Lots of hydroponic solution recipes have no ammonium, just nitrates and they work just fine. The relative costs (and legal availability) of Ammonium Nitrate compared to Calcium Nitrate may also affect their usage.
I've had the same Haworthia for over 10 years now. During that time I have:
Put it into too large a pot, which led to root rot
Dumped the rotted plant out onto a garden bed in full sun
And it did not die. In fact, should you ever overwater the plant until it gets root rot, I recommend just tossing the rosettes someplace in your ...
I think you went a bit too extreme to the other side ;) dry tips often indicate either sun damage or underwatering. Move it to a shadier place and water it.
ps. a sign of overwatering would be yellowish leaves, which I don't think you've experienced.
I take it you did not read the label on the Roundup Path Weedkiller, which states quite clearly 'do not use on lawns'...so that's the first lesson, read labels and instructions! Unfortunately, now that you have used it, you will need to wait at least 4 weeks to make repairs to the lawn where the bare patches are. And a word about glyphosate (particularly ...
I actually read the 1 star reviews on the soil I purchased and looks like everyone had mould problems (some even bugs in their new bags)... looks like it’s best to re-pot with a different brand and as someone suggested, water less frequently.
Potatoes requires watering, but not too much watering.
I think you should reduce watering. If you have fungus, probably you water too much. I never have problem with irregular (and seldom) watering of potatoes, so I'm surprised to your comment.
As alternatives: a watering system, where you water soil and not the surface helps. Or a top layer of sand helps.
It certainly seems to be a Foxtail palm; whether it will cope with the intense and constant sunlight is hard to predict. They cope very well with sun, and with salt laden breezes, but they do like humidity, so the lack of humidity might be an issue. It will certainly need watering at least once a day.
I have reservations about the two in one pot being a ...
Manganese deficiency – If new fronds are yellow or display yellow splotches, the tree may be lacking manganese. This often occurs when the tree is planted in manganese-poor soil, which is common in tropical climates. This deficiency is easily treated by applying manganese sulfate (not magnesium sulfate, which is completely different).
Read more at Gardening ...
I have mine with the same spots. My ZZ looks pretty healthy. Once a month I take all the dust from on top the leaves. I water occasionally. But I check the soil 3 X a week. I love mine. So, I really recommend to you, put set in your calendar, once a week to check your ZZ. You will never forget to water. Also, I talk with mine, I kiss some leaves, in my home ...