I live in Niagara Falls and I planted over 20 emerald cedars about a month ago – half of them are already brown (with a few dead). What am I doing wrong? My yard is full of white pines is my soil too acidic ?
Thank-you for contacting Toronto Master Gardeners with your question about your Emerald Cedars (Thuja occidentalis ‘Smaragd’).
We get a lot of queries about Emerald Cedars. They are popular plants and, unfortunately, they are susceptible to a number of problems. Here is a link to a previous answer to a similar question: https://www.torontomastergardeners.ca/askagardener/dying-emerald-cedars-3/
While these trees can fall victim to several pests and diseases over the years, the common problem with browning and dying off within the first season is caused by the way they are grown and brought to market. While they are native to Eastern North America, Emerald Cedars are often sourced from the West where they are grown on large tree farms. The trees are accustomed to a milder climate with more rain than we normally get in Ontario. They are cut out of the ground and placed into pots for transportation in bulk, and they are often sold quite cheaply in garden centres. Pot grown stock is a better bet (especially if grown locally) because the roots are intact and ready to grow into their new planting site. The roots of the trees that have been cut out of the ground may not be able to survive transplant shock and reestablish themselves fast enough to support the plant through the growing season and into the winter. Consistent, deep watering is really the only way to nurture your trees while they recover from transplanting and reestablish their root systems. You may be able to save some of them. Many garden centres have 1 year warranties, so you could look to getting replacements or a refund.
This is a brief overview of some of the issues that may be causing your newly planted cedars to turn brown; if you search on our “Ask a Master Gardener” website using the word “emerald”, you will find several other posts answering questions on Emerald Cedars on a variety of topics.
Best of luck with your cedars!