Eupatorium fistulosum f. albidum 'Ivory Towers'

Eupatorium are one of those plants that fall into the ‘naturalistic’ category. They share the physical characteristics of native species, albeit transplanted to another country. They tend to have simple flowers rather than highly bred doubles, and the overall form gives the impression of a wild plant rather than an exotic.
Eupatorium excels as a conventional perennial and is invaluable for the late-summer border. They flower fairly late in the season and are a good replacement plant, filling the space left by early flowering species. They are splendid companions for other late perennials such as Echinacea, Rudbeckia and Helenium. Ornamental grasses also make for happy bedfellows. Eupatorium are also an extremely useful as a landscape plant, where there is a need to make a gentle transition from a highly gardened environment to the natural landscape beyond. It is a plant with a powerful presence that will add colour and form to the late-summer garden and will carry the interest through to autumn and beyond.

Introduced in 2010, Eupatorium fistulosum f. albidum ‘Ivory Towers’ is relatively new to our gardens, yet has already been awarded the Award of Garden Merit by the RHS.
This architectural and eye catching plant bears generously clusters of ivory-white blooms which are long-lasting and beloved by butterflies. If sown early in the season 'Ivory Towers' will flower the first year, and will grow to about half the eventual mature size in its first season. The second season it reaches its full, impressive, towering height. Sited in full to mostly full sun planted in fertile moisture-retaining soil the plants may grow to 150 to 180cm (5 to 6ft) tall. They begin flowering late in the season in July with the impressive show continuing right through to late September.

• Awarded the RHS Award of Garden Merit
  Eupatorium fistulosum f. albidum has been awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).

Position:
Eupatorium fistulosum is native eastern North America. In the wild it can be found in pastureland and at the edges of woodlands and streams. It thrives in garden soils that are reasonably fertile and not too dry. The plants are also useful for planting in damp areas, they are naturals near ponds, streams, and pools.
It is a tall plant that needs a little space, when used in a border it is best located near the back. In good growing conditions plants may grow 120 to 150cm (4 to 5ft) in height and reach half as much across, but thanks to its strong stems, it does not need staking.

Sowing: Sow seed in cool weather in autumn or early spring.
For spring sown seedlings sow from January to late June, early sowings will flower the same season. Sowing in autumn is best done in September or October once the heat of summer has gone.
Sow the seeds very finely onto the surface of trays or pots containing moist seed compost. Just cover with a sprinkling of sieved compost or vermiculite. Place in a plastic bag or cover pots or trays with perspex and place in a position to maintain an optimum temperature of 20°C (68°F)
Keep the compost moist but not saturated, water from the base of the container and drain thoroughly. Germination usually takes 21 to 40 days at 18 to 24°C (65 to 75°F). Remove the cover once the seedlings begin to germinate to allow air to circulate, otherwise they may suffer from damping off disease.
Thin (prick out) seeds as they become large enough to handle into 7cm (3in) pots, leaving the seed trays intact for other seedlings that may germinate later. Harden off young plants gradually for 10 to 15 days before planting out.
In poor soil it is worth incorporating some organic matter before planting. Plant out 100cm (39in) apart into moist but well drained soil in sun or part shade.
Water deeply to encourage roots to grow deeply, resulting in a healthier, more drought tolerant plant. Avoid overhead watering if possible.

Cultivation:
Given that many species grow naturally in damp or wet habitats, the plants may need additional water in the hottest periods of the summer to avoid wilting. While normally sturdy-stemmed, plants may bow a bit under the weight of the large flower heads, especially after overhead irrigation or a heavy rainfall. Deadheading not only keeps plants looking neat after flowering but also deters self-sown seedlings.
Larger selections can be given the ‘Chelsea chop’ and cut back to 60cm (24in) or so in late spring or early summer to reduce their ultimate size. Plants that are cut back typically bloom at or near the regular time but the flower heads are usually a little smaller.
Division is necessary only when plants outgrow their location.

Plant Uses:
Beds and borders, Prairie and naturalistic Garden, Cottage/Informal, Wildlife, Bee and Butterfly gardens. Stream or pond side. Low-maintenance.

Origin:
Eupatorium fistulosum is native to damp meadows, thickets and coastal areas in eastern North America.
The cultivar Ivory Towers was introduced in 2010

Nomenclature:
The species name Eupatorium derives from the Greek name Mithridates Eupator, King of Pontus about 115BC who is said to have discovered an antidote to a commonly used poison in one of the species.
The species name fistulosum derives from the Latin fistulosus, meaning hollow or tubular, and usually referring to the stalks.
The subspecies albidum derives from the word alba and refers to the white colour of the flowers. It derives from the Latin word album for a ‘writing tablet’ now used to mean ‘white’ in reference to the tablets historically being white.

In North America, Eupatorium species are commonly called Joe Pye weed, with Eupatorium fistulosum being Hollow Joe Pye weed in reference to the hollow stems.
There are multiple versions of how it got its name. One common story says that Joe-Pye, or possibly named Jopi was a Native American medicine man who used Eupatorium to treat a variety of ailments. Common names can be colorful, folkloric, and often regional in nature, and may be misapplied to a whole group when they actually refer to one species. For example, referring to all of the species as Joe-Pye weed is inaccurate, Joe-Pye weed needs the appropriate descriptor attached, such as Spotted, Hollow, or Sweet-Scented, to ensure the right species is being referenced.
In the wild Eupatorium can be found in pastureland and at the edges of woodlands and streams, where it forms dense colonies. This might explain the inclusion of the word ‘weed’ in its common name, Joe Pye weed. In a garden setting it is far better behaved, forming decent clumps but never straying.

Eupatorium, a formerly large genus in the Asteraceae, the aster family, has been split up in recent years resulting in species being reclassified under genera such as Eutrochium, Conoclinium, and Ageratina.
Most of the commonly cultivated temperate species fall within these new genera, although some species remain in Eupatorium. A number of these species are wildflowers in the eastern United States, while others are found across a broad geographic range in North and South America, Europe, Africa, and Asia.
So, although many gardeners are familiar with the old name of Eupatorium, the correct name for this particular species, Eupatorium fistulosum f. albidum 'Ivory Towers' is now Eutrochium fistulosum f. albidum 'Ivory Towers'.