For florist deliveries
The florist will place the flowers in front of the door or leave them with a neighbour. You can also place your delivery wishes in the "Comments for the florist" field.
For courier deliveries
The courier will try to deliver the flowers to the neighbours when nobody is home. You can also check if there is an option to change the delivery on the tracking page of the courier service. This page can be found in the email you received from the courier service.