Potassium deficiency? Help please!

[BlackPebble]

After a crazy amount of googling I feel like this might be potassium deficiency? This is my indoor coconut palm tree, just over 1 year old. I live in the UK, we don't see sun all that much, so I bought it an LED grow light recently, because I though these spots were due to not enough sunlight. I'm feeding it with a 2.1 : 0.9 : 3.6 fertilizer, although not very often to be honest. 
(Ignore the curly leaves, that's normal because I'm growing it as a bonsai)

 

[Tomas]

I agree with the potassium deficiency except in the last picture, that I guess could be low humidity, too much salts ...

To correct potassiumd deficiency, you need to supply also Magnesium, it is possible to add it with Epsom salt

[Merlyn]

Spotting is typically potassium deficiency, but it looks like the end of the new leaves (last photo) are green near the base and transition to yellow near the end of the leaf.  If that's true (and not just a photo oddity) that would be a Manganese deficiency.  Make sure your fertilizer has the "minor elements" like Manganese, Iron, Boron, etc.  Here's my notes on fertilizer deficiencies, hopefully this helps!

• Nitrogen - Older fronds turn light green uniformly, new fronds remain dark green until deficiency is really severe
• Potassium - Older fronds get translucent yellow/orange or dead spots on leaves, especially at the tips. Caryota and Arenga get random splotched dead spots in leaves. Sometimes tips are curled or frizzled. Always starts at tips of oldest leaves, moving inwards
• Magnesium -Yellow ends on oldest leaves first, transitions to solid green at the base of each leaf. Never causes leaf tip necrosis
• Iron - Many times caused by overly mucky soil and root rot. Starts with new spear leaves with yellow-green or even white, possibly with spots of green.
• Manganese - Lengthwise necrotic streaks in NEW leaves with dead and curled leaf tips. Similar to bands showing Magnesium deficiency. Mn is NOT mobile, so it can't be stolen from old leaves.
• Boron - Bent or necrotic or distorted leaf tips, distorted or bent spear, bands of dead spots on new fans, spears that won't fully open
• Water - Underwatering brown at the edges first, later followed by yellowing of the whole leaf. Overwatering can be drooping fronds turning yellowish and losing color
• Dolomitic Lime or Azomite - Magnesium Carbonate – reduces acidity/raises pH – slower release and adds Magnesium, helps avoid Potassium deficiencies in Cuban Copernicias. 5Lb per palm on full-size Copernicias and a bit less on Kentiopsis Oliviformis
• Garden Lime - Calcium Carbonate – fast release but works well. 5Lb per palm on full-size Copernicias and a bit less on Kentiopsis Oliviformis
• Sunburn - Orange/Red/Brown streaks on surfaces facing the point of hottest sun, typically the worst case is around 1-4pm. Sun tolerant species will adapt and grow out of it. Shade loving species may never adapt.

[Than]

18 hours ago, Merlyn said:

Spotting is typically potassium deficiency, but it looks like the end of the new leaves (last photo) are green near the base and transition to yellow near the end of the leaf.  If that's true (and not just a photo oddity) that would be a Manganese deficiency.  Make sure your fertilizer has the "minor elements" like Manganese, Iron, Boron, etc.  Here's my notes on fertilizer deficiencies, hopefully this helps!

• Nitrogen - Older fronds turn light green uniformly, new fronds remain dark green until deficiency is really severe
• Potassium - Older fronds get translucent yellow/orange or dead spots on leaves, especially at the tips. Caryota and Arenga get random splotched dead spots in leaves. Sometimes tips are curled or frizzled. Always starts at tips of oldest leaves, moving inwards
• Magnesium -Yellow ends on oldest leaves first, transitions to solid green at the base of each leaf. Never causes leaf tip necrosis
• Iron - Many times caused by overly mucky soil and root rot. Starts with new spear leaves with yellow-green or even white, possibly with spots of green.
• Manganese - Lengthwise necrotic streaks in NEW leaves with dead and curled leaf tips. Similar to bands showing Magnesium deficiency. Mn is NOT mobile, so it can't be stolen from old leaves.
• Boron - Bent or necrotic or distorted leaf tips, distorted or bent spear, bands of dead spots on new fans, spears that won't fully open
• Water - Underwatering brown at the edges first, later followed by yellowing of the whole leaf. Overwatering can be drooping fronds turning yellowish and losing color
• Dolomitic Lime or Azomite - Magnesium Carbonate – reduces acidity/raises pH – slower release and adds Magnesium, helps avoid Potassium deficiencies in Cuban Copernicias. 5Lb per palm on full-size Copernicias and a bit less on Kentiopsis Oliviformis
• Garden Lime - Calcium Carbonate – fast release but works well. 5Lb per palm on full-size Copernicias and a bit less on Kentiopsis Oliviformis
• Sunburn - Orange/Red/Brown streaks on surfaces facing the point of hottest sun, typically the worst case is around 1-4pm. Sun tolerant species will adapt and grow out of it. Shade loving species may never adapt.

