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Conifers/cedar hedge


Hi Jim, i asked you a question in 2011 and im back. I live in the southern part of Quebec and have a nice cedar hedge that is growing nicely, some of the hedge has reached the height i like (approximately 8 to 9 feet) and some parts are only 5 feet high. Last year i started putting fertilizer in the hedge and every year i try to learn more about cedar hedges. I need to know when is the growing stage and dormant stage of the hedge and what type of fertilizer strenght to use in what periods and when to cut the hedge for the last time before fall arrives.I will tell you what ive been doing and told so far and tell me if this is correct please. The snow finishes melting in mid to late april and in the past week i can tell that the hedge has started to grow. I have a seeper hose everywhere under the hedge and have started watering it since the snow has melted and try to give it a good watering once a week.I have been told that the growing stage is from may to late june or early july(is this true). During the growing period i can give it fertizer and was told not to use one with a high nitrogen amount because the plant will grow in height with small leafs instead of growing thick(?????)What strenght should i use? Last year i used an 18-4-6 hedge fertilzer. Next, i was told to cut the hedge right after the growing stage, early july, so that the branches have time to heal before winter. Last year i cut my hedge for the last time in early august. The reason i cut it in august was because i was noticing that the hedge was still growing. Can the hedge continue growing a while after its "growing period" has finished?When should i cut the hedge for the last time? (i also give it a trim in late may early june to keep it nice) Afterwards, i still continued watering the hedge up to winter time but did not fertilize it after its growing stage. I was told that i could give it some fertilizer after the growing stage, a fertilizer with a higher nitrogen value, however when or why i am not sure?The trees which have achieved the desired height are thick and furnished whereas the shorter trees are thinner and less furnished??

thanks Bruce

Cedars are a very hardy tree or shrub that often does very well without fertilization. However, fertilizing your cedar can help to encourage more rapid, healthy growth. The type of fertilizer you need will depend on how recently you have planted the cedar and the type of soil in which the cedar grows.

The best fertilizer for your cedar will depend on the type of soil your tree grows in. Many cedars prefer a more acidic soil. Before fertilizing, test the soil acidity with a pH test kit. PH test kits are available at many Garden type stores.

Fertilization should be with a balanced fertilizer or with a higher nitrogen fertilizer with a balance similar to 30-10-10. The 18-4-6 fertilizer is good. You want more Nitrogen than the other elements. The first number is the Nitrogen. Higher nitrogen levels after the tree is established will help produce more green growth on the tree or shrub.

Apply around mid-spring, around the time that flowers and other trees start to bloom. Spread the 18-4-6 granular fertilizer onto the soil using the amount specified for the square footage of the cedar hedge. Reapply the same amount of fertilizer to the cedar hedge in June and in July. Be sure to water well after each application.

Water the soil well with a garden hose immediately following the fertilizer application until you no longer see any granules on the surface of the ground.

Plants have the major spurt of growth in the spring but will continue growing until Fall. Your method of trimming sounds about right to me. Pruning in the spring and trimming as needed during the year. Shape the hedge in early autumn only if necessary, but be careful not to prune the bush too deeply. Open or sparse areas left inside the hedge can open it up to problems if the winter is particularly brutal and cold. Delicate branches that havenít had enough time to strengthen and grow may crack, resulting in serious damage inside of the bush.

I hope this answers most of your questions.  


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Jim Hyland


Registered Forester in the Southern US with 30 years experiance in managing pines. Expert in pine forest health from management to control of pests to ID of species.

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