Heirloom

Katz White

Matthiola incana

Photo: Ввласенко · Wikimedia Commons · (CC BY-SA 3.0)

Long stems with 1 1/2-2", pure white blooms. Early blooming one-cut series. Performed well in our spring, early summer, and fall trials. Good uniformity in bloom time and stem length. 55-60% double-flowering without selection; some selection possible. 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

90-100d

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 Katz White in USDA Zone 7

All Zone 7 flower →

Zone Map

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Katz White · Zones 6–10

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

SeasonWarm season annual

FlavorPeppery, clove-like flavor with subtle spice notes.

ColorPure white

Size1 1/2-2"

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 is a one-flush crop — each plant sends up its spike, you cut it, and that's largely the end of it. Succession planting is worth doing if you want continuous cuts across a few weeks. Indoors, sow every 3 weeks from early February through mid-March (zone 7) for a spring run. Don't push past a mid-March sow for spring; anything started later won't finish before heat shuts it down. For a fall run, start a second round indoors in late August and transplant out in early October once nighttime temps drop back into the 50s°F.

The 80°F daytime threshold is the hard limit. Above it, stem length drops, flowers blast open within a day of cutting, and fragrance goes flat. Plan your sow dates backward from your last reliably cool week, not forward from your first warm one.

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

Katz White reaches harvest at 90 - 100 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

Katz White flowers are best stored in a cool environment to extend vase life. Keep cut stems in a tall vase filled with fresh, cool water (65-72°F) on a countertop away from direct heat, sunlight, and ripening fruit. Change water every 2-3 days and recut stems to maintain freshness; blooms typically last 7-10 days. For preservation: (1) Air drying—bundle stems loosely and hang upside down in a dark, well-ventilated space for 1-2 weeks, ideal for long-term storage; (2) Pressing—place individual petals between parchment paper under heavy weights for decorative use in crafts and pressed flower arrangements; (3) Edible preservation—crystallize petals with egg white and sugar for garnishing desserts, storing in an airtight container for several weeks.

History & Origin

Katz White 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

+Pure white blooms with long stems ideal for cut flower arrangements
+Early blooming one-cut series performs reliably across spring, summer, and fall
+Excellent uniformity in bloom time and stem length requires minimal sorting
+55-60% naturally double flowers without requiring labor-intensive selection
+Edible peppery-clove flavored petals add unique gourmet garnish appeal

Considerations

-Single flowering stem per plant limits yield compared to pinchable varieties
-90-100 day maturity requires extended growing season before harvest
-Pinching terminates flowering so traditional branching techniques are impossible
-One-cut nature means entire plant investment yields only one stem

Companion Plants

Marigolds, nasturtiums, and sweet alyssum are the companions worth prioritizing. Tagetes patula specifically releases thiophenes from its roots — compounds that suppress soil nematodes and deter aphids and whiteflies, the soft-bodied insects most likely to cruise Matthiola. Nasturtiums pull double duty as a trap crop: aphids tend to pile onto them first, which keeps stock spikes cleaner during peak pressure. Sweet alyssum draws parasitic wasps (Braconidae and Chalcidoidea families) that target cabbage loopers — the same caterpillars that treat Brassicaceae flowers like a buffet. Lavender and catmint add pollinator traffic without fighting for resources, since both run shallow roots and tolerate drier conditions than stock does.

Black walnut is the one to keep well off the premises. Juglone, the compound Juglans nigra leaches through its roots and decomposing hulls, is toxic to a wide range of Brassicaceae plants, and Matthiola sits squarely in that family. Eucalyptus is a slower problem — its allelopathic oils accumulate in the soil over time and suppress root development in nearby plants. Sunflowers aren't toxic, but at 5–8 feet they'll shade stock out entirely, and they're heavy feeders that pull nitrogen fast from shared beds.

