Making space for new growth is the key to securing your summer garden, but with so much ready to prune, it can be tough to know where to start. Whether you’re growing shrubs, grasses or a mixture of vibrant flowers the seasonal transition is the perfect time to give your plants some TLC. Express.co.uk spoke to award-winning garden designer Polly Wilkinson to find out exactly what you should be doing in your garden this March. What to prune in March While spring has arrived in the meteorological sense, the new season will not officially set in until the end of the month. This three-week transition between winter and spring is the perfect…