Pots are essential to the character of every part of the garden at my home, Perch Hill. Get the pots right and the garden will take on an ebullient, cheerful energy of its own. There is one cast-iron rule with pots: more is more. I’ve just had a walk round the garden and counted 382 of them. Forty-eight whoppers, all about 60cm tall and wide, including six large water troughs; 160 medium-sized containers, an average of 50cm x 40cm; and a bevy of small pots, 15cm high or less. I’m not saying…