My alocasia was super happy indoors in the winter. I took it out starting from April. It is in full sun for 3 hours a day and then shade or semi shade. Can't see any pests. I fertilise every 3 weeks and I gave iron too. However leaves turn yellow, crispy and then holes develop. And it's not even the oldest leaf. Could it be the sun? Temperatures here have reached a maximum of 83 F so far.

What size of a pot is it in? What formula fertilizer are you using? Perhaps it is not strong enough for it? Is it a macrorrhizos? They need lots of fertilizer!
But could be water too..how do you know when to water? When the heat is on plants start growing faster and need more water and more fertilizer too.

skylark said: What size of a pot is it in? What formula fertilizer are you using? Perhaps it is not strong enough for it? Is it a macrorrhizos? They need lots of fertilizer!
But could be water too..how do you know when to water? When the heat is on plants start growing faster and need more water and more fertilizer too.

Tbh I think it is sunburn. I repotted recently. Now it has a big new leaf. I will wait and see. If that too dries I'll move the plant to shade.

I water every other day and fertilize every three weeks. Do you think it's enough?
If temperature reaches 100F or above I'll certainly keep it in shade all day and water daily. So far temperatures don't exceed 87F.

Sunburn has reddish brownish cast , not like these yellow edges.
What is your fertilizer formula and how much do you give ?

skylark said: Sunburn has reddish brownish cast , not like these yellow edges.
What is your fertilizer formula and how much do you give ?

It's a 20-20-20 general purpose fertilizer. I fertilize every 3 weeks.

To me it looks like physical damage, maybe from the repot.
How big IS the pot? Watering every other day seems a bit frequent. If it dries out that fast it probably needs an even bigger pot.
Don't move it back and forth depending on temperature, Sunburn is dependent on light intensity not air temperature.
How much fertilizer do you use when you fertilize and how much does the package say to use? If the package says use 1 tablespoon and you use 1/2 a tablespoon, you're not getting the same response. On the other hand if you use 1 1/2 tablespoons you could be burning it.

I think I use as much fertilizer as written in the instructions although it's difficult to be sure when we are talking about 1/4 of a teaspoon..
It's definitely not due to repotting as it has been happening since before that. Same thing happened last year when I did not repot and the pot was actually too big.

Here's a photo of the current pot and the old one for comparison.

Is this a A. macrorrhizos ?

You can not make this assumption. 3 hours of sun, On June 30th, is the same in Miami, Jacksonville, Charleston, Newport News, New York or Maine.
2 big differences:
Angle of the suns rays. The further North you go on that one date, the higher the sun is in the sky. For example, on June 20th in Miami the sun is roughly at 88.5 degrees, almost directly overhead. The suns rays are striking the plant after passing directly through the atmosphere.
At Newport News, I have not looked this up but for the purpose of this discussion, let us say it is at 60 degrees. The sunlight on an angle comes through more of Earths atmosphere and all of its goodies, ie. Particulate matter or pollution if you will. So the suns rays are less intense in Newport News versus Miami because of angle in the sky AND angle in relation to atmosphere.
In NYC, the sun on June 20th, rises to about 42 degrees above horizontal making it lower in the sky and less intense. Less intense as it passes through more atmospheric pollution.
Look what is directly west of NYC, states with big urban populations with lots of pollution being spewed. This lessens sun intensity.
What is way west of Miami? The Gulf of Mexico. Not a lot of big cities floating around in the gulf. Less particulate matter, less pollution leading to more intense sunlight.

So to think that putting out a plant in NYC sun for three, mid day hours, is the same as if you put it out in Miami, is not remotely true.
I had the pleasure of spending 9 years in SW Florida. The Summer sun was just so intense. Putting plants outside in that kind of sun, AND heat, it was like you were pan frying them.
When plants become stressed by too much light, the last thing they need is fertilizer. I fertilize my 200 orchids, growing indoors, about 6 times a year @ half strength.
Other plants growing in potting soil do not require a lot of food either in my opinion. Where are they going, or growing, that they need a lot more food?
I feel that fertilizer has become an excuse for poor growing habits. Fertilizer to me is meant to support good plant growth, it does not create good growth. Way too many people use it like a plant tonic or like a medicine.

Just my 3 cents worth.

