Crucial Tips for Growing Stock Flowers (Matthiola Incana) from Seed to Bloom

If you’ve ever seen and smelled Matthiola incana or Hoary Stock flowers, you’ll understand why they are so popular. These highly fragrant flowers are gorgeous in spring and early summer bouquets. They have a sweet, spicy scent similar to cloves. You will want to plant these flowers where you can enjoy their fragrance in the garden.

Stock is a member of the Brassica family, like broccoli, Brussels sprouts, and kale. However, instead of producing healthy green leaves, this plant produces tall stalks of flowers. The leaves are fuzzy or “hoary,” giving it its name. The flowers are edible and have a floral taste.

Stock blooms in a range of pastel colors from white, pink, and purple. The flowers can be single or double petals. Usually, with a seed mix, you will have about 50% single bloom and 50% double bloom.

The sweet, spicy scent and full blooms make Matthiola incana or stock an excellent filler flower. There are a few crucial tips that you need to know for successfully growing stock flowers.

The most important thing to know about stock is that it is a cool-weather flower. Like other plants in the Brassica family, it will grow and bloom best when temperatures are moderate. Night time temperatures below 60ºF is when the plants will produce the most blooms. Stock can even handle a frost or two, but warm temperatures are a signal to stop growing. 

Stock will stop flowering when temperatures get too hot, so in most locations, stock is grown as a spring flower, but it can also be grown in the fall when the temperatures are moderate. Timing is crucial to get stock plants out in the garden at the right time. Seeds are started indoors, and seedlings are transplanted after the danger of frost has passed in the spring or temperatures are cool enough in the fall.

• Stock seeds need light to germinate. Lightly cover the seeds with soil or just press them into the growing medium.
• Seeds need to stay moist to germinate. Start with a moist seed starting mix.
• Use a humidity dome to keep the seeds moist but not waterlogged. Use a spray bottle to mist the seeds if needed.
• Temperatures between 60-70ºF are best for germination.
• Stock seeds should sprout in 10 to 14 days.

You want to take advantage of the cool weather to get stock flowers to grow and bloom. In many locations, such as here in the Midwest, March is a great time to plant them out. You can cover the plants with a frost cover at night when needed.

Once the stock seedlings have true leaves and are several inches high, they can be hardened off for transplanting outdoors. If temperatures are above 32ºF during the day, you can start placing them outside in the sunshine. Start with an hour and increase the time each day.

A hoop house is an excellent place to plant stock flowers in spring. It will protect them from the winds and rain. You can also use frost cloths and row covers to protect them from freezing temperatures and heavy rain.

Space stock plants 8 to 10 inches apart. For tall varieties, you will want to have flower netting or supports in place to protect them from strong winds. Dwarf varieties are less susceptible to blowing over.

Once you understand the temperature needs and growing conditions of stock flowers, you’ll have greater success with beautiful, fragrant blooms.

Stock flowers grow best in full sun to partial shade. Morning sun with afternoon shade is ideal.

Plant stock in well-draining, fertile soil. They don’t do well in acidic soil, so test the pH and maintain a neutral to slightly alkaline soil (6.5 to 7.5).

Stock does not have an extensive root system, so keeping it well-watered and weed-free is important. Keep soil consistently moist but not soggy.

While stock plants like to grow in nutrient-rich soil, too much fertilizer can result in root rot. It is better to amend the soil and add compost before planting.

Flower farmers may want to stake the flowers so they don’t blow over and bend as they grow. Also, consider growing stock flowers in a hoop house where they are protected from the weather. Shade cloth can also help produce more flowers when days get longer and temperatures rise.

Stock flowers are considered “one and done.” They grow, bloom, and then are finished.

If you are growing stock plants and aren’t cutting them for flower arranging, you can remove spent blooms and trim them back as needed when the flower stalks die off.

When harvesting flower stalks for floral arrangements, cut stalks when 1/2 to 1/3 of the florets are open.

Stock flowers are used in floral arrangements for their tall blooms and sturdy stems. Typical vase life is 7 to 10 days.

Stock doesn’t have many problems with pests or diseases. The common annoyance of aphids and spider mites can be treated as needed.

Growing in well-draining soil and watering the roots while keeping the foliage dry can help avoid any root rot and fungus problems.

Stock is considered a biennial because it goes to seed in the second year. It is usually grown as an annual.

Stock can be grown in containers. Just make sure you grow it in a large enough container for its mature size. A dwarf variety, such as our heirloom Dwarf Mixed Hoary Stock, is a perfect choice for containers.

The time of year to grow stock flowers can depend on your climate and how you protect it. A hoop house is excellent for protecting the plant and letting you get it growing early in the spring. Seeds started indoors can be transplanted outside in the cooler fall weather.

One of the reasons to grow flowers is for their intoxicating fragrance. Stock flowers are incredibly fragrant and beautiful and are high on the list of desired flowers in arrangements. As a cool-weather flower, they are one of the first to bloom in spring. Plant this beautiful flower in your garden and enjoy its heady spring fragrance.