How to Grow and Care for Cornflower (Bachelor Buttons)

Cornflower, also known as bachelor’s button, is a popular feature in many a garden because of its vivid, brilliant blue flowers – considered as one of the only true natural colors of blue in the botanical world.

This annual cornflower is a member of the Asteraceae, which is a widespread group of plants and includes the likes of daisies, asters, and sunflowers.

Admired for its crisp blue blooms, the cornflower draws the attention of butterflies and bees in droves, making it an ideal choice for pollinator gardens.

The striking blue cornflower, with its gray-green leaves and sturdy stems, is often lauded for looking beautiful both in a home garden and vase.

The tradition of men wearing a cornflower boutonniere for weddings further compounds its popularity. Florists adore it for being a versatile accent to various garden blossoms, which would otherwise be dominated by shades of pinks, reds, and yellows.

Cornflower plants thrive in full sun in well-drained soil, areas where poor soil conditions might discourage the growth of other plants. Garden centers are often filled with bedding plant varieties of cornflowers, making them accessible to gardeners of all experience levels.

What’s more, with a wider range of blossom colors now available, your garden can be a canvas for cornflower in hues of pink, white, and purple. In a vase, they blend well with Snapdragons, Sweet William, and Love-in-a-Mist (or Nigella).

As a master gardener, I’ve always loved growing cornflowers. In this article, I’ll share everything you need to know about growing and caring for these stunning blue flowers.

Botanical Name: Centaurea cyanus

Common Name: Cornflower, bachelor’s button

Family: Asteraceae

Plant Type: Annual

Hardiness Zones: 2 – 11 (USDA)

Sun Exposure: Full, partial sun

Soil Type: Moist, well-drained

Soil pH: Alkaline

Bloom Time: Spring, summer

Flower Color: Blue, purple, pink, white, red

Native Area: Europe

Cornflower Plant Care

Cornflowers, also known as bachelor’s buttons, feature crisp blue blooms and are a favorite of pollinators such as bees and butterflies.

For optimal growth, sow seeds in well-drained soil and full sun. Be sure to thin seedlings to prevent issues like rot and rust that can occur with not enough air circulation.

The plant is susceptible to garden pests like aphids, mealybugs, and leafhoppers, so it is essential to monitor regularly. Often used as a bedding plant, the gray-green leaves of the cornflower contrast beautifully with the brilliant blue flowers, making it a popular choice for home gardens and florists alike.

Such is its popularity that garden centers often stock a wider range of blossom colors. Remember to incorporate staking practices if stems become too tall or heavy.

Light

Cornflower craves full sun to develop its signature brilliant blue flowers. This plant needs a minimum of six hours of direct sunlight each day.

The more light these buds receive, the more they reward the gardener with abundant, crisp blue garden blossoms.

A sun-soaked location is essential for achieving the cornflower’s wider range of blossom colors.

Well-lit conditions also help prevent fungal diseases like rot and rust, which can occur when there’s not enough air circulation or light.

Soil

Cornflowers thrive best in well-drained soil. Too much moisture can lead to problems such as rot and rust, damaging the plant’s health.

The soil should also be rich in nutrients to promote full, healthy blooms. Despite their preference for nutritious soil, cornflowers are quite adaptable and can grow in poor soil conditions as well, though this might affect the vibrancy of their blooms.

If you find that your garden soil is heavy clay or quick-to-drain sandy soil, consider adding some compost to aid in water retention and fertility. The addition of organic matter also creates a loose soil structure, preventing issues related to not enough air reaching the cornflower’s roots.

Water

The cornflower is a drought-tolerant plant, appreciated for its crisp blue and brilliant blue flowers, cherished as the only true natural color of blue amongst the widespread group of plants.

These plants enjoy well-drained soil and are resilient even under low water availability. Regular but moderate watering is advisable so as not to create a soggy environment where rot can develop.

Overwatering is a common mistake by home garden owners with cornflowers because too much water can literally drown the plants, cutting off the air supply to the roots and creating a breeding ground for pests.

Never allow a cornflower plant to sit in water or remain overly wet for extended periods of time. Instead, allow the soil to somewhat dry out between watering, then soak thoroughly.

Temperature and Humidity

Cornflowers thrive in full sun and prefer a well-drained soil. These brilliant blue flowers as well as their close relatives in the compositae family, such as asters and daisies, adapt well to various climates but flourish best in temperatures ranging from 60°F to 75°F (15°C to 24°C).

