How to grow stock
Overview
Stock (Matthiola incana) is a cool-season annual grown for its intensely fragrant, often double flower spikes in shades of white, pink, purple, and cream. It is a classic cottage-garden plant that thrives in the mild weather of spring and autumn, providing reliable colour and scent in beds and borders.
Varieties
- Matthiola incana 'Giant Imperial' — A tall, double-flowered strain with strong stems, ideal for cutting in Australian gardens.
- Matthiola incana 'Mammoth' — A large-flowered, late-blooming variety with excellent fragrance, popular for cool-season beds.
- Matthiola incana 'Cinderella' — A compact, early-flowering dwarf stock suited to pots and borders.
- Matthiola incana 'Vintage' — A heat-tolerant mix with pastel shades, bred for longer performance in warmer zones.
Soil Preparation
Stock prefers a well-drained, loamy soil with a pH of 6.5–7.0. Before planting, enrich the bed with well-rotted compost or a balanced organic fertiliser. Ensure good drainage, as stock is prone to root rot in waterlogged conditions.
Growing Guide
Sow stock seed directly into well-drained, moderately fertile soil in a sunny position, or start in punnets for transplanting. Space plants 20–30 cm apart; for cut flowers, plant in rows 30 cm apart. Pinch out the growing tip of seedlings at 10 cm tall to encourage bushier growth and more flower spikes. In cool climates, start seed indoors in late winter for spring blooms; in temperate zones, sow in autumn for winter–spring flowering. Stock is sensitive to heat and will bolt if exposed to prolonged high temperatures, so time sowing for the cooler part of the year.
Sowing
Sow stock seed 3–5 mm deep, 15–20 cm apart, in rows or clusters. Germination takes 7–14 days at 15–20°C. Direct sowing is preferred, but transplanting is fine if done carefully when seedlings are 5–7 cm tall.
Care
Feed stock every 2–3 weeks with a balanced liquid fertiliser (e.g., 10-10-10) during active growth. Deadhead spent flowers regularly to prolong blooming and prevent early seeding. After the main flush, cut back leggy stems to encourage a second wave of flowers.
Companion Planting
Plant stock with snapdragons, pansies, and violas for a classic cool-season colour combination. Avoid placing near heavy feeders like sweet corn or tomatoes, which may compete for nutrients. Good companions also include calendula, dianthus, and lobelia.
Common Pests & Risks
Aphids and caterpillars are common on stock in Australian gardens. Control aphids with a strong water spray or insecticidal soap; treat caterpillars with Bacillus thuringiensis (Bt) or hand-pick. Downy mildew can occur in humid, poorly ventilated conditions; space plants well and avoid overhead watering.
Harvesting
Harvest stock flower spikes for cut flowers when the lowest 2–3 florets have opened and the buds above show colour. Cut stems early in the morning, and place immediately in water. For seed saving, allow a few plants to mature and dry; collect seed pods when they turn brown.
Troubleshooting
Yellowing lower leaves: overwatering or poor drainage; reduce watering and improve soil. Stunted growth with few flowers: too much heat or late planting; sow earlier in the season. Leggy, floppy stems: insufficient light or overcrowding; thin plants and ensure full sun. Brown leaf edges: salt buildup from fertiliser or dry soil; flush soil and water regularly. Powdery mildew on leaves: poor air circulation; space plants and avoid overhead watering.