How to Plant, Grow, and Care for Stock Flowers

If you like fragrance in a garden, stocks should be on your list. They have a wonderful spicy scent with a hint of clove, and in the heat of summer will permeate a space with their beautiful fragrance.

Their distinctive aroma attracts many pollinators, so the whole atmosphere around the plants is one of fragrantly-colored spikes buzzing with bees and butterflies.

In this article, we will go through the steps to growing stocks successfully: sowing the seed, maintenance, cutting them for the vase, or just enjoying them in the garden.

What is It?

Stock flowers, or stocks, are pretty annuals. Matthiola incana are members of the Brassica family, Brassicaceae, which includes edible plants like cabbages, broccoli, Brussels sprouts, kale, and mustards.

It’s not surprising, then, that the flowers, leaves, and seedpods are all edible. There are various other common names for these annuals, including Brompton stock, hoary stock, gillyflower, and common stock.

Native Area

This species is native from Spain to Greece, including France, Italy, Albania, and Yugoslavia and the islands of Sicily, Corsica, and Sardinia. It is considered an introduced species in many other parts of the world but prefers a temperate climate and biome.

Characteristics

In their natural environments, stocks are considered shrubs or, more accurately, subshrubs, but they are also available around the world as annuals or biennials. The main blooming season is from late spring to mid-summer.

They grow anywhere from 10-32 inches high. The flower stalks stand proudly above the narrow, oval leaves. The many dwarf varieties make excellent bedding plants, with the taller varieties sought after by florists for use in design.

Flowers can be single or double in colors that range from white, yellow, peach, pink, purple, and various hues from the palest pink to the most vibrant purple. They form spikes of blooms clustered together, and the petals are slightly frilly.

Planting

There are two ways of getting stocks into your garden: sow from seed or plant seedlings already grown for you by a nursery.

They prefer cooler conditions to grow like any plants in the brassica family and, if planted out too late, may have stunted growth.

Growing from Seed

Start sowing in January or any time before March to take advantage of the cooler growing conditions.

Sow Indoors

• Fill your trays or pots with a seedling or germination mix that has been dampened with water.
• Spread the seeds over the top of the soil and pat down to secure the seeds to the soil. Don’t bury the seeds too deep. They need light to germinate. Keep well-watered while the seeds germinate, and keep the temperature consistent at around 60-65°F (16-18°C).
• After 10-14 days, the seeds should have germinated, and they can be pricked out and planted into individual pots or biodegradable pots to grow on.
• Once the seeds have their true leaves and have reached a size of around three to four inches, start the hardening-off process by taking the pots outside from around the beginning of March to get them acclimated to the outdoor conditions. Start by taking the seedlings outside for an hour and then increase this daily. Avoid hardening off in freezing weather. The temperature should be around 32°F (0°C) before you begin. Once you can see that they are a bit tougher, they can be planted out in the garden or in containers.

Direct Sow

• Prepare the soil by loosening it and raking and removing any stones or large clumps of soil. The soil should be fine and level.
• Sow the seeds as evenly as possible and press the soil down.
• Water well with a fine spray.
• Once the seeds have several leaves and reach three to four inches high, thin them out so that the stronger seedlings are at least 10 inches apart.

Transplanting

Transplant seedlings out around mid-March, depending on your climate. If it’s a bit cold, still cover them with hoops and a bit of frost cover, making sure to open up the cover if it’s not freezing. Once the temperature is about 32°F (0°C), they should be good to go.

How to Grow

Stocks are very hardy and tolerate all but the harshest frosty conditions. They can withstand the cold through winter until they burst into bloom in the spring. However, they do need some care and the right conditions to perform at their best.

Light

In most instances, they will prefer full sun, but if your summers are very hot, they will do better in partial shade with morning sun and afternoon shade. They will need at least 4 hours of sun to produce good blooms.

Water

Keep the soil evenly moist. A good top dressing of mulch will help keep the plants cool. If you notice the top two inches of soil is dry, apply irrigation.

Soil

Stocks like rich soil filled with good organic compost when planting. Turn the soil over to about eight to ten inches deep and add in plenty of compost, a few handfuls of slow-release general fertilizer, or Bio-tone Starter Plus Plant Food at a rate of four pounds per 100 square feet.

The pH of the soil should be neutral or more towards the alkaline side of the scale (6.5 – 7.5).

Temperature

Stocks prefer growing in cooler climates like all brassicas. In very hot summers, they will wilt. Their ideal temperatures stay below 65°F (18°C). They are considered frost-hardy except for severe frost.

Fertilizing

You can use a product like Garden-tone Organic Plant Food that is used primarily on vegetables like the brassicas we spoke of earlier on your stocks. Feed monthly at the recommended rate from May through to August. Don’t overfeed stocks, or they can develop root rot.

Maintenance

To encourage bushier plants with more flower spikes, pinch out the growing tips in spring and deadhead the spent flowers regularly. Cut off the flower spikes as close to the base as possible, and more will follow all through the season.

Propagation

The best way to grow stock is by sowing seeds or planting seedlings. At the end of the flowering season, leave one or two stems of flowers to go to seed so that you can collect them for the next season.

Long, narrow seed capsules will form along the stem and will turn from green to brown to indicate that they are ready for harvesting. Lay them out on paper in a warm spot. When the capsules split open, collect, label, and store the seed.

Collected seeds like this may not produce the same flower color as the original plant due to the chance of cross-pollination, so it’s a bit of a potluck when sowing – quite exciting, really, to see how they turn out.

Popular Varieties

‘Katz’

‘Katz’ is grown for its tall stems, 10-32 inches long, that are perfect cut flowers. They are known for their uniformity and are more heat tolerant than other varieties.

‘Cinderella’

‘Cinderella’ is a dwarf variety that has lovely double blooms on stems eight to ten inches tall. This is a popular variety for a long flowering season and pretty in borders or pots. This variety has received the Royal Horticultural Society’s Award of Garden Merit.

‘Vintage’

‘Vintage’ is a compact variety, 15-20 inches high in colors that range from white to pink, purple, and red. They are early flowering in the season.

‘Legacy’

‘Legacy’ stocks grow up to two feet tall in a variety of gorgeous colors.

Common Problems

There are not many problems with stocks, especially since the new hybrids are bred to be more pest- and disease-tolerant. Most problems will come from overwatering, soil that doesn’t drain well, or overcrowding.

Pests

When plants are stressed or have been exposed to excessive heat, pests are more likely to strike. Sucking insects like aphids, spider mites, and whiteflies can attack as well as flea beetles.

Some infestations can be controlled by cutting the infected parts away. In major infestations, use a pesticide for the control of the specific pest. Use with caution, as most pesticides are also harmful to beneficial insects and pollinators.

Make sure not to use the flowers for decorating salads and cakes with any plant that has had a chemical intervention.

Diseases

With overwatering and overcrowding come problems with diseases like mildew, grey mold, leaf spot, fusarium wilt, verticillium wilt, and root rot. Make sure there is enough air between plants, and that they are well-spaced apart.

Water at ground level in the morning so the water has time to evaporate during the day and is not sitting on the leaves.

Frequently Asked Questions