stuff in it.

Alright, so I repotted it a day before I left for school. It's been a little more than a week, and from the pictures I'm receiving from home it's looking okay-still some yellow on the leaves, but it's not looking terrible. Some new growth is popping out-hopefully they remain green this time!

Nighttime temps are beginning to drop under 55*F-the weather forecast calls for two 52*F nights in a row, a warm night of 61*F, then back down to 50*F and 46*F. The next three nights are all below 55*F.

Should I tell my family back home to move the citrus indoors to the greenhouse? My first frost date is supposed to be around October 15.

I had room in a greenhouse, I most certainly would get them in a greenhouse before temps start dipping below 55 on a regular basis...

Okay, so I got some pictures from back home. The tree seems to be recovering nicely (yay :) )-lots of green leaves coming in.

However, I zoomed in on one of the pictures and saw something quite worrying->

Is that mold growing? o__o

If it is, how could it be stopped? Would a spray of alcohol work?

The tree is still outdoors. It's going to rain for a couple days in a row, mixed with rather cool nighttime temperatures (still relatively above 55*F). I've heard that cool temps mixed with a moist environment helps mold growth explode. Will it harm the tree in any way?

(the bags are there as a cushion to stabilize the tree)

Gold start, that does not look anywhere like the 5.1.1 mix or a porous one at all...I'm afraid that is ROT developing and unless you find a way to keep that area warm and dry, it will spread...When you re potted, why didn't you use the 5.1.1 mix?

I would not use anything but a rot inhibitor like Neem...I would also find a way to not let water touch that area...Darn, I wish you had re potted it into the 5.1.1, mix(

"When you re potted, why didn't you use the 5.1.1 mix?"

I answered that on September 6-

Unfortunately, I'm leaving for boarding school on Friday and right now my parents don't have time to get the pine bark. I will plan on making the 5:1:1 next year in summer, but for now I'm planning on using a 50/50 mix of perlite and Miracle Gro Cactus Palm and Citrus soil.

--

The soil doesn't have any sand in it. I mixed it like I said above and repotted the tree using the mixture. It drains relatively fast, but I think the wet weather coming in won't help stop the rot. Will blowing a fan directly on the area inhibit any further growth?

For the next repot, is this the bark I should use in the mix?

Reptibark 24 qts

What perlite should I get? For the peat part I'm planning to use the rest of my MG potting soil.

Thanks in advance.

Yes, that is the reptibark. Peat and potting soil is not the same. I would advice just buying a small bag - it's quite cheap. But any perlite at a Home Depot or lowes. I use this extra coarse one, but it comes in a huge bag that you do not need. Also add oscomote plus and lime.

Is this the lime I should get?

The only perlite I can find at Home Depot is the one from MG. There is another brand of perlite in this huge bag-it was either Espoma or Osmocote perlite. Is MG perlite too small or will it work anyway?

I found this on Amazon-

Espoma Perlite 8 qt

The comments seem to mention that the size is "perfect". Also- " The size of the perlite varies a bit, but there are plenty of larger pellets."

Alsp, when you said " I would advice just buying a small bag - it's quite cheap."

Do you mean buying a smaller bag of Reptibark? I can't seem to find anything smaller than 24 qts. 4 qts probably isn't enough for the size of the pot.

In any case, I could use the extra bark for my other plants :p

Thanks!

Also-for the mold, I'm planning on wetting a paper towel or cloth with isopropyl alcohol then using that to dab away at the mold. Will that hurt the tree in any way?

EDIT:

So I got a clearer picture of the mold from two weeks ago-

Now it doesn't look so much like mold anymore..I could be wrong. Could it just be lichen?

Any perlite is fine. The coarser the better, but I have many with the regular one you mention. Don't stress over that. I meant that you should buy a bag of peat moss and not use the potting soil. The 24qt reptibark is fine...better to have leftovers than run out :-)

Oh and yes, that's the lime is the right one.

Here's the tree today:

It looks so much better :D

Some leaves look a bit pale though-

Should I fertilize soon or should I just leave it alone? I don't want to fuss over it too much so that it begins to decline again.

Thanks!