The answer to 'hedge not growing' is that there are several common causes, including improper planting, lack of water, pests or diseases, and improper pruning. Symptoms may include stunted growth, yellowing leaves, or bare patches in the hedge. To address this, you'll need to first identify the root cause and then take the appropriate steps to correct it.
If the hedge was recently planted, make sure it was planted correctly at the proper depth and given enough water during establishment. Established hedges may need more frequent watering, especially during hot, dry periods. Check for pests or diseases that could be stunting growth, and treat accordingly. Improper pruning techniques can also prevent a hedge from filling out, so be sure to prune at the right time of year and use the correct methods.