These “Earth Vows” come from a favorite Handfasting book, and would be especially suited to an outdoor ceremony. Based on what you said about the venue, I thought these might offer even just a few lines you’d like, but here’s the whole set:
By seeds of all beginnings, I make this oath.
By roots of all depths, I swear to love you with all my might.
By stem and trunk that reach for the sky, I swear to respect your soaring spirit.
By bud that grows, I swear never to crush your dreams.
By leaf that kisses the sun and rain, I swear to share my joys and sorrows with you.
By flower that opens to the dawn, I swear that I do trust you.
By fruit that gives forth sweetness, I swear to nourish and support you.
By seed within the fruit that grows the tree anew,
I swear to begin anew with you, again and again,
As many times as the gods will decree.
By life and death, by Lord and Lady, by hand and eye, by heart and spirit,
This I do swear to you here before the Fates
And mark my soul forever with your touch.
As all green things grow, so shall our love,
And its memory be carried forever beneath the feet
Of a thousand generations to come.
— Congratulations, and Be Well!