Column Stock

A fragrant cool-season cut flower with a single, unbranched spike densely packed with double flowers in soft pastels of purple, pink, cream, and white. Column stocks are prized by florists for their intense clove-like fragrance that fills a room. They prefer cool growing conditions and will bolt quickly in heat, so plant early for best results.

Start seeds indoors eight to ten weeks before the last frost date. Surface sow on moist seed-starting mix, pressing lightly but not covering. Maintain cool temperatures of 60 to 65 degrees Fahrenheit for germination in seven to fourteen days. For the highest percentage of double flowers, chill seedlings at 50 degrees Fahrenheit for seven to ten days at the cotyledon stage, then discard seedlings with dark green cotyledons, keeping only the lighter yellow-green ones which tend to produce doubles.

Start column stock seeds indoors eight to ten weeks before the last frost date for spring production. Sow seeds on the surface of moist seed-starting mix, pressing them lightly into the surface but not covering, as they need light to germinate. Maintain temperatures of 60 to 65 degrees Fahrenheit for germination in seven to fourteen days. Column stocks need cool growing conditions throughout their life cycle.

Transplant outdoors four to six weeks before the last frost, spacing six to eight inches apart in full sun with rich, well-drained soil. Column stocks are half-hardy and tolerate light frost, performing best in the cool conditions of spring and autumn. They produce a single, unbranched spike densely packed with double flowers in exquisite shades of purple, pink, cream, white, and lavender.

Water at the base to avoid wetting the dense foliage and flower spike, which promotes botrytis. Feed with a balanced liquid fertilizer every two weeks. Column stocks bolt quickly in hot weather, so time plantings to mature during cool periods. In mild climates, autumn plantings provide winter and early spring flowers. The intense clove-like fragrance is one of the most powerful and delightful of any cut flower.

Column stocks are classic companions for other cool-season cut flowers including snapdragons, larkspur, ranunculus, and sweet peas. Plant in blocks of single colors in cutting gardens for impactful harvest. In borders, the intense fragrance makes stocks ideal near pathways, patios, and windows where the scent can be enjoyed. Pair with spring bulbs like tulips and daffodils for a complete cool-season flower display.

Column stocks thrive in rich, well-drained, slightly alkaline soil with a pH of 6.5 to 7.5. The higher pH helps prevent clubroot, a devastating disease of the brassica family to which stocks belong. Amend the planting area with compost and lime if the soil is acidic. Feed every two weeks with a balanced liquid fertilizer during active growth. Stocks are moderate feeders and respond well to consistent nutrition without heavy fertilization.

Ideal Temperature

Hardiness Zone Compatibility

Cut column stock stems when about half the florets on the spike have opened. Cut in the cool of morning and place immediately in cool water with floral preservative. The intense clove fragrance fills a room from even a few stems. Strip lower foliage and change water every two days. Cut column stocks last five to ten days in a vase. The single, unbranched form makes them ideal for formal arrangements where clean, vertical lines are desired.

Storage & Preservation

Column stocks are cool-season annuals that cannot be stored over winter. Seeds can be saved from plants that produce single flowers, which set seed more readily than the desirable doubles. Store seeds in paper envelopes in a cool, dry location. A special selectable seedling trait allows experienced growers to identify double-flowered seedlings at the cotyledon stage: in cold conditions, seedlings with lighter-colored cotyledons tend to produce double flowers.

Troubleshooting Common Problems

The most common issue is premature bolting in hot weather, as stocks are strictly cool-season plants that flower poorly in heat. Time plantings to mature during cool periods for best results. Clubroot is a serious concern since stocks are members of the brassica family. Never plant where other crucifers have been grown recently. The desirable double flowers are sterile and do not set seed, so seed must be saved from the less ornamental single-flowered plants.

Growing Tips

1. Sow seeds on the surface of moist seed-starting mix and press gently without covering, as Matthiola incana seeds need light exposure to germinate reliably.
2. Maintain germination temperatures between 15-18°C (60-65°F) and avoid exceeding 20°C, as high temperatures significantly reduce germination rates in stock seeds.
3. To select for double flowers, chill seedlings at 5-8°C for 3-4 days at the cotyledon stage and remove darker green seedlings, which are more likely to produce single flowers.
4. Transplant seedlings when they have 4-6 true leaves, handling them carefully by the leaves rather than the stems to avoid damaging the single growing point that forms the flower spike.
5. Provide full sun in cool climates but partial afternoon shade in regions where temperatures regularly exceed 24°C to prevent premature bolting and poor flower quality.
6. Amend soil with lime if your garden soil is acidic, as column stock strongly prefers a slightly alkaline pH between 6.5 and 7.5, reflecting its natural limestone cliff habitat.
7. Water at the base of plants rather than overhead to prevent botrytis and other fungal diseases, which readily attack the dense flower spikes in humid conditions.
8. Apply a potassium-rich liquid fertilizer every 10-14 days once flower buds become visible to enhance color intensity and improve the structural strength of the flower spike.
9. Stake individual plants with thin bamboo canes in exposed or windy locations, as the heavy flower spike can cause the single stem to bend or snap during storms.
10. For the longest vase life, harvest flower spikes early in the morning when the bottom quarter to third of florets have opened, and immediately place stems in cool water with floral preservative.