When the black hole is about to appear, a message will appear, saying, "The temporal black hole is about to absorb your plants!" The black hole will always appear at the first lane from the left, and will move all plants one column to the right. Plants which are placed at the column where the black hole appears beforehand will also be sucked in. Both planting and recharging plants are disabled when it appears until it disappears completely. The hole's pulling force can be blocked by White Radish.
Whenever playing these levels, it is highly recommended that you always bring White Radish, as without it, the player may risk losing your plants either by the hole or being eaten by the zombies, since the plants will be pulled closer to the horde. Plant a whole column of them to be safe, and upgrade it if necessary.
Avoid planting Spikeweeds and Spikerocks, as they are also pulled by the portals and the White Radishes cannot protect them. Also, it is wise to avoid using Potato Mine, since to use it effectively, it must be planted in front of your White Radishes, and thusly, be at risk of being sucked into the black hole. Do note that unprotected chestnuts from Small Chestnut Teams can also be pulled.