Every week or two, as I am deadheading the spent blooms on my lantana, I think about this distinction. What am I talking about?
Think about annuals, for a moment. A true annual’s function is to set seed and die. Not all plants that we grow as “summer flowers” are annuals, of course. Many of the “annuals” that we grow up here in the frozen north, as I like to call my climate, would be perennials if I lived somewhere further south or west.
So an annual, like a marigold, for example, or my lantana (which is technically a perennial in warmer climates), or impatiens or begonias or lots of the flowers we grow in the summer, either need to be deadheaded (have the spent blooms removed), or they are “self-cleaning,” a handy little feature which means that the flowers fall off themselves.
Now, in the case of something like impatiens, depending on species, sometimes they still form a seed head. That gives rise to one of their common names “Touch Me Not,” because if you’ve ever touched a ripe impatiens seed head, you know that it can explode with surprising force and send those seeds flying!
Perhaps the best example is something like basil. You’ve always heard that you don’t want your basil to flower. Why is that? Well, basil is a true annual and once it flowers it begins to decline.
The same is true for cilantro, another annual. You don’t want that flowering (unless you’re growing it for the coriander seed it makes–or as a pollinator plant!)
As for my lantana, every week–or two, if I am lazy–I just cut off the spent flower heads–and perish the thought, any seeds that they’re forming. I want all the energy to go back into the plant to produce as many flowers for bees and butterflies as possible!