You can propagate your arborvitae plant by stem cutting, and I highly recommend doing it in late summer or early fall! To get started, you'll need a few tools. I recommend having a sharp pair of scissors or a knife, some potting mix, a pot, rooting hormone, and a clear plastic bag or dome. Here's how you can do it: 1. Now, take a healthy, mature stem about 4-6 inches long and make sure it has some leaves. Remove the leaves below the cutting, about 2-3 inches. 2. Let's prepare this cutting for its new home by dipping it in rooting hormone. 3. Now for the fun part! Plant your cutting in a well-drained growing medium. 4. It's essential to create a pleasant, humid environment and give the plant all the love it needs to thrive!