FrillyLily ~ there is another herb that will substitute for the celery taste and can be eaten raw or used in cooking. That is Par-Cel. It resembles parsley but with the flavor of celery. Like celery, it is a biennual. It will last two seasons, then bolt, bloom and seed. The roots on this plant can be quite healthy. I have watched it wilt down when we have had a hard freeze and later in the day, it shakes off the frost and perks back up. If you are interested in trying some seed, I should have some to spare.
This is my first year growing lovage. Even as a small plant, it doesn't protest the cold so should do well for you. It has a definite celery flavor also.
I will take any extra celery that doesn't get eaten and chunk it and freeze it. Even when frozen, it works well when added to soups or other dishes where it will be cooked.