The best time is spring or autumn. Look for healthy, semi-hardwood stems that grew this year. They are slightly firm at the bottom but still soft at the top. A simple test: gently bend it; if it's flexible but doesn't snap immediately, it's perfect! Cut a branch a few inches long, and remove the bottom leaves- it only needs a few leaves at the very top to survive- less is better!
In this example, we cloned lavender. Lavender roots dislike overly wet conditions, so it's crucial to choose a well-draining medium. You can mix soil and sand in a 1:1 ratio, fill your seedling tray with the mix, and water it thoroughly to moisten the soil. If you're using a different plant, check what type of soil conditions it prefers.
To boost your success rate, I highly recommend using a rooting hormone. Dip the cut end of the stem into the powder and let it dry slightly.
Insert the prepared cutting into the moist soil. You can use your finger to gently make a small hole in each cell of the tray, then place the cutting inside and gently secure it with the surrounding soil.
Place the seedling tray in a bright, airy location, but keep it away from direct sunlight. To maintain humidity, you can use a clear humidity dome. When your small lavender plants start to grow new shoots, congratulations, your cloning mission is a success! Typically, the cuttings will begin to root in 3-4 weeks.