Thursday, July 18, 2024

Ageratum Flowers (Floss Flower) – All you need to know

Ageratum Flowers also known as Floss Flower, comes in different colors like blue, pink and white blooms. The taller varieties of the flowers are best for cutting and displaying in your home, while the dwarf bedding varieties of the flowers are best kept in the garden.

Ageratum Flowers requires a Full Sun / Partial Shade while their sun requirement is a well-drained soil. It operates in Zones of about 5 – 9. Its Height is around 0.5 – 2 feet tall and it Blooms in Mid‑Summer – Mid‑Fall. It also has a unique feature as it is good for cut flowers.

See also: Aconite Flowers – All you need to know

What is Ageratum Flowers (Floss Flower)?

For those new to flower gardening, you may be wondering, “What is ageratum and how is it cultivated?”
Ageratum houstonianum, a native of Mexico, is among the most commonly planted ageratum varieties. Ageratums offer soft, round, fluffy flowers in various shades of blue, pink or white with blue being most common.
Ageratum plants grow from seed or from small seedlings sometimes found in garden centers. More than 60 cultivars of the blue ageratum flower are available, often reaching only 6 to 8 inches (15-20 cm.) when fully grown.
The wild ageratum is a taller specimen that reseeds abundantly, but most available seeds of the ageratum will be from hybrid types. Popular varieties of the ageratum flowers offer a range of blue colors and include the following cultivars:
‘Hawaii‘ – This type has blooms of a royal blue. It flowers early and is one of the most long lasting of the species.
‘Blue Mink‘ – This cultivar has flowers in a powder blue color and reaches 12 inches (30 cm.) in height.
‘Blue Danube‘ – A variety that reaches just 6 to 8 inches (15-20 cm.) and features blooms in a medium blue shade. Pink and white blooming cultivars are available as well, but tend to wither early and take on a worn, brown look.

How to Plant Ageratum Flowers

Ageratum plants may be started from seed when the soil has warmed outside. Cover seeds lightly, as seeds of ageratum plants need sunlight to germinate.
For an early start to blooms of the ageratum flower, start seeds indoors eight to 10 weeks before planting in the spring garden.
Ageratum Flowers

Caring for Ageratum Flowers

An annual and sometimes perennial flower, the ageratum flowers blooms from spring until fall when receiving proper care. Caring for ageratums includes regular watering until the plant is established.
Use warm water to irrigate the plant for a bounty of blue blooms. You should also deadhead spent blooms as needed to encourage more flowers. Growing and caring for ageratums is simple.
Stick with the popular blue blooms of the ageratum, deadhead as needed and enjoy the simple blue flower in your garden this year.

Pruning and maintenance:

While most will require deadheading to encourage new flowers, others will grow up over the spent blooms, covering them up, and may not need deadheading to look good.

Cut back if plants start looking tired or are outgrowing the space; they should rebloom within a week or two.


Plant in well-amended soil that drains well. Ageratum is not fussy about soil pH.

Amendments & fertilizer:

Ageratums are heavy feeders and benefit from regular fertilizing.

Mix a granular slow-release fertilizer into the soil at the time of planting and reapply mid-season, or use a water-soluble fertilizer twice monthly according to package instructions.

Yellow leaves may be a sign that plants aren’t receiving enough fertilizer.

Mulch with organic material such as shredded leaves or compost to suppress weeds and conserve moisture.

Keep mulch several inches away from the base of the plant to avoid crown or stem rot.


Ageratums have shallow roots, so they can quickly dry out and wilt. Provide consistent water at least weekly, or more as needed during warm spells.

To prevent foliar diseases, water in the morning so plants can dry out, or irrigate around the base of the plants rather than overhead.

Diseases and pests:

When planted in the ideal site, ageratums are resistant to most pests and diseases. Too much shade, lack of air circulation, or high humidity can cause fungal diseases such as powdery mildew.

Poor drainage or overwatering can result in root rot. Possible insect problems include spider mites, aphids, and whiteflies.

Deer resistance:

Deer will generally leave ageratum alone, though extreme conditions can result in deer grazing on plants that they wouldn’t otherwise.

Read Also: Nutritional Profile and Introduction to Food Rating System Chart of Cauliflower



Usually grown as an annual; perennial in Zones 10-11.


