To cut taller hedges you will need ladders but these days there are many hedge trimmers on the market that are designed to make life simpler. You can opt for petrol trimmers, electric (corded) ones or ones like this 24v battery operated Greenworks’ Long Reach Hedge Trimmer. When purchasing battery-operated products you often need to purchase the battery and charger separately, which can bump up the cost, but these can also be used with other products from the same company.