Ageratina altissima
White snakeroot, Mist flower, Sanicle, Richweed, Snakeroot, Floss flower
Also known as Eupatorium rugosum, Eupatorium ageratoides
- Height × spread
- 1m × 1m
- Position
- Tolerates full sun, likes part shade, likes light shade
- Hardiness
- Very cold to -20C (RHS H6)
- Flowers
- Summer
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
This has broad conical leaves with toothy edges, coloured bright green. They arch out from the upright stems. The flowers are rather distinctive. They form branching heads of little white pompom like flowers, each cluster distinct and separate. Their slender stamens stand upright and shine like needles in the light. It flowers in August and the flower heads turn brown rather too quickly. These plants can poison livestock so place with care.
- Flower colour
- White
- Foliage colour
- Green
- Variegated
- No
- Scent
- No
- Shape
- Cube
- Height
- 1m
- Spread
- 1m
- Season of interest
- Summer
- Flowers in
- Summer
- Evergreen
- Deciduous
- Sun or shade
- Tolerates full sun, likes part shade, likes light shade
- Soil type
- Chalk, Loam (normal)
- Soil pH
- All types
- Drainage
- Moisture retentive soil, Damp and wet soil
- Hardiness
- Very cold to -20C (RHS H6)
- Borders & containers
- Borders
- Use for
- Ground cover
- Hazards
- No
Spring
Spring - late · Outdoors
Feed with slow release fertiliser
Apply a general purpose slow release fertiliser, spreading it around the root area of the plant as it is coming into growth. (Or apply a liquid feed at regular intervals throughout the growing season.)
This is a simple way to provide a nutrient boost as a single annual procedure.
Spring-Autumn · Outdoors
Water to keep the soil moist
For best results, this plant needs soil that is always moist. Water deeply and regularly as soon as soil appears dry. Even for established plants in the ground, a dry week can cause problems with some soils. Check plants in pots more often, especially in hot weather. Or install an automatic irrigation system which will do the hard work for you, even when you are away on holiday.
Without regular watering some plants never fully regain their beauty.
Spring - early-mid · Planting
Divide when too large
The plant can be divided if it becomes too large or another plant is required. This may involve physically dividing the clump in two, removing offsets or small bulbs or dividing rhizomes. The new plants can be grown in pots or planted in the ground.
Spring-Autumn · Planting
Trim dead flowers to prevent self-seeding
Note on self-seeding: If you do not want this plant to set seed it is necessary to promptly remove the spent flowers as they fade.
It's possible to carefully remove the seed heads, complete with seed, and then place them in areas where you would like new seedlings to grow.
Summer
Summer · Planting
Prune lightly after flowering
Give the plant a light haircut, generally tidying it up and removing any shoots that are wayward or damaged in any way. Dead flowers can be cut off if this is practical - the shrub may have too many, or they may be hard to reach.