4 to 36 inches tall, 6 to 18 inches wide.


Full sun to partial shade. Ageratum plants will flower best in full sun; too much shade can result in less blooms and leggy plants. In hotter regions, plants benefit from afternoon shade.

Bloom time:

From late spring to frost.

Color and characteristics:

Also known as floss flower for its floss-like petals, the tiny blooms resemble fluffy pompoms. Flowers are produced in dense clusters in colors of blue, purple, red, white, or pink.

Leaves are medium green and oval or lance-shaped. Plant habit ranges from short and densely compact to upright and loose.


Ageratum can be toxic to grazing animals, causing liver lesions. All parts of the plant are poisonous and may be harmful to pets or humans if ingested. Call poison control or your local veterinarian for advice if necessary.


When to plant Floss Flower:

Plant nursery starts outdoors from late spring to early summer after all danger of frost is past. Sow seed indoors 8 to 10 weeks before your last average frost date.

Seeds can be sown directly outdoors after your average last frost date; however, plants will not bloom until late summer or fall. Ageratums are heat lovers and will fail to thrive if it’s too cold.

Where to plant Floss Flower:

In a bed or container with rich, well-draining soil that will stay evenly moist.

How to plant Floss Flower:

Press seeds gently into the soil mix and don’t cover, as seeds need light to germinate. Keep moist until leaves emerge (5 to 14 days), and transplant outdoors after all danger of frost is past.

For nursery starts, remove plant from the container and gently tease out the roots if potbound.

Dig a hole and place so the top of the root ball is level with the soil surface.

Gently tamp down soil around the base and water well. Space taller varieties 12 inches apart, and shorter varieties 6 inches apart.

Spacing of Floss Flower

Single Plants: 7″ (20cm) each way (minimum)
Rows: 7″ (20cm) with 11″ (30cm) row gap (minimum)

Sow and Plant

Sow tiny ageratum seeds atop moist seed starting mix and gently press them into the surface. Most gardeners buy ageratum seedlings, but only dwarf varieties are widely available as bedding plants.

Space dwarf varieties 8 inches (20cm) apart in all directions; allow 12 inches (30cm) between very tall varieties.


Blue ageratum provides excellent contrast when combined with flowers with orange blossoms. Some varieties produce white or pink blossoms.

Harvesting of Floss Flower

Snip off spent blossoms to keep plants looking neat, and to prolong flowering. Tall varieties make great cut flowers.


White ageratum blossoms go brown as they age, which is not as noticeable in varieties that bloom blue.

Planting and Harvesting Calendar

Want to find out when you can plant this in your garden? We use historical data from your local weather station to calculate the best range of planting dates for your location (see example planting calendar below).


With different forms to choose from, here are some tips to consider:

For beds and borders:

Taller varieties can be planted midway in a border in combination with other annuals and perennials. Shorter types can be sited at the front of a bed or mixed border.

For edging:

Shorter varieties are suitable along pathways.

For containers:

Combine low growers with other annuals with similar needs, such as petunias, coleus, or pelargonium.

For bouquets, flower arrangements, and cutting gardens:

Choose taller varieties with long stems for cutting.

Read Also: Bee Balm Flowers – All you need to Know


There are many ways to incorporate ageratum into your landscape. Here’s how:

  • Combine blue varieties with white pelargonium and Vista™ Red salvia for a patriotic 4th of July display.
  • Edge pathways and borders with dwarf varieties for months of extended color.
  • Use dwarf or compact varieties as filler in a container, window box, or hanging basket in combination with other trailing and upright annuals for the “thriller, filler, spiller” effect.
  • Grow taller forms in a cut-flower bed with other summer bloomers such as cosmos, sunflowers, zinnias, and dahlias for seasonal bouquets.
  • Plant a dwarf variety in a brightly colored ceramic pot and use as a centerpiece on a patio table where the diminutive flowers can be enjoyed up close.
  • Ageratum combines well with other sun-loving annuals. Possible companions include petunias, bunnytail grass, sweet alyssum, African daisy, calibrachoa, and coleus.


Benadine Nonye is an agricultural consultant and a writer with several years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education - PhD Student in Agricultural Economics and Environmental Policy... Visit My Websites On: 1. - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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