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(Edited to add more detail and an update at the end)

I have a small Eureka lemon tree that is few months old, and is currently showing signs of weakness that are worrying me. In more detail, some time ago it was withering: following this question, I moved it to another pot with drainholes and changed the soil, after which it started making new leaves (while the 3 it had before, probably dead, kept on withering).

But now, for a couple days its new leaves have started pointing downwards, and folding (picture below). This looks quite abnormal to me (isn't it?), and I have started worrying: what is wrong, and what can I do?

enter image description here Rk: the big leaf behind is one of the 3 from before it got better, and probably dead. The other ones however are new, and for instance the small one at the top is folded...

enter image description here

(Too much water? Not enough? Too cold? The pot is inside, next to a window pointed East.)


Edit: after a few days trying to give it more sun (moving it to a South-facing window whenever possible in the afternoon), it does not have improved, far from it:

enter image description here

(the picture was taken this morning, just after I watered it)

Also, in case this was not clear: the transplant was 3 weeks/one month ago, not a couple days. Now, not only the leaves, but also the stem is getting brown and dry. I am really at a loss, and am afraid it is dying quite fast.

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It is probably suffering in part from transplant shock. Give it some time to adjust.

Also, make sure you are not over-watering. If you stick your finger an inch or so into the soil, it should feel cool & damp, but not soggy. Let the soil dry to this point, but not completely dry & then saturate when watering. Wait until the soil has dried to the point of being only slightly damp again before watering again. For a plant that size in that size of container, this may be only once a week, but you'll need to test it out.

In addition, its light green color (as opposed to a healthy dark green, indicates that it is not getting enough light, try placing it in a south facing window if you can, or under a grow light.

  • Thanks.. I will water it a bit less, and am moving it to a South-facing window every afternoon. I hope it'll help it recover... I'm not clear why the transplant shock happened 2-3 weeks after the transplantation, though -- is there an explanation? (the past few days before it happened have been colder, and much cloudier than usual... could that have played a role?) – Clement C. Apr 14 '16 at 18:49
  • I'm afraid it's still getting worse -- I have tried to give it more sun, but the remaining leaves are still getting folded and looking dry, and the "trunk" getting from green to brown-green. I'm at a loss (how long should I expect to wait before an improvement appears, if any? And how come the transplant shock was "delayed" for 2-3 weeks?) – Clement C. Apr 17 '16 at 12:46
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Did you see what Escoce commented on your original question here , about transplanting it? Can you remember what the roots looked like when you transplanted it? It's possible there weren't enough roots for a transplant so it might die whatever you do now

  • I don't fully remember whether it had only one taproot (it's very possible), but in this case (rotting taproot to begin with), would it have been possible for the tree to first get better and grow new leaves, before getting worse once more? – Clement C. Apr 17 '16 at 22:14
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+50

Droopy leaves is the loss of turgidity which occurs whenever water is lost by transpiration faster that it can be resupplied by the roots. This will happen when the soil is dry. This will happen when there are few active roots. This will happen when roots are dying because they are drowning and cannot get the oxygen that is necessary for the metabolic processes of life. Sick, damp roots are also a good target for phytophthora, commonly known as 'root rot'.

So you repotted after it was failing in a pot with no drainage and it perked up, then began declining again. Possibly it contracted root rot. When you repotted it would have been a good idea to dip the roots in a solution of 2 tablespoons 3% hydrogen peroxide in a quart of water as this would have killed any such infection. But this solution only acts on an existing infection. Possibly root rot is a recent development. You can simply pour this solution into the current planting as a root drench.

Now the issue is that the plant undoubtedly has serious root troubles. Photosynthesis is required to recover the roots from the damage of repotting and/or death by drowning. But you have a situation in which it clearly is desiccating - that is what the loss of turgidity means. Putting it in full sun is exactly the wrong thing to do as it heats the leaves and makes them lose moisture to the air even faster. This is why the stem is now withering. The leaves needed to be in air that was as close to 100% relative humidity as possible!

You should have covered it with a plastic bag or a plastic bottle with the bottom cut out so that you have it in a little terrarium which will have high relative humidity. Then it should be in shade so it doesn't cook. A lot of photosynthesis can occur with just indirect sunlight.

If your tree simply had yellow leaves, inadequate sunlight might have been a possibility, but not with lost turgidity. When root cells die for lack of oxygen they produce a signalling compound that goes into the xylem stream. When it reaches the foliage it is converted into ethylene and causes the foliage to look like it does before it is shed (yellow, but sometimes orange-red in some species).

In other words, yellowing, droopy foliage = roots are dying! #1 stop watering, #2 put it in shade and, if it doesn't quickly recover turgidity, in a humidity tent and/or terrarium.

Now you should find another plant and try again (i.e., get back on the bicycle) because this one is certainly going to be dead if it isn't already. On you next try, don't water until you see the foliage start to droop - it will recover normal turgidity within an hour or two at most. Learn how the soil feels right after you water and just as the plant loses turgidity. Practice until know when to water by the feel and look of the soil.

You will do better with the second plant because you have this unfortunate experience and should now understand what the signals mean and know what to do if you ever see them again.

Plants are fairly simple. They make themselves out of carbon dioxide and water via photosynthesis in the leaves. They get water through their roots. Water is drawn up the plant by evaporation from small pores on the leaves (transpiration). Every living cell in the plant must get oxygen to live (oxygen is a byproduct of photosynthesis).

... not meaning to be overbearing.

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If your plant isn't already dead, what you could do is remove it from the soil, and wash it all off the roots. If any of the roots are rotten, cut them off. Then suspend the roots in a hydroponic solution with an air stone to provide oxygen. The oxygen will prevent the roots from rotting further, and you'll plenty of oxygen and water for the roots. You may need to cut the dead stem off as well.

I have not done this to dying plants, but I have taken very small tree branches and germinated roots from them this way in my aquarium. And here you're starting with some roots.

  • Thank you... I reckon this is the last thing to try (I am currently waiting a bit to see if after some hydrogen peroxide, as Jim Young suggested, there is any difference )... – Clement C. Apr 24 '16 at 13:41

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