Help! Seedlings germinated, then died - see photo
What do you think could have caused these tomato seedlings to germinate, then die? I want to start a lot more seedlings, but I don't want to make the same mistakes again!! I have successfully started tomato (with 100% germination) & other seeds in the past, and they did well.
I started 40 tomato seeds in 40 3/4" soil blocks 7 days ago. The seeds were not covered with soil. Some sprouted in 3-4 days.
17 germinated, they arched up from the soil, but the cotyledons did not emerge, then they died.
9 germinated, cotyledons stood up, but the cotyledons could not shed their seed casings to get light, and are now nearly dead.
7 germinated, are still alive, but growing VERY SLOWLY. Only one looks healthy.
7 did not germinate.
Soil Temp during germination: 79Ã¯Â¿Â½F (26Ã¯Â¿Â½C)
Soil Temp after germination: 70Ã¯Â¿Â½F (21Ã¯Â¿Â½C)
The seeds are various varieties, 1 to 4 years old.
During germination they were wrapped in a plastic bag with a small airhole. It was removed when they germinated.
Once germinated, they sit in a full sun, south facing window (but, I live at latitude 51Ã¯Â¿Â½N). This is a dry climate.
Soil Blend: 60% coconut coir, 39% worm castings; 0.3% kelp meal, of 0.3% azomite, 1% zeolite, 0.05% glacier rock dust, 0.15% all purpose organic fertilizer (Soyabean meal, Kelp meal, Alfalfa meal, Sunflower Hull Ash) [Yes, I know they don't add up to exactly 100 :) As far as I understand, these organic fertilizers don't burn roots like chemical ones do, and there is a very small quantity of them.
This does not look like damping off. They did not keel over, and there is no week spot on the stems at the soil level.
I am thinking that I probably over-watered them, and they died from lack of oxygen. Would you agree? Is there anything else that may have contributed to their poor health? I would appreciate any suggestion you might have :)
Also, should I be gently removing seed casings from the cotyledons? When I try, I usually seem to end up ripping the cotyledons!
Thank you very much!