Grub up
Definition 1 of 2
Pro Tip 1/3Outdoor action
Usually involves physical effort, often used when describing garden work or farming. 
Every spring, Dad goes out to grub up the garden for new planting.
Pro Tip 2/3Total removal
Implies that you remove something completely, leaving nothing behind. 
After the storm, the cleanup team had to grub up fallen trees.
Pro Tip 3/3Prepare for new
Used when making space for something new by removing the old or dead plants. 
To plant the new seeds, first, you need to grub up the weeds.