So useful, thanks a lot. Some of my hibiscus leaves have the same symptoms like Manganese deficiency. They start yellowing from the tip. I am attaching a photo. However they are not new leaves. Seems to be affecting random leaves. What could it be? 

All leaves btw seem to be pale, light green this year.

 

Edited June 14, 2023 by ego

[Merlyn]

@egoas I understand it:

• Magnesium is "mobile" from leaf to leaf.  In palms the first visible sign of Magnesium deficiencies is yellowing of the tips of leaves on the oldest leaves.  That's easy to tell on a palm, because oldest leaves are the lowest.  I don't know if that's the same on deciduous plants.  Some of them drop leaves at random, so it's hard to say which leaf is the "oldest."
• Manganese is "not mobile" from leaf to leaf.  So the visible sign of a Magnesium deficiency is yellowing or browning or "frizzle top" of the newest leaves.  This frequently happens as the frond finishes growing.  So it might grow out looking sorta normal and a pale green.  Then as the leaflets transition from light green to dark green the ends can be yellowed or even necrotic.  As it gets worse, the new fronds grow out yellowed and distorted and necrotic. 

If I had to guess, I'd think your hibiscus needs Magnesium.  I use a Rite Green brand Magnesium Sulfate, bought in a giant bag from Home Depot.

[Than]

6 minutes ago, Merlyn said:

@egoas I understand it:

• Magnesium is "mobile" from leaf to leaf.  In palms the first visible sign of Magnesium deficiencies is yellowing of the tips of leaves on the oldest leaves.  That's easy to tell on a palm, because oldest leaves are the lowest.  I don't know if that's the same on deciduous plants.  Some of them drop leaves at random, so it's hard to say which leaf is the "oldest."
• Manganese is "not mobile" from leaf to leaf.  So the visible sign of a Magnesium deficiency is yellowing or browning or "frizzle top" of the newest leaves.  This frequently happens as the frond finishes growing.  So it might grow out looking sorta normal and a pale green.  Then as the leaflets transition from light green to dark green the ends can be yellowed or even necrotic.  As it gets worse, the new fronds grow out yellowed and distorted and necrotic. 

If I had to guess, I'd think your hibiscus needs Magnesium.  I use a Rite Green brand Magnesium Sulfate, bought in a giant bag from Home Depot.

I gave it Epsom salts a few days back but no difference. 

[Merlyn]

1 hour ago, ego said:

I gave it Epsom salts a few days back but no difference. 

Fertilizers are generally to prevent future deficiency symptoms or a progression of symptoms.  Once a leaf has gone yellow or pale or brown it's probably not going to turn back green.  The only exception is pale leaves due to nitrogen or iron deficiency.  In those cases a pale leaf might change to a deeper green.  But if it's yellow...it's that way permanently.

[Than]

1 hour ago, Merlyn said:

Fertilizers are generally to prevent future deficiency symptoms or a progression of symptoms.  Once a leaf has gone yellow or pale or brown it's probably not going to turn back green.  The only exception is pale leaves due to nitrogen or iron deficiency.  In those cases a pale leaf might change to a deeper green.  But if it's yellow...it's that way permanently.

True but what I meant is that the problem persists; more leaves turn yellow. Anyway, I'll see how it goes.

[Johnny Palmseed]

A few days is probably not enough time for any change.

[Merlyn]

8 minutes ago, ego said:

True but what I meant is that the problem persists; more leaves turn yellow. Anyway, I'll see how it goes.

Fertilizers act more on the scale of weeks and months, very rarely days.  Extra Magnesium might not help a lot, and it may be something entirely else that's causing the Hibiscus leaves to die off sooner than normal.  Root rot and all kinds of other problems can cause nutrient uptake issues, which is why sometimes a foliar spray is useful.

[Than]

1 hour ago, Merlyn said:

Fertilizers act more on the scale of weeks and months, very rarely days.  Extra Magnesium might not help a lot, and it may be something entirely else that's causing the Hibiscus leaves to die off sooner than normal.  Root rot and all kinds of other problems can cause nutrient uptake issues, which is why sometimes a foliar spray is useful.

True, it could be the coco coir I use as medium. Perhaps salts or smth else. I'll have to check the salt content of the medium somehow I guess.

[Than]

2 hours ago, Johnny Palmseed said:

A few days is probably not enough time for any change.

However I can see the difference with other plants that were pale green. After just 3-4 days of applying iron or manure, the colour of their leaves changed dramatically. My acalypha hispida for instance. Also my small hibiscus. It's only the older hibiscus that still looks unhappy. Perhaps it's the soil

[Johnny Palmseed]

It could be the soil. It could also be the age of the plant. I would think that a smaller or younger plant would react quicker than an older or larger one.