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I planted a Silver Tree (Leucadendron argenteum) a few months ago in a spot where it gets several hours of sunlight. Recently, its lower leaves started turning yellow; see photo:

Leucadendron argenteum

Is this a cause for concern? If so, what's likely the problem and how do I remedy it?

No, I haven't fertilized it; and I know that the plant doesn't like phosphorus.

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  • Have you been watering it and if you have, how often and how much?
    – Bamboo
    Apr 17, 2022 at 18:45
  • Yes, I’ve been watering it, though not explicitly lately since it’s been raining. Last week, it was looking a little droopy, so I watered it and it perked back up. Apr 17, 2022 at 19:32

2 Answers 2

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I think the problem is down to lack of water; although these trees like free draining soils which are not constantly wet, it is still a tree, and all trees need watering during the first 1-2 years after planting, until they've established a good root system for themselves. Water it with a few gallons at least once a week, and if it's hot and dry, 2 or 3 times a week - if its raining but the rain isn't torrential, you should still water it once a week. If you have anything that passes for autumn/winter, when temperatures are much cooler or cold, it won't need watering then, but for the rest of the time, it will till it's been in situ for a year to 18 months.

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Firstly, you should know that yellowing of large number of leaves indicate a nutrient problem (If you see browning allong with yellowing it indicated rots due to overwatering). Your plant seems healthy, just that it shows neon leaves which confirms that it's not a rot but rather a deficiency.

Now, there are two types of nutrient deficiencies:

1.) Immovable nutrient deficiencies: This includes deficiencies caused due to heavy metals (i.e. Iron, Zinc, Molybdenum, etc. You should address this sort of deficiencies with foliar spraying (spraying directly on leaves for absorption), since, such metals cannot move much into plant tissues.

2.) Mobile nutrient deficiencies: This category includes lighter plant nutrients which can easily move through cell walls of plant tissues.(i.e. Nitrogen, Potassium, Phosphorus, Magnesium, etc.). What happens with mobile nutrients is: When a plant faces a scarcity of such, it automatically diverts the remainder of nutrients to "newer" growth and goes into growth spurt mode for survival.

Yellowing of leaves is a symptom of Iron, Magnesium or Nitrogen Deficiency. If it was Iron, newer growth would've been yellowed (since it's immobile), thus we can eliminate the possibility and it can't be iron deficiency. It surely is a Nitrogen or Magnesium deficiency and owing to the fact that there are many succulents growing nearby, they leech out all the nutrients and thus your Lucadendron competes for nutrients with them. Flush high Nitrogen Fertilizers and Epsom salt to that area sooner.

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