Pepper seedlings not thriving
Hoping you guys can help. I started my pepper seedlings a month ago and they are just now putting out their first true set of leaves. Is this a normal growth rate??
Some more info, if it's helpful:
I started many varieties of peppers (sweet and hot) about Feb. 20th. I started them indoors, using Speedling trays and standard plastic seed trays, using shop lights and bulbs marked "for plants and aquariums". I am using Burpee's organic soilless mix, with coir as main ingredient. I have them in a shelving unit with onions and lettuces, so I can't keep the temperature as high as peppers would probably like, but have aimed for an even middle of the road compromise of 68-72 degrees. They were getting 24 hours of light, but I realized my mistake early on (after about a week) and started givin them 12-16 hours of light.
The seeds germinated well, but don't seem to have made much progress in the month they've been growing. They are just now putting out their first set of true leaves. I do (now) know I had been overwatering them, as a lot have turned purple/yellow. I have since corrected this.
I gave a very diluted dose of fish emulsion in their water about a week ago, which made the few I tested it on shrivel up. (Still too concentrated??) A still-more diluted solution was given to them as a foliar spray a few days ago and seems to have worked better.
The seedlings just don't seem to be thriving, some barely growing at all and others ouright dying. Would a seedling heat mat help matters at all? I'm hesitant to drop a lot of money ($22 each + $38 thermostat for each tray???), if it won't help.
Any advice would be greatly appreciated.