Answer: Unfortunately it sounds as though your little trees are very stressed. They are native to regions with cool summers and cold winters so the extreme heat in the city during the summer is a problem for them. They also need a an evenly moist yet well drained soil meaning damp like a wrung out sponge, never sopping wet and never dry. Container plants tend to dry out quickly so this can sometimes mean watering as often as once a day in the heat of summer. Then they are also occasionally subject to fungal infections and to infestation by spruce spider mites as well. Spider mites can be washed off with a strong spray of water from the hose once a week (if you have one on the patio?), or you can use a commercially formulated insecticidal soap per the label instructions. Here is some information about these.
Based on your description I am not certain which of the above have happened, possibly a combination of factors. You might consult with your local Cornell extension for help in troubleshooting, or with your local professionally trained and certified nurseryman, and see if they can be saved. I'm sorry I can't be more encouraging.
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