Tipping Late Blooming Perennials – Why & How

  • Difficulty Rating: Beginner
Tipping Late Blooming Perennials – Why & How

Usually, pruning out tip growth isn’t recommended.

Most plants tend to stay healthier and better looking if we prune out, say, an entire branch rather than just the tip end of it. There are a number of reasons for this, one being that the tip bud of a branch or shoot controls the growth of the parts below it. If that tip bud is removed, a plant’s means of controlling growth is also removed, and all sorts of things can go haywire. However, with a little understanding of plant growth, utilizing tip pruning (aka tipping or pinching) techniques can help us create bushier plants with abundant flowers. But, before you begin tipping everything in the garden willy-nilly, consider the following carefully.

Respect that tipping is a technique best used on the new growth of herbaceous perennial and annual plants. It is not a method recommended for woody plants; tipping can severely, negatively impact many woody plants, including trees and shrubs.

For perennials, be sure to consider when each blooms. Perennials that bloom in winter or early spring rarely can be tipped, re-grow and set flower buds before their ephemeral growing season ends. Late summer and early autumn bloomers, on the other hand, grow for the entire spring and summer before flowering; these are ideal candidates to tip. A few great candidates for pinching: hardy and annual fuchsia, tall garden phlox, tall sedums and asters or mums, which specifically set flower in response to shortening daylight hours.

Remember that by tipping out the taller growth on these plants, the plant’s growth may remain somewhat shorter than it would be if the plant were left uncut. However, when the buds below the cut point open, the plant will become bushier, with more potential points for flowers to form. This is great if you want to fill in a empty bed space or get the plants in a hanging basket extra bushy, but it can backfire if you need your perennial to grow tall in the middle or back of a flowerbed behind other plants.

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If you decide to try tipping your perennials, allow them to emerge from the soil and grow a few pair of leaves before you begin cutting them. When you do begin tipping them, pinch out the top few pairs of leaves. Make your cuts directly above a leaf, which is where new green growth will emerge from a bud tucked into the base of each leaf. When growth is supple in spring, cuts are easy to make with your fingernails. As it toughens up during a growing season, try using a pair of Micro-tip snips for accurate cuts. Buds that get damaged when you make your tipping cuts may die back or grow a deformed branch.

When deciding to tip back a perennial, you may choose to tip on shoot a few inches higher or lower than the pinching point on another shoot. This is called cutting to “alternating heights”. By doing this, your plant will grow to mixed heights and widths with flowers forming at different levels. Or, you may choose to tip the entire plant to uniform heights to create a rounder overall final form when the plant blooms.

As the season progresses, a late season bloomer can be pinched back multiple times. Each tip that is removed will be replaced by two or more shoots, which will emerge from the remaining buds below where you made your prior cuts. Then, once those new shoots have grown at least a couple of pairs of new leaves – usually within 7-14 days of the time you pinch -- they may be tipped as well. However, never try to re-tip a branch by cutting it at point below a prior pinch point. Only pinch newer growth that has emerged from other buds as a result of the original tipping.

Determining when to stop pinching back your perennials isn’t terribly tricky. You may simply get tired of doing it. Or, you may decide that the plant has filled in the space sufficiently, so additional pinching is no longer required. Or, the season may be on the wane, which means if you don’t stop pinching, the plant will never have time to set flower buds and bloom. Generally speaking, for late summer bloomers or fall bloomers, all pinching should end right around summer solstice – or if it’s easier to remember, make it the 4th of July. This is when the growing season plateaus and then begins to wind down slowly toward the fall Equinox and then winter. If pinching ends at about this time, late bloomers should still have sufficient time to put on a strong set of blooms to usher out the glory of summer.