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Ageratum
Ageratum houstonianum
Ageratum blooms from June through October.
Mature size, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not.
Growing Ageratum
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 10–11. Expect it to reach about 12 in tall and 12 in wide at maturity, in roughly 1 year.
When to plant Ageratum
Wait until all danger of frost has passed, then plant out Ageratum into warm soil; in most zones that means late spring. Planted then, it flowers from June to October.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 10 in January.
Comes in 4 varieties across 3 colors
Same plant, same care - pick the color you are growing.
Good to know about Ageratum
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Chronically toxic to grazing livestock: eaten over weeks it causes fatal liver damage. Low risk to pets and people, but never use any part as food. per Veterinary and Human Toxicology
Worth knowing
The fuzzy powder-puff look comes from dense heads of tiny tubular florets with no petals; it is in the daisy family despite looking nothing like one. per NC State
Size depends on cultivar
Dwarf bedding types stay about 0.15 to 0.3 m tall; the species and tall cut-flower cultivars reach 0.6 to 0.9 m, two to three times bigger. Check the label. per Wisconsin
Deer and rabbit resistant
Deer and rabbits rarely browse it, so it is a good pick where they are a problem. Resistant, not fully deer-proof: hungry deer may still sample it. per NC State and UGA
Feeds butterflies until frost
It flowers from early summer until the first frost, giving butterflies a steady nectar supply. A common, moderate (not top-tier) choice for butterfly plantings. per NC State and University of Illinois
Deadheading depends on cultivar
Older seed strains turn brown and ragged unless you deadhead; many modern hybrids are self-cleaning and need little. Deadheading also prolongs bloom and cuts disease. per Wisconsin and University of Illinois
Head off mildew and mites
Powdery mildew loves shade, crowding and humidity; spider mites flare in hot, dry spells. Space for airflow, water at the base in the morning, and keep soil evenly moist. per University of Illinois
What pairs well with Ageratum
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Rock Cress
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; evergreen, so the bed keeps its shape through winter; lower at 4 in, for the front of the border.
Sneezeweed
Shares full sun and moderate water; its seed heads stand through winter, for structure and the birds; both offer pollinator forage; taller at 3.3 ft, for the layer behind it.
Perennial Sunflower
Shares full sun and moderate water; its seed heads stand through winter, for structure and the birds; both offer pollinator forage; taller at 4.9 ft, for the layer behind it.
Rosemary
Shares full sun and low to moderate water; blooms in early spring, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Viburnum
Shares full sun and moderate water; blooms in mid spring, before this one opens; stands well above at 6.6 ft, a canopy to plant beneath; both offer pollinator forage, in different months.
Lilac
Shares full sun and moderate water; blooms in mid spring, before this one opens; stands well above at 9.8 ft, a canopy to plant beneath; both offer pollinator forage, in different months.
Mock Orange
Shares full sun and moderate water; opens in late spring and overlaps into this one's season; stands well above at 8.2 ft, a canopy to plant beneath; a soft color beside the blue.
Pansy
Takes full sun to part sun and moderate water; opens in early spring and overlaps into this one's season; lower at 8 in, for the front of the border; purple sits close to blue on the wheel.
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