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A friend has just given me an Aloe Vera with pale brown tips. Different sources have lead me to multiple non-conclusive possible causes; mainly: pests, etiolation, wrong type of soil or overwatering...

"The Guide for House Plants", for example, warns that brown stains and seeing insects are a sign of pest or disease (I saw a small insect that looked like a black aphid but haven't seen it again)

On the other hand, the post "Why are my aloe leaves turning white and brown?" here in Stackexchange, points to etiolation as the cause of this, mainly because the center steam is somewhat pale. Yet, in my case, the pale part is mostly covered by the soil.

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Moreover, the soil of my plant looks dark and peat-like rather than "desert-like" (which would drain faster), and it also looks pretty soaked. My friend told me she watered it yesterday and that she did it about each 3 weeks (when the soil looked totally dry), pouring about half a glass of water into it. It doesn't sound enough for a 20cm radius pot (near 8 inches) but I could introduce my finger almost through the bottom and it is all wet. So it might have been overwatered... (?)

I'm not able to reach a conclusion and obviously the treatment for each of the causes would be different... Is there any way to nail down the cause?

  • It's possible the soil is too acidic and thus has too much manganese available to your plant. The opposite is also a possibility. Have you tested the PH? If so, what is it? Peat moss is very acidic. I'm not contradicting the overwatering and drainage ideas. I'm sure improving drainage will probably help. – Shule May 4 '16 at 6:52
  • It's possible that the plant is stunted (stunted plants don't always drink much water; the same is true to a lesser degree for younger plants). I would give it a lot more light, if possible. Light encourages faster growth, which should encourage the plant to drink more water. – Shule May 4 '16 at 6:58
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Based on the plump, browning tips on the leaves, this initially appears to be classic aloe over-watering response. BUT, once every three weeks isn't necessarily an unreasonable watering schedule for an aloe, if the soil is appropriate. As you have correctly observed, the soil is a very dark peat-based soil. It holds water very well and drains out slowly, which is the exact opposite of what an aloe needs. The treatment for this is going to be re-potting into a lighter, free-draining soil appropriate for a cactus or succulent.

Insect damage is unlikely, the black insect you saw is probably a fungus gnat that is feeding on fungus in the damp soil. They're harmless, if occasionally annoying, and they won't stick around once you change the soil.

Etiolation might be possible given the uncommonly yellow tint on the new growth, but it isn't the main problem. The paleness under the soil-line is natural, chlorophyll makes plants green, and plants don't make chlorophyll below the soil.

  • Awesome answer @GardenerJ. I think I'll put it for short periods of time on the window sill, even outside so that it has more light sun than usual. The idea is to dry it faster so that I can change the soil as soon as possible... Thanks! – Martin May 3 '16 at 12:24
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    Beware that sudden exposure to more light can turn the whole thing brown (BT, DT) - ie, the exact opposite of etiolation - sunburn. – Ecnerwal May 3 '16 at 15:36
  • mmm, yes @Ecnerwal thanks... Actually I can't make my mind about it, but I think this deserves a new question which I'm going to post now... – Martin May 3 '16 at 16:24
  • Posted it here: gardening.stackexchange.com/questions/24475/… – Martin May 3 '16 at 17:05
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I suspect the problem is drainage - are there holes at the bottom of the pot ? If not, the plant is most likely sitting for long periods in wet roots, which it would not like.

If the soil is heavy, that would not help drainage either - but the color does not necessarily tell you there is a problem.

  • yes there are holes at the bottom, but I'll change the soil or mix it with river sand and/or something else that is not peat as soon as this one dries... Thanks to you too... – Martin May 3 '16 at 12:28
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What kind of water do you use? Is it city water from the tap? Too many salts, fluoride and chlorine in our tap water. I would not even drink tap water these days... This is salt buildup in your soil. Use distilled water or (gulp) rain water and never allow any water to remain in your saucer. What fertilizer have you used? That could also add too many salts to your soil. This is purchased, potting soil from bags, yes? Do not make your own potting soil. I know what I am doing and I would NEVER make my own soil. You can also get a sterilized potting soil for cactus/succulents. Water and fertilizer for this guy...hey less is better!

  • It is city water, but here in Madrid is better than many bottled ones. Yet I have to add some drops of vinegar to correct the PH. I hadn't used any fertilizer. This was potting universal, soil from bags. It has been repotted now with soil special for cactus. – Martin May 7 '16 at 22:08
  • Does the soil have fertilizer elements included? Anything us humans try to grow a plant in new soil, new environment, NOT being part of an intimate and long term microenvironment will absolutely need fertilizer, water, ventilation, light ADDED to simulate its natural environment. Some soils have fertilizer (NPK plus micronutrients plus microbiologicals) incorporated but there is no way one can grow plants without SOME fertilizer. Fertilizer is NOT food for plants, plants make their own food. But those chemicals need to be accessible or poor health. If pH is not correct then those plants – stormy May 7 '16 at 22:18
  • ...won't make it. You are so lucky to have great tap water. In the states our water is pure crap. I wouldn't give it to my DOG. Browning tips, leaf margins is a great symptom of too much bad tap water, salts or fertilizer. – stormy May 7 '16 at 22:20

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