Methods, systems and apparatus for effectively erasing blocks with few programmed pages are provided. In one aspect, a system includes a memory and a controller coupled to the memory. The memory includes blocks each having pages. The controller is configured to determine whether a threshold page with a particular page number in a block of the memory is programmed, to erase the block according to a normal erase action in response to determining that the threshold page is programmed, and to erase the block according to a particular erasing action that is configured to erase the block deeper than the normal erase action in response to determining that the threshold page is not programmed. The particular erasing action can include pre-programming the block before erasing the block, decreasing an erase verify voltage before erasing the block, or adding one or more erasing pulses with a new erasing voltage.