Particularly, the annual cornflower, widely known for its crisp blue and gray-green colors, tolerates a wide range of temperatures and humidity levels. However, too much humidity or not enough air circulation can be detrimental, leading to problems like rot and rust.

To prevent such issues, thin seedlings to provide proper spacing and consider staking taller varieties for better air movement.

Fertilizer

Cornflowers thrive best in well-drained soil with moderate fertility. An excess of nutrients, particularly nitrogen, can lead to lush gray-green leaves but few blooms, depriving your garden of the brilliant blue flowers that give this plant its popularity.

A slow-release organic fertilizer or a balanced synthetic one (such as a 10-10-10) applied in early spring can provide the right nutrient boost.

Make sure not to over-fertilize, as this can make the plant more susceptible to pests. Remember to water the soil adequately after applying fertilizer to avoid root burn and promote nutrient absorption.

Pruning

Cornflower tolerates a mild pruning regimen well. As a master gardener, I suggest lightly snipping off spent blooms off the brilliant blue flowers, encouraging the plant to produce more buds.

Routine pruning also helps keep these crisp blue garden blossoms looking tidy and healthy. Occasionally, stems may benefit from staking if they become too long and laden with blooms.

However, be mindful not to over-prune, as cornflowers need a good amount of foliage to maintain robust health.

Types of Cornflower

Blue Boy

Beloved by florists and home gardeners alike for its brilliant blue flowers, the Blue Boy is a popular variant of the annual cornflower. As the name suggests, it features crisp blue petals. This type loves full sun and well-drained soil, making it a welcome addition to any garden that ticks these boxes.

Tall Double Mixed

Tall Double Mixed cornflowers are known for their wider range of blossom colors, boasting shades varying from deep maroon to bright white.

This variety is likely to be found at garden centers, given their growing popularity. They’re also a precious resource for pollinators like bees and butterflies due to their abundant blooms.

Blackball

Just as intriguing as its name, the Blackball variety of cornflower offers deep, dark maroon blooms that can almost appear black in certain light.

These eye-catching garden blossoms adorn sturdy stems adorned with gray-green leaves, providing a striking contrast.

Dwarf Blue Midget

Standing short but packing a punch with its garden beauty, the Dwarf Blue Midget showcases compact plants laden with fluttering blue blooms.

This variant is perfect as a bedding plant and its shorter stems warrant less need for staking, unlike some taller relatives.

Burgundy Beauties Mix

A blend of deep reds and purples, the Burgundy Beauties Mix is characterized by their robust rosettes. The flowers are incredibly prolific and popular amongst garden pests.

Despite these challenges, their beautiful color and resilience continue to increase their popularity among gardeners worldwide.

How to Plant Cornflower From Seed

Selecting the Ideal Location

Cornflowers are sun-loving plants and thrive best in full sun. Choose a location in your home garden that receives plenty of sunlight and has well-drained soil to prevent rot.

A site with poor drainage or not enough air can lead to various garden pests such as aphids, mealybugs and leafhoppers making it their home.

Preparing the Soil

Annual cornflowers prefer well-drained soil. Prepare the ground by removing any weeds or stones and work in some organic matter to improve soil texture and drainage.

Sowing the Seeds

Sow seeds of cornflower directly into the prepared soil. These slender gray-green leaves will slowly rise from the seeds, giving birth to stems that will hold the brilliant blue flowers that make cornflower a darling of florists and a popular choice for wedding boutonniers.

Aim to thin seedlings around 20 cm apart to ensure not only enough air but an ample amount for the buds to develop without competition.

Caring for Cornflower

Cornflowers are relatively low-maintenance plants. As they grow, ensure they receive ample sunlight and water. While they’re resistant to most common plant diseases, watch out for signs of rust.

Furthermore, staking the plants may be necessary if you notice the stems struggling to support the weight of the blooms.

How to Propagate Cornflower

Step 1: Choose the Right Location

Cornflowers thrive best in a spot that gets full sun throughout the day. These plants prefer well-drained soil to prevent root rot, which can occur if the soil stays too wet. A combination of loamy and sandy soil can provide this perfect balance.

Consider a spot in your home garden that will draw pollinators such as butterflies and bees, which favor cornflowers for their brilliant blue flowers.

Step 2: Preparing the Soil and Sowing the Seeds

Before you sow the seeds, turn the soil over using a garden fork. Ensure it is loose and free from any garden pests, such as aphids, mealybugs, or leafhoppers. Directly sow your cornflower seeds into the final growing positions, as these annual

Cornflowers do not like to be transplanted. Broadcast the seeds gently over the soil, aiming for a light scattering so seedlings won’t be overcrowded and will have enough air.

