×You have to get mud to cover some of the upper plates, since you can't stand in multiple places at once. Tar cannot do the job because then you wouldn't be able to get out again.

×Block the west blob with Beethro's body, so it stays 2-by-2. When the tar grows, immediately go north to keep the baby beside the east blob.

×Block the east blob on the west side. The west blob will grow once, and the east blob will be blocked by you on the west side and a baby on the east.

Now cut the east blob holding your sword east, and then arrange the babies in a line by moving southwest and backing up. Move to (18,25); this will hold the babies in line, with one under the east blob. Just before the next growth, step west. The babies will prevent the east blob from growing.

From here you should have the east blob under control. Just kill one baby at a time to free up space for the mud to grow, until it blocks the east blob itself. At that point, you can let the west blob grow once and then cut it.