Buds will open up fastest, bloom best, and last longest if you keep your container of forsythia stems in a cooler spot that gets a bit of sun. At the garden centre, we keep ours close to the door of the store where the floor stays cool and put them out on the front step on milder days.
PS. Try these stems in flower arrangements, centrepieces, even in early spring planters in a sheltered spot at your front door. Take a photo of your creative masterpiece and share it with us!