Growing Ageratum

Ageratum

Ageratum is an annual plant that is native to Mexico with four varieties that are native to the United States and about 60 different varieties.

Ageratum is also commonly known as a floss flower and is a member of the aster plant family.

PLANTING AGERATUM

Ageratums can be sown straight into the soil or started 8 to 10 weeks before the last frost in a cardboard seed starting tray.

They prefer full sun but they will do fine in partial shade with slower growth and fewer blooms.

Once sown, they take 7 to 10 days to germinate.

Dwarf varieties should be planted about eight inches apart and with other varieties, they should be planted about one foot apart.

They grow best in hardiness zone 10 and 11 with the soil pH ranging between 5.8 through 6.2.

For best results, it is recommended before planting ageratums to till compost into the soil which is known as amending the soil.

This will provide nutrients to the soil, helps with water retention, and will help to keep the soil loose which will make it easier for the roots to grow.

AGERATUM USES

Ageratums are typically used by gardeners in flower beds, rock gardens, raised garden beds, in potting containers, as a border, along pathways, or in mass as a display.

FERTILIZING AND WATERING

Ageratums don’t require much fertilizing if the soil was amended but a granular slow-release fertilizer that is balanced or a homemade liquid fertilizer can be used.

If the leaves are turning yellow and the soil is moist enough then they need to be fertilized.

Ageratums require constantly moist soil when they are becoming established but afterward, they require about one inch of water per week.

They tend to wilt quickly if the soil is allowed to dry out.

MULCHING

Mulching ageratums will help the soil retain water which will reduce the amount of time it takes to water them.

The thickness bed of the mulch is best between 1 to 2 inches thick and may need to be reduced if you live in a moist and rainy climate or if you are is getting more rain the usual.

The mulch will also help with weed control which is important because they don’t compete well with weeds.

It is best to add new mulch every year as the older mulch breaks down.

BLOOMS

Ageratum Blooms

Ageratum has spiky ball-shaped blooms that are mostly different shades of blue but they also come in red, purple, pink, and white that appear from June until the first frost.

Their blooms attract bees and butterflies in large numbers.

Ageratums don’t require deadheading because the plant will rebloom on its own until the first frost.

If the blooms are allowed to go to seed then they will sprout next year, if you don’t want this to happen remove the wilted bloom before it produces seeds.

PRUNING

When ageratums are young the new growth can be clipped off to encourage the plant to bush out which will increase the number of blooms.

PESTS

Ageratums don’t have many pests to worry about but there are a few to watch out for.

DISEASES

Ageratums that are planted close together can develop mold and mildew issues during times of high humidity.

If this is the case then pruning and preventive measures may need to be taken.

VARIETIES

Most varieties of ageratums are hybrids with different heights and shades of color.

BLUE HORIZON AGERATUM

Blue horizon ageratums are an F1 hybrid, meaning that it is the first generation that is different from the parent plant.

  • Plant size – grows to about 30 inches tall and 8 inches wide
  • Drought tolerant – yes
  • Blooming colors – purplish-blue
  • Bloom attract – butterflies and bees
  • Foliage – spade-shaped foliage with jagged edges that grow to about 2 inches long
  • Deer resistant – yes

HAWAIIAN ROYAL AGERATUM

Hawaiian royal ageratum is known for its long-lasting blooms that appear in early spring.

  • Plant size – grows to about 6 inches tall and 8 inches wide
  • Drought tolerant – yes
  • Sun exposure – full sun to partial shade with fewer blooms
  • Blooming colors – blue
  • Bloom attract – butterflies and bees
  • Foliage – spade-shaped leaves with jagged edges that grow to about 2 inches long
  • Deer resistant – yes

SOUTHERN CROSS AGERATUM

  • Plant size – grows to about 2 feet tall
  • Drought tolerant – yes
  • Sun exposure – full sun to partial shade with fewer blooms
  • Blooming colors – pale blue and white
  • Bloom attract – butterflies and bees
  • Foliage – spade-shaped leaves that grow to about 2 inches long
  • Deer resistant – yes

RED FLINT AGERATUM

  • Plant size – grows to about 3 feet tall and 1 and a half feet wide
  • Soil pH – 5.8 through 6.2
  • Drought tolerant – yes
  • Sun exposure – full sun to partial shade with fewer blooms
  • Blooming colors – red
  • Bloom attract – butterflies and bees
  • Foliage – spade-shaped leaves that grow to about 2 inches long
  • Deer resistant – yes

DONDO WHITE AGERATUM

  • Plant size – grows to about 2 feet tall and 1 foot wide
  • Drought tolerant – yes
  • Sun exposure – full sun to partial shade with fewer blooms
  • Blooming colors – white
  • Bloom attract – butterflies and bees
  • Foliage – spade-shaped leaves that grow to about 2 inches long
  • Deer resistant – yes