Iron Marine
Matthiola incana
Photo: Svencapoeira · Wikimedia Commons · (CC BY-SA 4.0)
Early single-stem, or column-type stock in a highly uniform series for one-cut harvest. Aptly named for strong, straight, rigid stems. Iron performed well in our spring, early summer, and fall trials. Selectable for doubles and 55% double without selection. Compared to Katz, Iron is slightly later to flower, and has somewhat shorter and thicker stems. Tightly spaced florets on the flower spike make for compact 1 1/2-2", pale lavender-blue blooms with a full appearance. NOTE: This variety produces one flowering stem per plant. Pinching is not advisable as it will terminate flowering. Edible Flowers: The peppery, clove-like flavor of the flowers lends itself well to use as a garnish on salads, desserts, and drinks.
Harvest
90-105d
Days to harvest
Sun
Full sun to partial shade
Zones
6–10
USDA hardiness
Height
1-3 feet
Planting Timeline
Showing dates for Iron Marine in USDA Zone 7
All Zone 7 flower →Zone Map
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Iron Marine · Zones 6–10
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | April – May | June – July | June – August | — |
| Zone 4 | March – April | June – June | June – July | — |
| Zone 5 | March – April | May – June | May – July | — |
| Zone 6 | March – April | May – June | May – July | — |
| Zone 7 | February – March | April – May | April – June | — |
| Zone 8 | February – March | April – May | April – June | — |
| Zone 9 | January – February | March – April | March – May | — |
| Zone 10 | January – January | February – March | February – April | — |
| Zone 1 | May – June | July – August | July – September | — |
| Zone 2 | April – May | June – July | June – August | — |
| Zone 11 | January – January | January – February | January – March | — |
| Zone 12 | January – January | January – February | January – March | — |
| Zone 13 | January – January | January – February | January – March | — |
Succession Planting
Stock doesn't keep producing after its first flush — once it blooms and sets seed, it's done — so succession plantings are worth the effort if you want cut flowers across multiple weeks. Start seeds indoors in late February, then again in mid-March; transplant the first batch in April and the second in early May (zone 7). Direct sow is possible through June, but daytime highs above 85°F cause heat-induced bolting without good spike development, so there's a real cutoff around mid-June in the Southeast. Three staggered plantings of 10-12 transplants each will carry you from late May into July without a gap.
Complete Growing Guide
Early single-stem, or column-type stock in a highly uniform series for one-cut harvest. Aptly named for strong, straight, rigid stems. Iron performed well in our spring, early summer, and fall trials. Selectable for doubles and 55% double without selection. Compared to Katz, Iron is slightly later to flower, and has somewhat shorter and thicker stems. Tightly spaced florets on the flower spike make for compact 1 1/2-2", pale lavender-blue blooms with a full appearance. NOTE: This variety produces one flowering stem per plant. Pinching is not advisable as it will terminate flowering. Edible Flowers: The peppery, clove-like flavor of the flowers lends itself well to use as a garnish on salads, desserts, and drinks. According to Johnny's Selected Seeds, Iron Marine is 90 - 105 days to maturity, annual, open pollinated. Notable features: Use for Cut Flowers and Bouquets, Edible Flowers, Fragrant.
Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: Clay, High Organic Matter, Loam (Silt), Sand. Soil pH: Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 3 ft. 0 in.. Spread: 0 ft. 9 in. - 1 ft. 6 in.. Spacing: Less than 12 inches, 12 inches-3 feet. Growth rate: Rapid. Maintenance: Low. Propagation: Seed. Regions: Coastal, Mountains.
Harvesting
Iron Marine reaches harvest at 90 - 105 days from sowing per Johnny's Selected Seeds. Expect 1 1/2-2" at peak. As an annual, harvest continues until frost ends the season.
Seeds will ripen in August and September.
Harvest time: Fall
Storage & Preservation
Iron Marine stock flowers are best stored in a cool location between 34-40°F with moderate humidity, preferably in the refrigerator. Kept in water in a vase, they last 7-10 days at room temperature or up to 2 weeks refrigerated. For preservation: (1) Air-dry by hanging bundles upside down in a dark, well-ventilated area for 2-3 weeks to create dried arrangements; (2) Freeze petals individually on a tray before transferring to freezer bags for long-term use as garnishes; (3) Press flowers between parchment paper under weights for 2-3 weeks to create dried florals for crafts and decoration.
History & Origin
Iron Marine is open-pollinated, meaning seed saved from healthy plants will produce true-to-type offspring. Listed in the Johnny's Selected Seeds catalog.
