Something tried to nibble on Plant B, however there are no signs of pests and no further damage anywhere else (I have 6 other plants in the garden too). Plant A has already begun to develop stipules on its first set of true leaves too!
Had their first feed on day 14 (2ml Fish Mix + 0.1ml Mono-silicic Acid), and were fed again on day 16 (2ml Fish Mix, 2ml Bio-Grow, 2ml Bio-Bloom, 0.1ml Mono-Silicic Acid).
