What companion plants benefit asparagus growth?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Asparagus can be healthily and naturally grown with strategic companion planting. Companion plants can repulse pests and attract beneficial insects. Tomatoes are naturally rich in solanine, which will repel the asparagus beetle. Parsley will attract predatory insects that will eat the harmful insects of asparagus. Basil will hide the asparagus smell to confuse asparagus pests. Avoid aggressive alliums, such as onions and garlic.
Pest-Repelling Companions
- Tomatoes: Emit solanine deterring asparagus beetles
- Marigolds: Release compounds that repel nematodes
- Nasturtiums: Deter aphids and striped cucumber beetles
- Basil: Masks asparagus scent confusing flying pests
Beneficial Insect Attractors
- Parsley: Lures parasitic wasps that eat beetle larvae
- Dill: Attracts ladybugs consuming aphids
- Cilantro: Brings hoverflies feeding on thrips
- Fennel: Draws lacewings controlling mite populations
Plants to Avoid
- Onions: Compete aggressively for nutrients and space
- Garlic: Inhibits asparagus root development
- Potatoes: Share similar fungal disease risks
- Root vegetables: Disturb shallow asparagus roots
When to Plant Companions for Optimal Benefit? Sow seeds for parsley and basil two weeks before the asparagus comes up. Plant tomatoes in the garden after the last frost has passed. Doing so allows for protection when pest dynamics are the toughest. Properly space out your plants to avoid competition around the asparagus plants.
Companions greatly reduce pesticide usage. Studies of tomato interplanting found similar levels of beetle damage with interplanted plants at only 30% damage, while stand-alone plants were normally at 90% damage. Beneficial insects utilize parsley and control 85% of larvae naturally. This creates an ecosystem balanced with the least amount of intervention required. Healthier plants are better able to resist disease.
Use companion rotation for continuous benefits. Switch companion plants, such as marigolds with nasturtiums along the edge of the bed, or parsley with cilantro, yearly so that insects do not get adapted. This can help maintain confusion for the pest, as well as a healthy soil.
Companion planting, when practiced over the long term, improves soil quality. Deep-rooted tomato plants will break up the subsoil. Partners like the nitrogen-fixing parsley will enrich the soil. The accumulation of these benefits means decades of productive asparagus production with reduced fertilizer use. Your work that first summer becomes a self-sustaining system.
Read the full article: How to Grow Asparagus from Crowns Successfully
