Overwintering Boston Fern and Asparagus Fern in Oklahoma

Boston fern (Nephrolepis exaltata) and asparagus fern (Asparagus densiflorus ‘Sprengeri’) are both Zone 9 plants that need protection in Oklahoma winters. A home greenhouse or bright indoor window can work.

Asparagus Fern

• Keep in a bright, cool window (east or south).
• Water occasionally to slow growth.
• May produce fragrant spring flowers.
• Not a true fern—related to edible asparagus.

Boston Fern

• Same light and temperature conditions.
• In spring, divide root ball into individual plants and repot.
• Longer days trigger rapid growth for summer use.

General Rules

• Water with discretion—never let pots sit in water.
• Zero fertilizer all winter.
• Monitor for pests like spider mites in dry indoor air.

Both plants can thrive with minimal care if kept cool, bright, and barely moist. They’ll reward you with lush growth next season.