Heirloom

Iron Pastel Mix

Matthiola incana

Photo: Dale Cruse - 10M views from San Francisco, CA, USA · Wikimedia Commons · (CC BY 4.0)

Our soft pastel blend is reminiscent of pastel-colored candies and marshmallows. 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" blooms. 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

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Start Indoors

Transplant

Direct Sow

Start Indoors

Transplant

Direct Sow

Showing dates for Iron Pastel Mix in USDA Zone 7

All Zone 7 flower →

Zone Map

Click a state to update dates

Iron Pastel Mix · Zones 6–10

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

SeasonWarm season annual

FlavorPeppery, clove-like flavor with a spicy, aromatic quality.

ColorPastel multi-color blend

Size1 1/2-2"

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
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	—
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	—

Succession Planting

Iron Pastel Mix stocks produce one main flush of blooms — once a stem is cut and the plant has flowered out, you won't get a second wave the way you would from basil or lettuce. Start seeds indoors every 3–4 weeks from February through March (zone 7), then shift to direct sowing again around mid-August for a fall cut. Stocks go off in sustained heat above 80°F, so there's a real gap through the hottest weeks of summer where they simply won't perform, and you're better off not trying to force it.

Time that late sowing so plants hit their 90–105 day mark before your first frost date. In zone 7, a mid-August direct sow is about the last practical window for fall flowers.

Complete Growing Guide

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 Pastel Mix 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

For fresh Iron Pastel Mix stock flowers, store stems upright in a vase with cool water (65-72°F) in a cool location away from direct sunlight and ripening fruit. These blooms last 10-14 days in the vase. For preservation, air-dry by hanging bundles upside-down in a cool, dark, well-ventilated space for 2-3 weeks, creating long-lasting dried arrangements. Alternatively, press individual florets between book pages for 1-2 weeks to preserve them for crafts or culinary garnishes. For maximum longevity, freeze fresh flowers in ice cube trays with water, then store in freezer bags for several months—ideal for cocktail applications.

History & Origin

Iron Pastel Mix 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

+Soft pastel colors resemble attractive candy and marshmallow tones
+Strong, rigid stems ideal for professional cut flower arrangements
+Highly uniform series allows efficient one-cut harvest timing
+Early flowering within 90-105 days makes scheduling predictable
+Tightly spaced florets create compact, full-looking 1.5-2 inch blooms

Considerations

-Produces only one flowering stem per plant, limiting yield
-Cannot be pinched without terminating the single stem's flowering
-Slightly later to flower than comparable Katz variety
-Shorter and thicker stems than Katz may limit design versatility

Companion Plants

Marigolds and alyssum pull the most weight here. French marigolds (Tagetes patula) deter aphids and thrips through scent, and alyssum draws in parasitic wasps and hoverflies that clean up soft-bodied pest pressure before it compounds. Zinnias and cosmos are good neighbors for a different reason — they feed at similar root depths and won't crowd Matthiola out for water or nutrients the way a deep-taproot plant would.

The three to skip: Black Walnut produces juglone, a compound that's flat-out toxic to many annuals, and stocks are sensitive enough that planting within the canopy drip line is a bad gamble. Eucalyptus drops allelopathic compounds in its leaf litter that suppress germination and early growth around it. Fennel exudes root chemicals that stunt most neighboring plants — it's a poor companion for almost anything in the cut flower bed, and Matthiola is no exception.

Plant Together

Marigolds

Repel nematodes and aphids while attracting beneficial insects

Alyssum

Attracts beneficial insects like lacewings and provides ground cover

Nasturtiums

Act as trap crop for aphids and cucumber beetles

Zinnias

Attract pollinators and beneficial predatory insects

Cosmos

Attract beneficial insects and provide structural support

Lavender

Repels moths, fleas, and mosquitoes with aromatic oils

Petunias

Repel aphids, tomato hornworms, and squash bugs

Sunflowers

Provide beneficial habitat and attract pollinators

Keep Apart

Black Walnut

Produces juglone toxin that inhibits growth of many plants

Eucalyptus

Releases allelopathic compounds that suppress nearby plant growth

Fennel

Inhibits growth of most garden plants through allelopathy

Troubleshooting Iron Pastel Mix

What you'll see, why it happens, and what to do about it.

