To Trim or Not to Trim?

Lisa's Landscape & Design ♦ 12/27/2012 ♦ 2 Comments

This is a question I hear often and it is has an important answer. There seems to be a lot of confusion when it comes to Fall /Winter trimming  and I know from my own experience that most trimming done in the Fall/Winter is not done for the right reason.

Landscape companies have little work off-season, so they want to convince you  that you need to cut back and mulch in the fall/winter months. While the mulching part is accurate the trimming part is simply not true. I have been doing gardening/landscaping both professionally and personally for over 20 years in Central Texas and  I can tell you most fall trimming is a bad idea. The only reason you would trim deciduous perennials (returning plants that go dormant in the Winter) in the fall is for aesthetics, for example, most commercial properties and HOA’s do not leave dying leaves and plants untrimmed over this season for visual reasons only, it’s not done for the health of the plant. Of course evergreen shrubs that are intended to have a shape can be trimmed all year as needed, but if they are a flowering evergreen shrub, late fall/winter trimming is discouraged to avoid the loss of spring flowers.

The healthiest way to go about it is to embrace the winter landscape and allow the plants to hold onto their dead leaves and branches for protection from the harsh weather. If you have lived in Austin Texas for more than a day, you probably know we can go from summer to winter and back again in less than 24 hours, it is hard enough for us to figure it out, imagine how your plants feel. Trimming your flowering perennials encourages new growth so you may be encouraging your plant to grow back too soon during a warm spell. Wait until the early Spring when you see the first signs of green and trim back then. Keep a garden journal identifying each plant so you remember where dormant plants were and you know which plants not to trim at all. Most woody plants need nothing trimmed but the very ends but you wont know that if you do not allow them to green up first.

When it comes to shaping flowering shrubs, flowering trees and fruit trees, (see diagram)trimming should be done as soon as they are done fruiting or flowering for the season.  Cutting these plants back in the Winter simply means that you have cut off potential fruit and flowers for the next season as these plants already have produced the buds for the Spring season by fall. The main objective here, as with large trees is to remove the dead wood and suckers from the trunk and to clear out the center branches so that air can flow freely preventing disease and allowing light once the leaves return. Never trim back the center or main leader stem too harshly as you can damage, distort or kill the tree this way.  A trim back to pencil width on the center stem is typically safe on most trees. Avoid trimming saplings (baby trees) where they will grow (2) main stems, this makes for a weaker tree, you want one main stem and several branches coming off of it in several places. (see example)

This tree split due to the burden of weight distribution, best to have one main trunk with branches coming off of it.

Roses should be trimmed and dead headed all year as needed, but winter is a great time to do your hard pruning,  (January is best.)  Hard pruning helps stimulate a strong root system and stimulate the new Spring growth. This is again a case when pruning too late will mean you have cut off the buds for the spring season. Most roses will tolerate a pretty significant cut back and this is the time to cut out all the dead and overgrown wood.  Hard pruning Climbing Roses can kill them so only cut the dead wood and leggy branches from them.  If they are terribly overgrown, only cutback to about 4′ or so, never to the ground.  If your roses have black spot or fungal issues, carry a plastic bag with you to collect the leaves and clean up around the ground being careful to remove all diseased leaves, bag them and throw them into the garbage so they are not spreading on next year.

Large deciduous and evergreen trees can really be cut most times of the year. Oaks are especially important to spray when cutting to avoid Oakwilt, but most others do not require you to do so.  Spray the Oak with a tree sealant found at most nurseries. The recommended trim schedule for Oaks is during the hottest and coldest months, but if you need a trim the rest of the year, or are not able to get to it until then, ALWAYS cut and spray regardless of the time of year.  (For more info on Oakwilt see  http://lisalapaso.com/2010/02/04/oak-wilt/)Other trees need to have dead wood and parasites such as Mistletoe cut out from the tree, also shaping and removing suckers (example)

Tree “suckers” are the little stems that sneak out on the trunk of the tree. Remove those as they drain from the tree and serve no purpose.

from the trunk of the tree can be cut off all year.  (Mistletoe is easiest to find when the tree looses it leaves in the winter (Google tree parasites for other info on this topic)  Clearing the center of the tree in large amounts should only be done during the cooler months.  Removing too many branches or leaves in the hot summer can literally give your trees bark a sun burn.  Another reason to trim large trees is to raise the canopy which can prevent injury to people, homes and nearby trees. By removing dead wood and clearing the center of the tree, you allow it to breath and receive sunlight which decreases the chance of disease and fungus. (this is also true for Roses)

One of the tricky plants to trim is ornamental grass.  Grass need to be trimmed after they turn brown,  You cut them back  into a bun shape after they turn completely Brown but before they start to send out new green blades. Cutting the dead material back allows the new blades to penetrate the dead blades and reach for the sunlight. Cutting back too late can cause a separation of the new blades creating large empty spaces in your large ornamental grasses and those dead centers will not fill in leaving the grass looking sparse and frankly rather unattractive. Ornamental grass grow from 6″ to 12′ tall and you need to be especially careful with certain ornamental grass as some of the blades are as sharp as a razor if you rub them the wrong way ( sort of like some people we know 😉  Always wear protective gloves and long sleeves when cutting back your tall grasses.

Actually, having the proper equipment for all of these jobs is sooo important. Use good gloves, wear sturdy shoes and always use really sharp tools to cut and trim. Trimming with dull tools causes tearing to the bark and can promote disease. You also want to clean your tools with Lysol before going from rose to rose to prevent the spread of Fungus’ (this is also true with Oaks)

So mulch your beds this fall, then take a break from your garden and enjoy the holiday’s with your family, snuggle a bit…, take a walk through your garden and notice the fall and winter landscape through new eyes and watch with anticipation as your inevitably green leaves, buds and blades reappear in the spring, then…you have your work “cut” our for you 😉

Happy Gardening!!

Lisa LaPaso

Lisa’s Landscape & Design ( ” like” me on facebook)

“Saving the Planet One Yard at a Time”

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