Native to South America, pampas grass is a perennial grass that grows in large clumps. At maturity, pampas grass reaches heights up to 10 feet, and the tall, billowy plumes add several more feet to this dramatic plant. Plumes may be silvery-white or pink, depending on the variety. An annual pruning keeps pampas grass looking its best.
Prune pampas grass in late winter to remove old growth, allow light and moisture to enter the center of the clump and clear the way for healthy new growth. Although the plant can be pruned in autumn, pruning in late winter allows you to enjoy the interesting appearance of the dry plant throughout the winter months. After early winter, new growth appears and pruning becomes more difficult.
Pampas grass is a formidable plant, measuring up to 6 feet in diameter. Sturdy tools such as electric power pruners or hedge shears make the job more manageable. You can also use long-handled shears or tree loppers. Always wear sturdy clothing, including long pants, long-sleeved shirts and gloves, because the dry blades of pampas grass are sharp enough to make painful cuts. For large, overgrown clumps, a chainsaw is helpful.
Cut pampas grass to about 10 to 12 inches in height. To prune the plant with hand clippers, cut it in small sections, beginning with the outer perimeter. Use your gloved hands or a rake to clear out the pruned grass and old leaves, and then prune the next section. If you're using power pruners or a chain saw, tie heavy twine around the clump about 15 inches from the ground, and then cut the plant 2 to 3 inches below the rope.
Discard of the pampas grass prunings in the garbage or haul them to a landfill. Don't attempt to compost the pampas grass because the lightweight spores blow in the wind and may redistribute the plant over a large area. Feed the newly pruned pampas grass lightly with a balanced granular fertilizer to encourage healthy new growth. Apply the fertilizer according to the specifications on the label, and then water the pampas grass deeply after fertilizing.