Answer: A general rule of thumb for deadheading perennials (cutting back the spent flowers) is to remove the flowers and the flower stalk or stem that they are attached to, back to the main stem of the plant. Penstemon, for instance, can have the flowering stem cut back to where the leaves are growing on the stem. Keep in mind that sometimes deadheading will result in two new flowering stems developing from leaf nodes on the main stem. Therefore, if you cut back to the leaves, you may very well get new stems that will produce smaller, but just as attractive flowers. With that in mind, you may chose to cut back a little lower on the stem so the remaining stem will be sturdy enough to support new growth.
Lily blooms can be cut off, along with the flowering stem, clear back to where the leaves emerge from the crown of the plant. Cut the stems back on columbines, as well as the others you've listed, to foliage level. You can lightly fertilize at the time you deadhead your perennials. Pinching and pruning plants in midsummer generally promotes new growth, so fertilizing at that time will help the plants respond to your requests. Hope this helps clarify things!
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