Cutting Back and Pinching Perennials

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When you cut back a plant, you set back its bloom time by about 2-3 weeks.  Cutting back early in the season has a mild effect.  Cutting back in late June has a much stronger effect.

1.   Vacation cutting back – If you know that a plant will bloom when you will be away on vacation, you can manipulate its bloom time by cutting the entire plant back. An example is perennial hibiscus, which normally blooms in August.  If you cut this plant back by 1/3 to 1/2 in early July, you will create a shorter, branched plant that will not begin flowering until two to three weeks later than its normal bloom time.  i.e. the very end of August or the beginning of September.  Thus, when you return from vacation after Labor Day, your plant will just be starting its peak bloom time.

2.   Cutting back to achieve peak bloom for a party, wedding, or garden tour. Use the same concept described above to time blooming of perennials for special events. For example, if you are planning a September wedding in your garden, you can purposely cut back your late July and August bloomers hard in late June or early July.  Then, these will bloom in tandem with your regular September bloomers.

3.   Pinching or cutting back in stages to prolong the bloom time (double or triple it) and to hide the unsightly part of the plant after blooming. This is one of the most exciting advanced maintenance techniques a gardener can learn. The concept is to create a layered effect.  The back ½ of the plant is left alone to grow to its normal height and bloom at its normal time.  The front half of the plant is cut back by 1/3-1/2 in late May or June, at the latest the 4th of July.  The exact time of cutting back depends upon how quickly the plant grows and what time during the summer or fall a plant blooms.  Early bloomers such as Leucanthemum (Shasta daisies) are cut back in Southern Connecticut in late May or very early June as the growth is elongating but before the buds are setting.  Late bloomers such as Chelone lyonii ‘Hot Lips’ (Turtlehead) can have the front half of the plant cut back as late as early July.  The result is that the back of the plant blooms first at its normal time.  The front (pinched or cut back) half of the plant then begins to bloom 2-3 weeks later.  As the back half is finished, it can be deadheaded, it will be hidden by the blooming front half.  This doubles the bloom time and serves to detract the eye from the dying flowers and declining foliage of the back half of the plant.

 

    • This technique can be applied to a plant in three stages as well, which will triple your bloom time.
    • You can also take a large drift of one variety of perennials and cut back various sections at two week intervals, then manipulating and spreading out the bloom time for many more weeks wherever you desire.
    • If you discover that you have created jarring color combinations, this technique can be used to delay blooming of one of the two plants and thus prevent clashing colors!
    • This can be done with MANY perennials. Some of my favorites to use this technique on are: Asters, Solidago, Monarda, Leucanthemum, taller Veronicas, Eupatorium, Chelone, Hibiscus, Dendranthemas (perennial mums) Echinacea, Helenium, Heliopsis, Helianthus, Nepeta subsessilis, Physostegia, and taller Platycodons.

4.   Cutting back the front of a plant to staggered heights to clothe the plant with attractive foliage all the way to the ground. Some perennials, by the time they bloom, have “ugly legs”, i.e. they lose the lower leaves or the lower leaves become unsightly. Therefore, when you view them, the flowers are pretty but the foliage detracts. By cutting the front of a plant in stages, you can create a stepped or layered effect to the front foliage of the plant, hiding the ugly legs.  Try cutting the very front to 6”, the next level to 8-12”, the next level 15-20”, etc.

 

This information is based on the research done by Tracy DiSabato-Aust in her book

The Well Tended Perennial Garden.

This book is “our bible” and contains comprehensive lists and charts and a plant-by-plant explanation of what to do with perennials. It also discusses plants that should NOT be pinched. We refer to it constantly in our work. No gardener should be without it. It is one of the most popular books that we sell at Natureworks.

 

In an effort to provide horticultural information, these educational documents are written by Nancy DuBrule-Clemente and are the property of Natureworks Horticultural Services, LLC.  You are granted permission to print/photocopy this educational information free of charge as long as you clearly show that these are Natureworks documents.