I have just experienced some very similar symptoms
Young seedlings (6 weeks)
- outdoor summer
- browning leaf edges
- some brown spots in the middle of a few leaves ... some becoming holes
- some necrotic leaves low down
But the odd thing was that all my new growth is a healthy dark green
At first it was looking like a nutrient excess or deficiency ... but my end conclusion is in agreement with both
hotrodharley and
ClaytonNewbilFontaine
I had just topped my seedlings a few days before, when we had some very windy hot days all in a row.
44 km/h | 28 mph
36°C | 96°F
So my logic was:
- the leaves of the young plants were losing water faster than they could replace
= strong wind
= high heat
- the effect of the topping was 'directing the available nutrients' to the new top growth
= due to the wind and heat
... the water supply from roots to leaves was sub-optimal
= the nutrient supply was limited
... by the lack of water transport
= and nutrients were being 'stolen' from the lower leaves
..,. to supply the new growth
Looks like a potassium deficiency existed but didn’t progress. Saying this because spotting is on the edges only where calcium deficiency would probably be more widespread.
It's right around midway up the plant. I was getting some necrotic leaves down below, but I really think it's just wind damage. I'm going to feed them again tonight so hopefully it'll clear up.