I would check if chives would be a perennial in you zone. I'm in zone 5 and they come up every year. If they do then they can be very large plants. I would not plant 9 in one square. Green onions will take that spacing but perennial chives would crowd too much. I would also suggest always having lettuce at the edge of a bed by swapping your interior lettuce with the celery and carrots. Especially if it is leaf lettuce you will want easiest access to pick off as you need. While your carrots and celery just need time to mature with little upkeep. Good luck! This looks great.