Evergreen content is always relevant—it's not time or date bound.
In the context of ConvertKit, our Sequences are designed to be evergreen. That means that anyone can sign up for your Sequence at any time, and two different Subscribers would receive your emails in the same order, but on different days.
When you are getting ready to release a product, you can decide if you want it to be evergreen or not. If it's evergreen, anyone can purchase at anytime. If not, your cart would close, and there would be a "last day" for your Subscribers to purchase. Neat, huh?
Advantages To Evergreen
Some advantages to creating evergreen content is that it's easy to manage. You don't have to worry about the logistics of time-sensitive promotions or cart-closings! That's a relief.
Additionally, while your Subscribers might not be ready to purchase a product, for example, during your first (or even fifth!) pitch, chances are, down the road they will be! Using evergreen content to continue soft and hard pitching your products to your audience increases the percentage who end up buying from you.