12/09/2014 at 12:08
Totally depends on the size of bulb peter, and they can vary enormously. Four inches or so will suit smaller daffs, but would be too deep for crocus, and too shallow for most lilies for instance. Bob's description is the way to go - you won't go far wrong if you follow that.
In pots you can plant more closely together, and also less deep as it's a different medium altogether, and many people feel tulips will perform and survive better if they're planted more deeply than the recommended 'twice the height' system