Cedar hedges can grow rather quickly and in order to keep the hedge healthy and looking its best it is advised that you trim the hedge two times per year.
Preparing to trim your cedar hedge
Hedge trimming can be done at the same time of year as your spring garden clean up. Cedars are often filled with branches, dead needles and leaves that have fallen from trees above. Before starting your spring cedar hedge trimming I would advise that you use a blower if you have one on hand. A leaf blower is very helpful for cleaning out the build up of dead debris and needles. Alternatively, you can also shake the individual hedge trees or tap the sides of the hedge with the back of a rake in order to shake the unwanted debris trapped inside the structure of the hedge down to the ground. This first step is often missed but can make a huge improvement to the health and look of your cedar hedge. Removing this internal debris allows light to penetrate and will increase growth of new needles. Once you’ve shaken out the debris, remember to get all the build up of debris at the base of the hedge removed.
Planning the cut
Stand to one side of your cedar hedge and look down the line of the hedge to determine how you will shape the hedge. Cedars can ONLY be trimmed into the green growth. You cannot cut branches beyond the green needles, as it will not grow back. Cutting into old wood where there is no growth is a common mistake. Cedars only hold a few years of growth on the ends of their branches. If you cut beyond this growth area, you will end up with dead branches where there should be a hedge.
If left unkempt, cedar hedging plants such as the popular Thuja occidentalis ‘Smaragd’, or Emerald cedar, will grow to a height of 15-20m after 15 years. Be sure to maintain the shape and size of hedge you want in your yard by trimming at minimum once per year, though ideally twice for a manicured look.
Once you have cleaned out the inside of the hedge you can start with the trimming of the cedar hedge. If you are using a gas or electric trimmer make sure that you are wearing safety protection (eye glasses especially) and gloves. I also recommend you wear long sleeves and long pants as cedars can easily cause skin rashes on most people.
Start trimming on the right hand side of the hedge and work your way to the left. Trimming a cedar hedge takes patience, as multiple sweeps with the trimmer may be required in order to cut the leaves at the correct spot. Remember to keep your elbows in to your sides to reduce the stress on your body when you are trimming. If you have a hedge that has grown taller than you feel comfortable trimming yourself you may want to contact a professional hedge trimmer to help you with the project.
When to trim your cedar hedge
Trimming your cedar hedges in May and October is an economical way to keep your hedgerow looking tidy. In spring, after new growth has flushed out, you will maintain your desired shape as well as prevent the hedge from getting too big for your yard. Trimming again in October allows you to cut back any new growth from the summer months, and gives you a neat looking hedge for the duration of winter.