Gray, powdery coating on leaves and stems, usually showing up after plants have been growing 6+ weeks

Likely Causes

Powdery mildew (Erysiphe cichoracearum) — common on Matthiola in warm, humid conditions with poor airflow
Crowded spacing that traps moisture around the foliage

What to Do

1.Thin plants to at least 12 inches apart if you haven't already
2.Spray with a diluted neem oil solution (2 tbsp per gallon of water) every 7 days until symptoms stop spreading
3.Water at the base only — overhead watering on a warm afternoon is basically an invitation for this

Seedlings or young transplants collapsing at the soil line, stems look pinched or water-soaked

Likely Causes

Damping off — usually Pythium or Rhizoctonia fungi, both triggered by cold, waterlogged soil
Overwatering in the first 2–3 weeks after germination

What to Do

1.Pull and discard affected seedlings immediately — they won't recover
2.Let the top inch of soil dry out between waterings going forward
3.If starting indoors, use a sterile seed-starting mix and a tray with drainage holes, not garden soil

Leaves showing small, irregular holes or ragged edges, especially on young growth

Likely Causes

Flea beetles (Phyllotreta spp.) — tiny black beetles that jump when disturbed, very common on brassica-family plants like Matthiola
Cabbage loopers (Trichoplusia ni) if the damage is more scalloped and you spot frass

What to Do

1.Cover seedlings with row cover (Agribon AG-19 or similar) right after transplanting and leave it on until plants are 8–10 inches tall
2.For loopers, hand-pick in the evening or apply Bt (Bacillus thuringiensis) per label — it's safe and effective on caterpillars
3.Flea beetle pressure usually drops once plants size up past the seedling stage, so light damage on a 10-inch plant isn't worth losing sleep over

Frequently Asked Questions

How long do Iron Pastel Mix flowers last in a vase?▼

Iron Pastel Mix stock flowers typically last 10-14 days in a vase when kept in cool water (65-72°F), away from direct sunlight and ripening fruit. Change water every 2-3 days and re-cut stems at an angle to maximize vase life. Their sturdy, rigid stems make them excellent for long-lasting floral arrangements.

Can I grow Iron Pastel Mix stock flowers in containers?▼

Yes, Iron Pastel Mix performs well in containers. Use large pots (at least 8-10 inches deep) with well-draining soil. Ensure containers receive 4-6+ hours of sunlight daily. One flowering stem produces per plant, so space containers appropriately and avoid pinching, as it will stop the plant from flowering.

When should I plant Iron Pastel Mix seeds?▼

Sow Iron Pastel Mix seeds in spring (after last frost) for early summer blooms or in late summer for fall flowers. These varieties thrive in spring, early summer, and fall seasons. Direct sow or start indoors 6-8 weeks before your last frost date. They take 90-105 days from sowing to harvest.

What does Iron Pastel Mix taste like when used as edible flowers?▼

Iron Pastel Mix flowers have a peppery, clove-like flavor profile with a slightly spicy kick. This distinctive taste makes them ideal for garnishing salads, desserts, and cocktails. The flavor complements sweet applications particularly well, creating an interesting sweet-spicy contrast.

Is Iron Pastel Mix good for beginner gardeners?▼

Yes, Iron Pastel Mix is excellent for beginners due to its 'Easy' difficulty rating. These heirloom flowers are low-maintenance, perform well across multiple seasons, and produce strong, straight stems without requiring pinching or complex care. They're reliable and rewarding for first-time growers.

How does Iron Pastel Mix compare to Katz stock flowers?▼

Iron Pastel Mix is slightly later to flower than Katz but produces somewhat shorter and thicker stems. Both are high-quality stock varieties, but Iron offers a more compact, uniform series ideal for one-cut harvests. Iron's tightly spaced florets create 1.5-2" blooms compared to Katz's characteristics.