Step 3: Care for Your Seedlings

In a few weeks, the seedlings will emerge from the soil. Ensure you remove excess seedlings once they are large enough to handle, thinning them out to around 20 to 25cm apart.

At this stage, regularly check your emerging cornflower stems for any signs of rot or rust. If you see any, immediately remove the affected plants to prevent it from spreading to the healthy ones.

Step 4: Grow and Enjoy

Cornflowers require very little maintenance once established. Their gray-green leaves are sturdy, and their crisp blue blooms are fairly resistant to lighter bouts of bad weather.

How to Pot or Retpot Blue Cornflower

Step 1: Choosing the Right Pot & Soil

Before you sow the seeds of the cornflower, also known as blue cornflower or bachelor’s button, select a pot with good drainage to prevent waterlogged soil leading to rot and rust.

Due to the cornflower’s popularity as a bedding plant, it’s widely available at garden centers. Pair the pot with a well-drained soil mix enriched with organic matter.

Cornflowers prefer slightly alkalized soil, so you might need to adjust the pH based on your soil test results.

Step 2: Sowing the Seeds

One popular member of the Asteraceae family is the annual cornflower, well respected for its brilliant blue flowers – a rarity as this is the only true natural color for garden blossoms.

The best time to sow cornflower seeds is during full sun, which provides the best conditions for germination. They should be lightly covered with soil, kept moist but not soaking, and spaced out to allow for growth.

Thin seedlings once they’re large enough, leaving about a foot between each plant.

Step 3: Staking and Post-Planting Care

Staking may be necessary for taller cornflower varieties, especially during windy conditions.

Regular watering, allowing the soil to dry out between each session, is crucial to prevent the stems from becoming waterlogged, and to prevent gray-green leaves and flowers from wilting or getting mottled with spots caused by aphids and mealybugs.

This variety of flower can provide brilliant shades of crisp blue under full sunlight, encouraging pollinators like butterflies and bees to visit.

Common Pests and Plant Diseases for Cornflower

Aphids

These garden pests are common across a widespread group of plants, including the royal blue blooms of the Bachelor’s Button.

Aphids attach themselves to the stems and underside of leaves, sucking the sap and potentially introducing harmful viruses. A heavy infestation can cause leaves to curl, yellow, and drop prematurely.

Mealybugs

Effecting the sturdy gray-green leaves, brilliant blue flowers, and crisp blue buds of the beloved Cornflower, mealybugs are a threat not to be overlooked.

They are small, soft-bodied insects that coat themselves in a white, powdery wax layer which insulates them against pesticides and environmental influences.

They cause damage by sucking the sap from the host plant and create an unsightly and difficult to remove sooty, sticky exudates.

Leafhoppers

Notorious for infesting garden blossoms, leafhoppers suck out the plant’s juices causing yellowing or browning of leaves, stunted growth, and even plant death in severe cases.

In addition, they excrete honeydew attracting ants and fostering the growth of sooty mold on leaves.

Rot

Cornflowers, a member of the asteracea family, grown in conditions with poor air circulation or overly waterlogged soil can easily fall prey to rot, particularly root rot.

This disease causes wilting, yellowing of leaves and stunted growth. Proper drainage and spacing during planting can help mitigate this risk.

Rust

Rust is a fungal disease that can reduce the longevity and vitality of cornflowers. Symptoms include rust-colored pustules on the underside of leaves, which can spread, causing leaf drop and weakening the plant.

Warm, moist conditions can expedite the spread of rust, so proper spacing, watering at the base of the plant, and using a broad-spectrum fungicide can help manage this disease.

Common Plant Problems and Solutions for Cornflower

Poor Flower Production

In some cases, a cornflower may produce fewer blooms or appear less vibrant. This can be a result of the plant not receiving full sun.

Cornflowers are sun-loving plants and for best flower production, they should be planted in a location that receives ample sunlight. Additionally, while cornflowers can grow in a variety of soils, they prefer well-drained soil.

Competition from Weeds

Weeds can outcompete cornflowers, particularly during seedling stages. To avoid this, sow seeds directly to the desired spot in your home garden.

As the plant begins to grow, thin seedlings to establish a strong, single plant. Adding a layer of mulch around the plant can also help deter weeds.

Legginess

Cornflowers, if planted in too much shade or overly-rich soil, may become leggy – growing tall and thin with few flowers. This can be managed by staking the stems to help them stay upright and reducing the nitrogen level in the soil.

 

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Hydroponic Flowers: The Best Choices for Indoor Gardens

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