Agrostemma
( ag - ros - STEM - uh )
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At-A-Glance InformationCommonly known as Corn Cockle, this genus includes annual flowering herbaceous plants that need full sun and moderate water to perform well in the garden. These plants are sometimes considered weeds, and are native to the Mediterranean. Several varieties are wonderful ornamental plants for gardens, and have a wispy and open habit with delicate blooms. Scentless flowers are 2-3 inches wide and sit atop 6-12 inch tall stems. They are ideal for cottage gardens and for growing in borders, and are often included in wildflower seed mixes. Take care when planting this flower in your yard, as all parts of the plant (especially the seeds) are toxic to humans and pets if ingested.
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Agrostemma Species and Varietals
The genus Agrostemma, which is in the plant family Caryophyllaceae, includes two species and is a close relative of Pink and Carnation. The generic name is derived from the Greek words agros (meaning field) and stemma (meaning garland or crown). Corn Cockle grows best in USDA hardiness zones 7-12 or Sunset growing zones 1-24. See the species descriptions below for more information. To find your zone, click here: Zone Map.
Agrostemma githago (Common Corncockle)
This species reaches up to 40 inches tall when mature and in bloom, and produces a single pink to purple flower per stem. Narrow leaves are pale green and oppositely arranged. Plants are native to Europe, but have naturalized all over the world and in some areas have been identified as invasive weeds. Ornamental garden cultivars are listed and described below:
This species reaches up to 40 inches tall when mature and in bloom, and produces a single pink to purple flower per stem. Narrow leaves are pale green and oppositely arranged. Plants are native to Europe, but have naturalized all over the world and in some areas have been identified as invasive weeds. Ornamental garden cultivars are listed and described below:
'Blossom Pearl'
With 1-2" blush-pink blooms atop long, graceful stems. |
'Milas'
Deep purplish to pink blossoms that are lined and spotted with deep purple. Center eye is white. |
'Ocean Pearl'
White flowers with black flecks. |
'Pink Contessa'
With light pink petals. |
'Purple Queen'
Deeper pinkish-purple blooms. |
'Sakuragai'
White with light pink lines. |
Caring for Agrostemma
Agrostemma is typically grown from seed, either direct-sown into the garden soil or started indoors and transplanted out after the last frost of the year. Start seeds indoors between 4 and 6 weeks before the last frost date. Plant your Agrostemma, or Corncockle, in a space in the landscape that receives full sun; ideally, they appreciate between 6 and 8 hours of sun each day for the best blooms. When these flowers are grown in less light, they will not flower as profusely. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 6.0 and 7.0 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these plants perform well in consistently moist soils. Increase waterings during extended periods of hot weather. Corn Cockle does not need to be pruned, though deadheading will extend the blooming period. Deadheading also prevents these flowers from re-seeding freely in the garden. No fertilizers needed. These annuals can be pulled and composted at the end of the year and re-sown in the garden the following spring.
Harvesting Agrostemma
Corn Cockle can be grown for its cut flowers, which add lightness and color to mixed arrangements. They take between 90 and 100 days from seed to harvest, and are cut in summertime. If growing Corn Cockle in a cut flower garden, it is recommended to succession sow to have a lengthier harvesting time. The best time to harvest Agrostemma flowers is in the morning, after dew has dried but before the heat of the day has set in. Using sharp, clean shears or snips, cut the flowering stem at its base and drop it into a bucket of cool water. They have a vase life of between 5 and 7 days.
Harvesting Agrostemma
Corn Cockle can be grown for its cut flowers, which add lightness and color to mixed arrangements. They take between 90 and 100 days from seed to harvest, and are cut in summertime. If growing Corn Cockle in a cut flower garden, it is recommended to succession sow to have a lengthier harvesting time. The best time to harvest Agrostemma flowers is in the morning, after dew has dried but before the heat of the day has set in. Using sharp, clean shears or snips, cut the flowering stem at its base and drop it into a bucket of cool water. They have a vase life of between 5 and 7 days.
Propagation
The best way to propagate Corn Cockle is through seed. To harvest seeds from your plant, allow flowers to stay on the plant and form seed pods, which should happen around early fall. Please keep in mind that the seeds of Corn Cockle are poisonous, so handle them with care, and ensure that children and pets will not come into contact with them. Release your seeds from the pods, and put them in a container so they are not misplaced. Then, gather your materials. You'll need a pot or seed tray, potting medium (ideally a rich, loamy soil, but it can be any type), and a spray bottle filled with water. Once you've gathered your materials, follow these instructions:
- About six to eight weeks before your area's last frost of springtime, prepare your pots or seed trays by filling them with soil and watering them to ensure good drainage is occurring. Then, set your seed(s) on top, spaced about 8 inches apart. Cover them with a quarter inch of soil, and spray the soil with your water bottle until it is moist.
- Place your pots or seed tray in an area that will receive bright, indirect light and stays at a temperature of between 55 to 65 degrees Fahrenheit. Continue to monitor your soil for moisture, spraying (and then once the seedlings are large enough, watering) the soil when it gets dry.
- When the last frost of your area has passed in the springtime, plant your seedlings in a sunny area of your garden and follow the care instructions above.
- Alternatively, Corn Cockle seeds can be direct-sown in the landscape after the last frost of the year has passed and soil temperatures have risen to at least 55 degrees Fahrenheit.
Corn Cockle seed pods ready to be harvested.
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Corn cockle seeds are tiny, brown, and have rough exteriors.
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Problems and Pests
Note that Corn Cockle is considered an invasive weed in some areas, including West Virginia, Virginia, and New Hampshire. Check with local authorities before planting. Corn Cockle plants can be susceptible to developing issues with the following pests and diseases in the landscape:
- Downy Mildew
- Aphids
- Thrips
- Whiteflies
- Powdery Mildew
Gallery
Corn Cockle is a great wildflower, but can also be grown in more formal gardens.
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Corn cockle flowers have dark lines.
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Agrostemma githago 'Ocean Pearl' planted amongst other flowers can make a great border for your yard.
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Videos
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All about caring for and growing Corn Cockle.
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How to direct-sow Corn Cockle in your garden.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 340, Agrostemma githago (Corn Cockle)