Plant Together

Marigolds

Repel nematodes, aphids, and whiteflies while attracting beneficial insects

Nasturtiums

Act as trap crops for aphids and cucumber beetles, attract pollinators

Sweet Alyssum

Attracts beneficial predatory insects like lacewings and parasitic wasps

Zinnia

Attracts butterflies and beneficial insects, provides continuous bloom companion

Catmint

Repels ants, aphids, and rodents while attracting pollinators

Cosmos

Attracts beneficial insects and provides structural support without competition

Chives

Natural pest deterrent against aphids and thrips

Lavender

Repels moths, fleas, and mosquitoes while attracting bees and butterflies

Keep Apart

Black Walnut

Produces juglone toxin that inhibits growth and can kill sensitive plants

Eucalyptus

Releases allelopathic compounds that suppress growth of nearby plants

Sunflowers

Can be allelopathic and compete aggressively for nutrients and water

Troubleshooting Katz White

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

Seedlings collapse at soil level, stem pinched and dark at the base

Likely Causes

Damping off (Pythium or Rhizoctonia spp.) — triggered by overwatering, poor drainage, or overcrowded trays
Starting mix that stays wet too long between waterings

What to Do

1.Thin seedlings to at least 1 inch apart in the tray as soon as they germinate
2.Water from the bottom and let the top inch of mix dry out between waterings
3.Use a sterile, well-draining seed-starting mix — not garden soil or old bagged mix that's been sitting open

Lower leaves yellowing and dropping, with a faint gray-white powder on stems or remaining leaves

Likely Causes

Powdery mildew (Erysiphe cruciferarum) — common on Matthiola in humid, low-airflow conditions
Planting too close together, blocking airflow between stems

What to Do

1.Strip affected leaves and bin them — don't compost
2.Space plants at least 12 inches apart; stock wants air moving through it
3.A diluted neem oil spray (2 tsp per gallon) applied early morning can slow spread if caught quickly

Buds form but flowers fail to open, or spikes stall out at 6–8 inches and stop elongating

Likely Causes

Heat stress — Matthiola incana stops performing reliably once daytime highs push past 80°F
Planting too late in spring, leaving no runway before summer heat sets in

What to Do

1.In zones 7–10, transplant outdoors no later than late April so plants can finish before June heat
2.If spikes have stalled, cut them at the base — those stems won't recover once they've been baked
3.For fall cuts, start seeds indoors in late August and transplant in October when temps drop back below 75°F

Ragged holes chewed in leaves overnight, especially on young transplants

Likely Causes

Cabbage loopers (Trichoplusia ni) or imported cabbageworm (Pieris rapae) — Matthiola is in the Brassicaceae family, so it draws the same caterpillars as kale or broccoli
Slugs — especially in cool, wet springs

What to Do

1.Check the undersides of leaves for pale green caterpillars; hand-pick and drop in soapy water
2.Apply Bacillus thuringiensis (Bt) as a foliar spray if caterpillar pressure is heavy — it won't hurt pollinators
3.For slugs, scatter iron phosphate bait (Sluggo) around the base of plants after transplanting

Frequently Asked Questions

How long do Katz White carnation flowers last in a vase?▼

Katz White blooms typically last 7-10 days in a vase with proper care. To maximize longevity, use fresh, cool water, change the water every 2-3 days, and recut the stem ends on a diagonal. Keep the vase away from direct sunlight, heat sources, and ripening fruit, which produce ethylene gas that shortens flower life.

Can you grow Katz White carnations in containers?▼

Yes, Katz White carnations grow well in containers, making them ideal for patios and balconies. Use well-draining potting soil and a pot with drainage holes, at least 6-8 inches deep. Ensure they receive 4-6+ hours of sunlight daily. Container plants may need more frequent watering than in-ground plants, especially during hot weather.

What do Katz White carnation flowers taste like?▼

Katz White carnation flowers have a peppery, clove-like flavor with subtle spice notes. This distinctive taste makes them excellent edible garnishes for salads, desserts, and cocktails. The flavor is more pronounced in the petal bases, so remove the bitter white base before consuming. Always use pesticide-free flowers grown specifically for culinary purposes.

When should I plant Katz White carnations?▼

Sow Katz White carnations indoors 6-8 weeks before your last spring frost, or direct sow outdoors after frost danger passes. These early-blooming flowers perform well in spring, early summer, and fall. They're sensitive to extreme heat, so in hot climates, plan for fall and spring plantings to avoid mid-summer stress.

Is Katz White a good carnation variety for beginners?▼

Absolutely. Katz White is classified as 'Easy' difficulty and is an excellent choice for beginners. It performs reliably in various growing conditions and produces consistent bloom times and stem lengths. The main consideration is avoiding pinching, as this variety produces only one flowering stem per plant, and pinching will terminate flowering entirely.

Why shouldn't you pinch Katz White carnation plants?▼

Unlike many other carnation varieties, Katz White produces only one flowering stem per plant. Pinching (removing the growing tip to encourage branching) will terminate flowering rather than create multiple stems. Let the single stem grow uninterrupted for optimal bloom production and stem length.