You can re-pot now or any time you like. If you are going to use the same mix, no need to bare root; just fill the larger pot below and around the existing root ball. Do not fertilize for at least 2 weeks, or until you see the beginning of a new flush; the absence of fertility encourages the roots to grow in search of food and water. After the roots grow, the leaves and branches will grow; and they need fertilizer.

Are you sure it is drying out? I'd expect the initial symptoms of drying out to be wilting new growth, and foliage losing its gloss, rather than dieback at the leaf tips like that. Could it be too close to the light and getting scorched?

Or judging from what John Merr says on this old thread, is it salt burn or over-watering? http://forums.gardenweb.com/forums/load/citrus/msg1222232714318.html?22

I am not an expert, but your leaf damage really doesn't look like under-watering to me and in my experience no potted citrus (in any potting medium) which is thoroughly watered daily is going to suffer from lack of water, unless it is kept in a seriously under-ventilated greenhouse in very hot weather.

Just my opinion of course.

Are you sure the griity mix is holding water like it should?

It's possible that the mix could be repelling water in many spots causing it to dry out too often..Too, how hot is it getting under those lights? Those leaves looked tired and burnt from excessive heat..

It is almost impossible to have fertilizer damage or over water in that mix, although it is possible to under water because the mix already repeling water before you put it to use..

Did you soak the mix for a day or so before using it? Have you lifted the tree from the pot after a watering to see if you have any dry spots?

Your mix should be holding water longer than you say it does if it is functioning properly and made correctly..

If all else fails and the mix is at fault, you could soak that pot in a tub of water for about 15 minutes and then soak it for a few times after that until all the ingredients regularly absorb moisture evenly.

if you decide to to a repot, you can do it anytime. I would soak the griity mix before using it or add more turface and still soak the mix...

Mike

Thanks for the feedback. I appreciate considering other causes for this problem. The reason I suspected the mix to be drying out is that I checked the moisture with a chopstick for several consecutive days and the chopstick came out dry each time. The pot is relatively small as well - about a 6-7" terra cotta! There was some intent to keep the tree smaller by not putting it in a big pot. (keep in mind the tree is young and small as it is)

I always water to excess with a considerable amount of leachate (generally >20% of the water applied), so I don't think salt-burn is likely. Generally I water for 3-5 days with low concentration of fertilizer (~1/4 strength) and follow with a day of plain water.

I've tried fully submerging the pot in water and letting it soak 15-20 minutes, but it didn't seem to stop this drying of the leaf tips.
I haven't, however, tried lifting the tree from the pot because I assumed that the mix would fall away from the roots. Is this an incorrect assumption?

The top leaves are 4-5 inches away from the fluorescent bulbs. The fixture does give off some heat, but in general they are relatively cool bulbs (compared to metal halide and incandescent). I have several other trees that are within this range from the light - including another lemon tree that is in the same mix - and they do not show any damage. Additionally, the tree has been at a relatively constant distant for it's duration. There was an occasion on which the leaves grew too close to the bulbs (nearly touching) and they burned between the veins (see image) or at the points which were closest to, or contacting, the bulbs.

I'll move the light fixture to be further away from the leaves as a start. If this doesn't solve the problem I will repot - unless there are any other suggestions or feedback on potential causes. Thanks again!

Have you checked for spider mites?

There is another cause of leaf dehydration, especially under lights. That leaf looks like it has stippling going on.

I would be safe and check for them with a magnifying glass..If you don't have one, then treat your trees with a safe horticultural soap under the leaves just to see if you notice a difference in leaf turgidity..

It is safe to assume something is dehydrating your leaves....They should be straight out, smooth and very green.

I would for sure check the roots and the mix after a watering...If the mix falls away it's ok. That will tell you how deep your roots are or if they have even grown at all..They might still be shallow only within the first top inches of your pot left to dry out very quickly. It will tell you precisely where to check for moisture, It will tell you if the roots are healthy.
It show you any dry spots..

Like I asked before, do the leaves perk up and look great after you water? Do you notice any difference until the mix dries out?

You might consider at the same time putting it into a plastic pot to hold moisture longer or even having a mix at the ready with more turface added.

There are many things you can do to amend or fix the issue of your mix drying out to fast if that is what you have concluded the problem to be)

I transplanted my 3 tangerine trees I started from seed from a 12 OZ. drink cup to a one gallon bottomless coffee tin in May 2013. They were around 6 inches tall At the end of summer near the end of August 2013 I transplanted the trees into 5 gallon buckets and placed them under lights. They Quadrupled there size in linear growth. This spring May 2014 I planted 2 into the ground and one in a 55 gallon half drum. They did well again. The main thing you need to worry about is too much water and the soil being wet to long. This can and will eventually lead to root rot.

My biggest problem with dead plants, is I don't give them enough water for fear of causing root rot. This is why I started using bigger pots than most others. Keep in mind that citrus are trees too and if you look around at the other trees you will notice that they have spots, tears, cupping, twisting , scrunching, and malformations in their leaves to.

At least 3/4 or the leaves on my citrus are malformed by one of the above and they are still doing great. Don't worry to much. Just guard against spider mites. Be proactive in your treating for pests. They are easy to control before they get a foothold. Click link to see a tree transplant video to see how easy it is. The picture below is of my seed grown sweetlee tangerine tree. The seed sprouted 1-7-13. and the picture is on 9-30-2013. The trees are tough and can be handled with out too much worry.

Steve

Here is a link that might be useful: https://www.youtube.com/watch?v=_AkMFbhlgB0

This post was edited by poncirusguy on Tue, Sep 30, 14 at 13:05