It depends upon the plant, but generally speaking it is a good idea to remove the spent flowers. That is what is called 'dead heading'...I'll bet that you've heard that term. Some plants require deadheading in order to continue production of flowers, others aren't so particular.

Dead heading allows your plant to put more energy into making more blooms instead of making seeds. Plants aren't crazy about having to tend to both tasks at the same time.

Just so you know, you can find even more information about annual and perennial plants in the forums with those titles. Of course, we're happy to answer your question here.

Do you know what kind of flowers you have?

I didn't think to look for annuals or perennials. Just searched for flowers.

I have a bunch of flowers. Here they are.

Dianthus (Telstar Picotee)
Red Marietta (Marigold)
Castle Mix (Celosia)
Hawaii Blue (Ageratum)
Victoria Blue (Salvia Farinacea)
Vista Red (Salvia)
Orange Boy (Marigold)
Sunstorm White/Eye (Vinca)
Portulaca (Margarita Rosita)
Sonata Pink Blush (Cosmos)

Thoughts? Thanks.

The only plant that wouldn't benefit from deadheading is the portulaca. Even that one will like a hair cut mid-season, when grown in containers.

Thanks for the thoughts. I have trimmed all but the Portulaca and it looks a little cleaner now.