I have just planted a dozen DeGroot Cedars. I have no idea if I am under watering or overwatering. Although I did dig out the holes and added triple mix, the surrounding environment is Clay and I am not sure how much water may be retained underground. Please advise.
Thank you for contacting Toronto Master Gardeners. We receive many questions about cedar care. Below are some links to previous responses that contain useful information on watering and general care of cedars.
Thuja occidentalis ‘Degroot’s spire’ is very popular as a means of creating a dense hedge. Providing too little or too much water just after planting will certainly have an impact on the overall growth of your new cedars.
Cedar prefers growing in average to moist conditions and shouldn’t be allowed to dry out. Moist, organic soil that drains well is best for good growth. Cedar’s dislike dry sandy soils, as well as excessively moist clay soils. To help concentrate water in the area of the roots and avoid runoff, create a 3 ins mound of soil in a circle around the trunk at the outer edge of the root ball. The amount of water applied depends on a variety of considerations. Factors such as weather and good drainage will make a difference. Checking the soil before watering is a good idea. To test, poke a small hole with your fingers into the ground near your plants. If dry it’s time to water. (You will need to go down 2-3 ins). A thorough watering rather than frequent light sprinklings is best, because the latter tends to induce shallow roots thus making the plants more susceptible to drought. It is important to apply the water over the whole area of the root system. The use of a soaker hose is an ideal way to do this. Watering once or twice a week in the beginning should be sufficient. If you test water as necessary.
Applying mulch around the root zone of your plants will help conserve water and protect them from the freezing and thawing cycles of winter. Keep the mulch about 2-3 ins from the trunk. For the first winter it may be a good idea to protect your plants from winter winds by wrapping burlap around them.
Bear in mind that overwatering is just as detrimental to your plants as underwatering.
Links:
https://www.torontomastergardeners.ca/askagardener/dying-and-browning-emerald-cedars/
https://www.torontomastergardeners.ca/askagardener/dying-emerald-cedars/
Hopefully some of these ideas will work for you and your cedars will survive their first winter.