OP is in a very dry and hot climate near Athens, Greece. And if I remember his previous posts this is A. macrorrhizos.
Which can be grown in full sun in Texas..
So he is not misguided to give it a few hours of sun . It is a hungry feeder and in habitat grows near streams and can even stand in water. When grown in ground it can push out a leaf a week and get to 12 feet :). It loves hot and steamy with daily drenches ..
with all the heat (97F in Athens now and will only get hotter ;)) and 25% relative humidity during the day..it can and probably should be watered in a pot daily..
and due to frequency of watering should be fertilized often, probably more often then he does now.
So..I suggest light watering in the morning to wet the medium following with 2nd watering with fertilizer diluted to half strength weekly. The medium should be porous enough to drain quite fast. It should be a fast grower too. And leaf evaporation will be high in such dry and hot conditions, so basically you can't water it enough..
In all fairness you can't compare it to growing orchids :).
@wandering_ant, I suggest that you go to your profile and in location add 'Athens, Greece' so it shows up with your posts: it is necessary for giving appropriate growing advice.

skylark said: OP is in a very dry and hot climate near Athens, Greece. And if I remember his previous posts this is A. macrorrhizos.
Which can be grown in full sun in Texas..
So he is not misguided to give it a few hours of sun . It is a hungry feeder and in habitat grows near streams and can even stand in water. When grown in ground it can push out a leaf a week and get to 12 feet :). It loves hot and steamy with daily drenches ..
with all the heat (97F in Athens now and will only get hotter ;)) and 25% relative humidity during the day..it can and probably should be watered in a pot daily..
and due to frequency of watering should be fertilized often, probably more often then he does now.
So..I suggest light watering in the morning to wet the medium following with 2nd watering with fertilizer diluted to half strength weekly. The medium should be porous enough to drain quite fast. It should be a fast grower too. And leaf evaporation will be high in such dry and hot conditions, so basically you can't water it enough..
In all fairness you can't compare it to growing orchids :).
@wandering_ant, I suggest that you go to your profile and in location add 'Athens, Greece' so it shows up with your posts: it is necessary for giving appropriate growing advice.

Thank you, I've added my location already.

Actually and surprisingly, so far our summer has been relatively humid. Humidity is about 50-60% on most days. Not bad at all for our standards. Temperatures in my yard stay mild, not exceeding 86F. So for now I water every other day. Later in the summer I am sure it will get drier and hotter so I'll water daily.

So far the two newest leaves seem OK, so I'll wait and see. It grows a new leaf every 10 days or so.

I am thinking that perhaps the new pot is already a bit too small. Is it a problem if I repot twice in two months? Last time was 12 May.

it's not a problem if you uppot without disturbing the roots: try to pull it out by gently rolling on the side to tease the root-ball out. and then just put it in a larger pot with soil intact. Fill the sides (and at the bottom too). water in well. It is ok to do so with very fast growing plants when the soil was changed recently.
post a pic of root-ball if you can: with this plants you should have a lot of roots there.

I agree .... looks like physical damage to me too

wind will cause that in seconds .... pets or kids around might also cause it

deepsouth said: I agree .... looks like physical damage to me too

wind will cause that in seconds .... pets or kids around might also cause it

That would make sense because I live in a very windy place.

skylark said: it's not a problem if you uppot without disturbing the roots: try to pull it out by gently rolling on the side to tease the root-ball out. and then just put it in a larger pot with soil intact. Fill the sides (and at the bottom too). water in well. It is ok to do so with very fast growing plants when the soil was changed recently.
post a pic of root-ball if you can: with this plants you should have a lot of roots there.

You were right. The pot was full of roots. I'm amazed at how fast they grew. All looked bright white and healthy. I had to untangle them. I didn't take a photo cos I did it at night.
The new pot is quite larger but I bet I'll have to repot again in September! I used a mix of regular compost, seramis and pine bark.

Great! Come back and post pics in the fall when it grows.
How is yr plumeria?

skylark said: Great! Come back and post pics in the fall when it grows.
How is yr plumeria?

My plumerias are doing well. Got two now. All plants are doing well atm. They love June weather.

Alocasia is growing more slowly now, it takes days for the new leaf to open. I guess it happens

It is growing more roots now, it is busy 😁!

When you transplant the next time, don't disturb the roots. Just pop it out of one pot and put it in the bigger pot. It won't slow down if the roots aren't disturbed. They grow a whole new root system each year so they don't actually get "root-bound".