3 Reasons to prune perennials

Some perennials, such as ‘May Night’ (‘Mainacht’) salvia and spike speedwell, have a large flush of flowers. When they’re done blooming, you could cut the entire plant back by a third and wait for a rebloom. Or you can get a second flush of flowers sooner when you selectively deadhead. This illustration shows how to remove the large center bloom to encourage the lateral buds to develop into flowers.

Even if flowers won’t rebloom, it’s a good practice to remove the spent flowers, or deadhead. Take a look at how the plant grows to know which method you should choose. Sometimes you’ll deadhead the entire flower stalk back to where it meets the base of the plant, as you would with hosta, iris and daylily, here. Other times shearing may work better. See how to do that next.

If there are too many flowers to individually snip, wait until a perennial is done blooming, and shear it all at once. Using hedge clippers, you can take a little off the top, or reduce the plant down to a few inches. This works especially well on mounded plants with lots of small flowers, such as ‘Moonbeam’ coreopsis and catmint, here. Be sure to leave a little foliage to help plants gather energy and regrow. Feed a balanced formula liquid fertilizer right away, and plants will often have a lighter rebloom in a few weeks.