Have large cedar hedge close to 8 ft. tall. We would like to replace three of the trees in the middle of the run. How would this be done? Would it be harmful to the other trees to the side of them and what size would the roots be? I can see close to the surface there is a spread out mass of roots, but how deep does this go? We are in Oakville, good soil, full sun, and we water. Thanks.
Thank you for contacting the Toronto Master Gardeners with your question.
8 foot cedars in the middle of a run can be replaced with minimal damage to surrounding members but it also depends on how many roots can remain undamaged. Usually cedars of this size in a maintained hedge refrain from growing thicker lateral roots which spread out into neighboring cedars. They tend to have more fibrous surface roots and some thicker roots going deeper. This is the norm but also depends on soil conditions and how many year the cedars have existed there. If they have been there more than 3 years, you will likely have to dig down 3 to 4 feet for removal, and may have roots as thick as 4 inches in diameter.
If you are digging up a neighboring cedar, you would want to avoid digging and disturbing roots under the ‘drip line’ of the neighbor that you want to retain. So as you are digging and you find root that might travel out from the cedar you are removing into the drip line space of the neighbor, then use a lopper or pruner to cut the roots off, rather than digging into the space of the neighbor.
Also sometimes it is a good idea to gently tie up the surrounding tree you want to protect from wielding digging tools with a twine or burlap.
Here is some general information on growing healthy cedars from a few of our earlier posts:
Watering deeply and thoroughly (at least once or twice a week after planting, especially in these hot summer conditions) is key so that your cedars’ roots can take hold and spread. This is much more effective than frequent spraying or light watering, and can be done easily by using a soaker hose along the base of the cedars for several hours to ensure that the moisture reaches into the roots of the plant. Watering should continue well into the autumn until the ground is frozen to maintain adequate moisture through the winter. Cold winter winds can desiccate the foliage – once the ground is frozen, your cedars cannot take up moisture to replace what is lost from their foliage.
Deep, thorough watering can also help the roots in the root ball to separate and penetrate into the soil after planting: plants that have been in their containers for some time can often be root bound – that is, their roots circle around the pot and are quite tightly packed. If you did not loosen, tease out, or separate the roots somewhat before planting, your cedars may be experiencing some stress as the roots move into the garden soil.
Fertilizing the hedge with a 30-10-10 formulation three times in the growing season (May, June and July) is appropriate. It is very important to follow exactly the directions for applying fertilizers so that they are absorbed into the soil and are able to reach the plant’s roots. Don’t fertilize in late summer as the hedge needs to prepare to go dormant for the winter.
Using a mulch over the roots ensuring that the mulch is kept at least 3 inches away from the trunk. This will help maintain a consistent level of moisture for root survival.
Good luck with your removals and replacements.