Hi there - the rough rule with bulbs or corsm is for them to have twice the depth over them as their height, so a biggish glad would go in a three inch deep hole.
Underground slugs love glads and sometimes the base plate can rot off, so it's worth putting a bit of grit in the baottom of the hole, so make the hole a tad deeper to accomodate this.
They go in base plate down of course hahahahah you knew that.
If they are ones with massive spikes you are going to stake it is worth putting the stakes in as you plant the corms as this saves accidentally damaging the corm later on.
Once they have doesd down in the autumn you can digh them up and dry them off for the next year... where you are in Hull it might be a bit cold for them to survive in the ground.
Hope that helps.They can make a great display
