Stock 'Iron White'

Iron White (Matthiola incana)

Also known as Stock or Gillyflower

Iron White stands like a pillar of purity in the garden — snow-bright blooms arranged along sturdy, straight stems, each floret crisp and luminous. The tightly layered flowers, 1½–2" across, form a pristine, compact spike, giving an impression of abundance and quiet elegance.

A florist’s favourite for its reliability and premium quality, this column-type stock produces one glorious cut per plant. Flowers may be single or double; with careful seedling selection, doubles can be achieved in nearly every stem.

Petals carry a delicate peppery, clove-like note, making them a charming edible garnish for salads, desserts, and chilled drinks. Pair with soft pastels, pale blues, or feathery greenery for arrangements that breathe freshness and grace. Best in full sun and well-drained soil, and should be left unpinched to ensure its single, perfect bloom.

DETAILS:

QTY: 50

TYPE: Annual

SITE: Full Sun

DEPTH: 1/4"

GERMINATION: 7-14 days at 18-24°C

HEIGHT: 24-28”

MATURITY: 90-105 days

SPACING: 4-6" Trellis, such as Hortonova, used as horizontal support, is necessary when the temperatures are consistently above 16°C or where it rains frequently.

PINCH: No

Transplant (recommended): Stock is a cool-weather crop, so starting transplants indoors is the best way to get ahead of the heat. Sow seeds 5–6 weeks before you plan to move them to a field or a protected structure. For a continuous harvest of flowers, make successive plantings every two weeks. The optimal times for growing are for spring and fall blooms.

Direct Seeding (alternative): Sow seeds directly outdoors after all danger of frost has passed. This method may result in a later bloom time compared to starting indoors.

Selecting for Double Flowers

While a difficult and time-consuming process, you can select for double-flowering plants by observing visual differences in the seedlings. After the seedlings have emerged and are in the cotyledon stage, expose them to chilling temperatures of 4-7°C for 3-4 days.

After chilling, you can identify the types of flowers the plants will produce:

• Select lighter green seedlings with an oval-shaped cotyledon; these will produce the desired double flowers.

• Seedlings with a darker green color and rounder cotyledons will produce single flowers.

Pinching: Do not pinch stock plants. Pinching can negatively affect the development of their single, central flower spike, which is the primary source of their classic bloom.

Pest Prevention: As a member of the brassica family, stock is a favorite food for flea beetles. To protect young plants from damage, cover them with a floating row cover immediately after transplanting them into the garden.

Soil Preference and Watering: Stock thrives in full sun and requires well-drained, fertile soil. Keep the soil consistently moist but never soggy. Once plants are established, water deeply but infrequently.

Fertilizing: To encourage strong growth and beautiful blooms, fertilize with a balanced liquid fertilizer every 2–4 weeks. A layer of compost applied at planting time can also provide a good nutrient base.