I have a small vase in each guest room on the window sill, a shot glass with a few flowers on each breakfast table and a large display on the desk in the hall.
I buy them in the supermarket some of the year, after a while you get to know what'll last and what doesn't.
I also grow them in the garden and on the veggy allotment specifically for the house, gladioli, statice, dahlias, sweet peas and sunflowers are all great performers to grow and will supply from mid summer through to first frost. Gladioli green star in a vase with blue statice looks amazing, sweet peas fills the guest room with scent. Daffs and tulips are from early April through to mid May.
I probably buy 50% of the year and the rest are from the garden.
Never thought about the cost, I think it's one of those little touches that elevates your business so I've never worked it out, plus I enjoy growing them.
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