Hi Nancy,
I recommend "The Well-Tended Perennial Garden" by Tracy DiSabato-Aust for detailed instructions on how to care for your perennials.

Here's some of what Tracy has to say about rose campion (Lychnis coronaria):

"Regular deadheaing, every week or so through July and August, can prolong bloom by several weeks or more. Deadheading each small individual seedhead to a new lateral flower or bud is a tedious job. Snipping with sharp pruning scissors and just letting the deadheads drop to the ground appears to be the most efficient method.
Deadheading before seed sets can prevent prolific reseeding."
"Cutting the old flowering stems down to the fuzzy basal leaves before seed set, and thus preventing seeding, may prolong the life of the existing plant in the garden. These normally biennial plants may act more perennial in nature if treated this way."

SO, Nancy, as the blossoms begin to fade, simply take your pruning shears or clippers and snip off the flowerhead. As Tracy says, you have to keep doing this every week or so. Hope that answers "how, when and where"!

PattiOh

thank you soooooooo much!