Origin: The Coast of Europe from Spain to Greece.
Advantages
- +Strong, rigid stems ideal for professional cut flower arrangements
- +Highly uniform series ensures consistent quality for commercial one-cut harvest
- +Compact, full 1.5-2 inch blooms with tightly spaced florets look luxurious
- +Performs reliably across spring, summer, and fall growing seasons
- +Peppery clove-like flowers suitable for culinary garnish applications
Considerations
- -Single stem per plant limits yield compared to pinchable varieties
- -Slightly later flowering than Katz variety requires longer production timeline
- -Cannot be pinched without terminating flowering, reducing flexibility
- -Somewhat shorter and thicker stems may not suit all floral designs
Companion Plants
Marigolds (especially Tagetes patula) and Sweet Alyssum pull the most weight here — Tagetes patula pushes back on aphids and whiteflies chemically through root and foliar compounds, while Sweet Alyssum draws in parasitic wasps that reduce caterpillar pressure on nearby plants. Calendula and Nasturtiums work as trap crops, giving aphids something more appealing to land on than your stock spikes. In our zone 7 Georgia garden, Lavender is worth planting nearby — both want sharp drainage and 6+ hours of sun and their root systems don't fight each other. Black Walnut is a hard no: juglone moves through the soil and will stunt or kill Matthiola well before you figure out the cause. Fennel's allelopathic root secretions make it a poor neighbor for cut flowers generally, and stock is no exception.
Plant Together
Marigolds
Repel nematodes and aphids while attracting beneficial insects
Lavender
Deters pests with strong scent and attracts pollinators
Nasturtiums
Act as trap crops for aphids and cucumber beetles
Sweet Alyssum
Attracts beneficial insects like lacewings and hover flies
Petunias
Repel aphids, tomato hornworms, and squash bugs
Calendula
Attracts beneficial insects and repels harmful nematodes
Zinnia
Attracts butterflies and beneficial predatory insects
Catnip
Repels mosquitoes, ants, and various garden pests
Keep Apart
Black Walnut
Releases juglone toxin that inhibits growth of many flowering plants
Fennel
Inhibits growth of most garden plants through allelopathy
Eucalyptus
Releases allelopathic compounds that suppress nearby plant growth
Troubleshooting Iron Marine
What you'll see, why it happens, and what to do about it.
Gray, fuzzy coating on stems or buds, usually after a wet stretch in cool weather
Likely Causes
- Botrytis cinerea (gray mold) — thrives in humid, still air below 70°F
- Overcrowded planting that traps moisture around the crown
What to Do
- 1.Remove and bag any affected stems immediately — don't compost them
- 2.Thin plants to at least 12 inches apart and clear debris from the base
- 3.Water at the base, not overhead, and do it in the morning so foliage dries fast
Stunted, yellowing plants with roots that look brownish and waterlogged when you pull one up
Likely Causes
- Pythium or Phytophthora root rot — both triggered by consistently wet, poorly drained soil
- Heavy clay soil holding water around the crown after spring rains
What to Do
- 1.Pull affected plants out — there's no saving a root-rotted stock
- 2.Amend the bed with 2-3 inches of coarse compost or grit before replanting, or build up a raised row
- 3.Don't replant Matthiola in the same spot for at least one season
Tiny, scattered holes in young leaves, like someone went at them with a pin
Likely Causes
- Flea beetles (Phyllotreta species) — they hit brassica-family plants hard, and stock (Matthiola incana) is in that family
- Pressure peaks on new transplants during warm, dry April and May weather
What to Do
- 1.Cover transplants with row cover (Agribon AG-19 or similar) for the first 3-4 weeks after setting out
- 2.Sprinkle diatomaceous earth around the base of plants — reapply after every rain
- 3.Established plants usually outgrow minor flea beetle damage without intervention
Frequently Asked Questions
How long do Iron Marine stock flowers last in a vase?▼
Is Iron Marine stock easy to grow for beginners?▼
Can you grow Iron Marine stock in containers?▼
What do Iron Marine stock flowers taste like?▼
When should I plant Iron Marine stock seeds?▼
Will Iron Marine stock produce multiple flowers if I pinch it?▼
Growing Guides from Wind River Greens
Where to Buy Seeds
Sources & References
External authority sources used in compiling this guide.
- BreederJohnny's Selected Seeds
See the Methodology page for how this data is sourced, what's AI-assisted, and known limitations.