I planted rucola seeds on 29 September, and they germinated very quickly. Some of them are now growing a small third leaf but for a vegetable that is supposed to be a "fast grower", it seems to be growing very slowly. The attached photo was taken 2 weeks after sowing. Should I add fertilizer at any stage? I bought Miracle Grow All Purpose Plant Food. And if so, how should I adminster it? Thank you.