The best practice for letting your customers know you will be closed is to add a message to your store front page telling them the dates you will be closed, and blocking the dates that you're closed on the Delivery Calendar.
You can do this by navigating to Website > Design > Top Bar and typing up a message to your customers. This message will appear highlighted at the top of your site. For example, "The store will be closed for the dates of July 1st - July 4th. We looking forward to serving your floral needs on our return!"
Then go to Settings > Website Settings > Delivery Calendar and select these dates so that no new deliveries will be scheduled on the days you're out.