How to Grow Iron Blue
Matthiola incana
Your complete guide to growing Iron Blue.
📷 Wikipedia: FlowerWhen to Plant Iron Blue
Planting windows vary by USDA hardiness zone. Look up yours by ZIP code.
| Zone | Start Indoors | Direct Sow | Harvest |
|---|---|---|---|
| Zone 1 | May – June | July – September | — |
| Zone 2 | April – May | June – August | — |
| Zone 3 | April – May | June – August | — |
| Zone 4 | March – April | June – July | — |
| Zone 5 | March – April | May – July | — |
| Zone 6 | March – April | May – July | — |
| Zone 7 | February – March | April – June | — |
| Zone 8 | February – March | April – June | — |
| Zone 9 | January – February | March – May | — |
| Zone 10 | January | February – April | — |
| Zone 11 | January | January – March | — |
| Zone 12 | January | January – March | — |
| Zone 13 | January | January – March | — |
Companion Plants for Iron Blue
✓ Good companions
Repels ants, aphids, and flea beetles more effectively than many chemical repellents
Repel aphids and Japanese beetles while improving soil health
Attract beneficial predatory insects and provide habitat for pest controllers
Repels moths, fleas, and mosquitoes while attracting pollinators
Repel nematodes and aphids while attracting beneficial insects
Act as trap crops for aphids and cucumber beetles, protecting nearby plants
Natural pest deterrent against aphids, tomato hornworms, and squash bugs
Attracts beneficial insects like lacewings and hoverflies for natural pest control
✗ Keep away from
Produces juglone toxin that inhibits growth and can kill sensitive flowering plants
Releases allelopathic compounds that suppress growth of nearby plants
Inhibits growth of most garden plants through allelopathic root secretions
Compete aggressively for nutrients and water, may stunt growth of smaller flowers
