Dictionary of Flowers: Ageratum (Floss Flower)

Ageratum (Floss Flower) looks like thistle blooms. Image used under a Creative Commons licence with the kind permission of Serres Fortier and Flickr
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Ageratum (Floss Flower) looks like thistle blooms. Image used under a Creative Commons licence with the kind permission of Serres Fortier and Flickr

  • Agaeratum (Floss Flower)
  • Frost sensitive perennial in Z 9-11, sold as an annual
  • Height: 8" Width: 8"
  • Sun
  • Blooms: summer to fall
  • Attracts: butterflies
  • Soil: fertile, free draining
  • Diseases: powdery mildew
  • Pests: aphids, thrips, spider mites

TWOSHORTPARAGRAPHSGOHERE

Ageratum is native to Central America. There are lots of species in this genus, but the ones favored for garden use are ageratum houstonianum and ageratum hybrids.

Their botanical name is derived from the Greek, meaning "non aging".

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

They are low, mounding plants with clumps of small, fuzzy flowerheads in blue, white, pink and blue-purple.

They are normally grown as annuals. They can be bought as nursery plants, started indoors from seed, outdoors in warmer climates, or rooted by layering a stem from the parent plant. 

Ageratums are easy plants to grow, just requiring pinching back when young to maintain bushy, compact plants and regular monthly fertilizing and deadheading.

If the plants decline, cut back severely and continue watering. In very hot areas, they prefer some protection from hot afternoon sun.

If bought as nursery plants, they transplant easily.

Ageratum can be easily grown from seed. Start indoors six to eight weeks before last frost date.

Press the seed into moist growing mix and do not cover, as they require light to germinate. At normal room temperature, they germinate in five to 15 days.

After germination, move the seedlings to a cooler location, around 60°F. Harden off young plants before transplanting outdoors and wait till soil has warmed up before setting in their permanent location.

They can be sown outdoors in areas with long growing seasons. In frost-free areas, they can be grown for fall-winter color.

They prefer regular fertilizing and watering. Keep the soil moist, but not soggy. If planted in the ground, they benefit from mulching to conserve moisture, as they are shallow rooted plants.




IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

If pest problems appear, treat with insecticidal soap. Powdery mildew can be avoided by watering in the morning and giving the plants good air circulation.

They attract butterflies and other pollinators. However, they can be poisonous to cattle if ingested.

Popular varieties:

  • Ageratum houstonianum 'Blue Mink' – large, powder blue flowers
  • Ageratum houstonianum 'Blue Danube'  - early bloomer, bright blue flowers
  • Ageratum hybrid 'Artist' series – blue purple flowers, small and fluffy 
  • Ageratum hybrid 'Leilani Blue' – clear blue flowers on strong plants

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Click to see Anagallis (Pimpernel)Click to see Anagallis (Pimpernel)

Full List of Dictionary of Flowers Entries

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