Primetime Newspapers
By Calvin Finch, PhD, SAWS Conservation Director, and Horticulturist
Week of December 20, 2004

Reasons to Delay Retiring the Mower and Cutting Freeze Damage

           

            Do not be too quick to retire your lawn mower for the season or too quick to cut back the freeze killed foliage. 

            The mower can be useful in dealing with the leaves that have fallen on the lawn and mowing the lawn several times per month during the winter will help keep the winter weeds under control. 

            It does not make sense to rake up the leaves and send them off with the garbage truck to the landfill.  The leaves are valuable organic material and should be recycled.  The easiest way to recycle the leaves is to just run the lawn mower over them where they lay on the lawn.  Chopped up into small pieces, they will decompose quickly and return valuable nutrients and organic material to the landscape.

            If your yard is blessed with shade or burdened with poor soil, winter weeds can be a problem.  Applying a pre-emergent herbicide in September next year may help, but for this year mowing may be the best strategy.  Mow frequently enough to keep the lawn neat and, absolutely, mow enough to prevent the weeds from going to seed.  When the seed heads begin to form, rev up the mower.  It will reduce the seed available for next year, a desirable thing.

            After two freezes this autumn already, one of the most frequent questions I receive is, “when should we cut off the freeze damaged foliage?”.  The issue is debated by horticulturists.  The best answer may be different for each landscape and gardener, or even for each plant. 

The argument for a fast cut is dominated by the fact that most people think it is neater.  It drives some folks crazy to have any part of their landscape appear unmanicured.  Other reasons to prune back freeze-killed esperanzas, annual flowers, lantanas and other plants as quickly as possible include the argument that many of us have more time now for gardening than we will have in the spring.  Save the springtime for planting.  Some gardeners also like to fill unused space with winter annuals such as pansies.  You may also already have larkspurs, daffodils and columbines naturalized.  They certainly grow and bloom better if the lantanas and plumbagos with which they share the bed are cut back early in the winter so the winter plants have access to the available light and space. 

            Those are good reasons to prune the damage quickly but there are other equally good reasons to delay pruning where it is possible.  The best compromise might be to treat each bed or plant separately and time the cut based on what is best for the plants in the bed and your goals for the planting.  Here are some reasons to delay the pruning of freeze-damaged foliage:

 

1.      The browned foliage and stems provide protection for lower unfrozen stems in the interior of the plant.  If you cut the frozen upper foliage immediately, the unprotected and as yet unfrozen stems in the interior of the plant are more likely to be frozen by the next freeze.  This is an important consideration if you feel it is desirable to preserve as much wood as possible so you have a larger summer esperanza or firebush.  In a mild winter, peńtas may not be completely killed if the lower stems are protected by the upper foliage.

 

2.      Our winter weather is erratic.  A sunny warm spell will often stimulate new growth from plants that then become very susceptible to more severe freeze damage as the winter progresses.  This is especially true of plants that did not harden off before the first freeze and are in a growth mode.  Plants pruned back to green wood are more likely to initiate new growth.

 

3.      If one of your desires for your landscape is to attract wildlife, the frozen foliage and stems are infinitely more attractive and useful to songbirds, insects and other wildlife than a bed trimmed to the ground.  The birds seek out insects and seeds in the winter landscape and the standing stems provide some shelter.  Annual flowers such as zinnias and sunflowers are especially useful to birds if the killed flowers are left.