Eradicating Invasive Asparagus Fern: Digging, Smothering, or Herbicide

Know Your Enemy

Asparagus fern (Asparagus densiflorus 'Sprengeri') isn't a true fern—it's a tough, tuberous perennial with an extensive root system and thorny stems. Once established, it spreads aggressively via roots and bird-dispersed berries. Complete removal requires persistence.

Method 1: Digging (Fastest, Most Thorough)

• Cut all top growth to ground level.
• Dig out the entire root mass, including tubers. Go deep—roots can extend 2+ feet.
• Sift soil to remove tuber fragments; any piece can resprout.
• Refill with clean soil. Monitor for months; pull any shoots immediately.

Method 2: Smothering (No Chemicals, Slower)

• Cut to ground. Cover area with cardboard/newspaper (6+ layers) + 4–6 inches of mulch.
• Leave for 12–18 months. No light = no photosynthesis = roots starve.
• Check edges periodically; pull any escapees.

Method 3: Herbicide (Glyphosate/Roundup)

• Cut back in late summer/early fall when plant is moving energy to roots.
• When new shoots are 6–12 inches tall, spray glyphosate per label (typically 2% solution).
• Add surfactant for better leaf penetration.
• Shield desirable plants with cardboard; avoid drift.
• Repeat in 2–3 weeks if needed.

Paintbrush method: For spot treatment near other plants, pour concentrate into a jar and paint onto cut stems/leaves. No spray drift.

Disposal

Never compost roots, tubers, or berries—they survive. Bag and trash, or burn where permitted.

Prevention

• Don't plant asparagus fern in ground unless contained by deep barriers.
• Deadhead berries before they ripen.
• Monitor property lines; it spreads from neighbors.

Digging is the only sure one-time fix. Smothering works if you have time. Herbicide is a tool, not magic—follow label exactly. Whichever you choose, vigilance for 2+ years is non-negotiable.