Two years ago I planted four foot cedars,this spring they are dry
And a dull green,help.
Thanks for contacting the Toronto Master Gardeners about your dry four-foot pyramidal cedars (Thuja occidentalis ‘Smaragd’). Your concern is not uncommon for people growing these trees.
Emerald cedars are very attractive plants that are readily available for use as specimen plants or hedging; they are inexpensively priced. However, one must be aware that these cedars prefer a climate with consistently cooler temperatures and a lot of rainfall (moisture); these trees are easily grown in B.C. from where they are shipped to urban areas (such as Toronto) in the spring. [Even though many of these cedars are grown in B.C., some are grown Ontario and may transplant more easily; those that are grown in B.C. may not adjust well to the different climate no matter what one does]. Once planted, they must be watered consistently/constantly during the first year to: (1) compensate for the higher summer temperatures and general drought conditions in the Toronto area and (2) help get the root systems established. Most importantly, watering must continue throughout the fall months until the ground freezes; cold winter winds will desiccate the foliage if the plants have not been adequately watered before the ground is frozen.
Make sure that when you water, water deeply and thoroughly at least a couple times each week especially during the summer, to ensure that the roots have adequate water. Using a mulch under the plants will also help to maintain moisture in the soil.
Since you describe your cedars as a “dull green” instead of brown, perhaps they can be revived. Please see this Toronto Master Gardener response for other considerations in helping to maintain your Emerald cedars: https://www.torontomastergardeners.ca/askagardener/dying-and-browning-emerald-cedars/.
Depending upon what happens in the next while, you may decide to replace them. You might consider other alternatives that will not require so much maintenance. See:https://www.torontomastergardeners.ca/askagardener/replace-emerald-cedars-with-something-else/
If you have any other questions, please get in touch with us. In the meantime, good luck with your cedars.