HELP! Yellowing leaves + black spots: outside grow, plenty sun+water. fish fert every 2wks

[sofired]

Can't see any bugs. The leaves on a couple of the plants have been light green/yellow for weeks. Only one plant (put in ground much later than earlier ones) has nice deep green leaves. Now, I'm starting to see black spots on some leaves (of the plants with the light green/yellowish leaves...)

[Canuck147]

Calcium magnesium deficiency