I had planted some roselle seeds in a seed tray with an old mix of cocopeat, perlite, vermiculite and compost. The seeds were soaked in water before planting for some time.
Now after eight days or so they are sprouting but two of them have one seed leaf rotten. Two of them couldn't break the seed coat. I had washed the seed trays with laundry detergent since I hadn't any sterilising agent available, but it was washed off with water thoroughly.
What could be the cause of this and how do I avoid it since I need to plant new ones?