<em>Chionanthus</em>, snow tree: planting, to grow

Description and botany

Chionanthus, also nicknamed “snow tree” or “fringe tree”, is a bush of Oleaceae family, alongside lilac, ash and olive. For a long time the genus comprised only two species of trees and bushes, Chionanthus virginicus, the hardiest and most widespread in our gardens, and Chionanthus retusus, originating from woods, thickets and stony hills of the southeastern United States for the former, and from Asia for the latter.

Slow-growing, it forms a small rounded bush well branched from the base with a spreading, bushy habit, a little more umbrella-shaped in Chionanthus retusus. Reaching 5 to 10 metres in its natural habitat, it rarely exceeds 3 to 4 m in height with 5 m spread in our latitudes. Often forming several trunks but little higher than wide, it is a valuable asset in small gardens.

Chionanthus virginicus and Chionanthus retusus show noticeably different appearance. In Chionanthus retusus, beautiful grey-ochre bark peels or becomes deeply channelled with age.

Chionanthus puts on a remarkable, fairly late flowering, which appears with the foliage and almost entirely engulfs it. Taking its time, flowering only occurs on plants aged 4 to 10 years. In May–June, abundant white, feathery flowering covers vegetation like a floccose cloud, earning the bush its nickname “snow tree” or “snow flower tree”.

Chionanthus virginiana – botanical illustration by Mary Vaux Walcott

Flowers are very small, finely star-shaped, 1 to 2 cm long, made of four narrow pure-white linear petals resembling ribbons or threads. Gathered in very dense panicles up to 20 cm long, they are erect in Chionanthus retusus, longer and pendulous resembling fringes in C. virginicus, and look even lovelier from beneath!

They give off a slightly mentholated scent.

Chionanthus is dioecious, meaning there are male and female trees: fruiting only occurs if male and female plants grow side by side. However, hermaphrodite Chionanthus exist, capable of fruiting in absence of a nearby male, so fruiting is therefore very irregular.

At late summer, on female plants, flowers give way to small waxy berries, oval drupes bluish-black or purplish-blue that are relished by birds.

Lush foliage forms a light, glossy green backdrop, appearing from afar as large umbels. In spring, shoots are clothed with deciduous growth differing between species. Leaves are opposite, usually elliptical, measuring 4 to 12 cm long in Chionanthus retusus versus 15 to 25 cm in C. virginicus. Shiny above and with a white wooly hair underside in Chionanthus retusus. From bright to dark green, leaves turn golden yellow in autumn.

Hardy, Chionanthus tolerates cold (down to -25 °C for C. virginicus) and grows well across France, favouring warm summers and cold winters of continental climate.

It is a very easy bush to cultivate that thrives in sun, in humus-bearing, cool and well-drained soils with a preference for acid, non-calcareous ground.

Its compact yet elegant silhouette and fairly slow growth make Chionanthus a bush that fits natural and naturalistic gardens and wild gardens even in small city gardens, forming attractive focal points. It grows well alone as a specimen in centre of a heather soil bed or in groups associated with other spring-flowering bushes, for example in a country or flowering hedge.

Chionanthus retusus: bush silhouette in flower / flowering / fruiting / autumn foliage

Historically, Native Americans pounded roots and bark to treat skin inflammations.

Main species and varieties

Only two species of Fringe tree are found in our gardens: the Chionanthus Retusus, an Asian arborescent species capable of reaching 20 m in height in its native habitat, more sensitive to severe cold, with decorative bark and panicles of erect flowers, and the American species Chionanthus Virginicus, hardier, whose flowering with pendulous panicles is spectacular.

Our favourites

Chionanthus virginicus

Very hardy, it’s the most widespread species in our gardens. With its white flowering in long fringed panicles, slightly scented, it is a staple of all natural garden styles, in a shrub border or in a flowering hedge.

• Flowering time May to July
• Height at maturity 3 m

See the product sheet

Chionanthus retusus

An abundant white flowering that overwhelms its foliage. Sumptuous in spring in a shrub bed on heather soil or in a country hedgerow.

• Flowering time June, July
• Height at maturity 3 m

See the product sheet

Planting

Where to plant Chionanthus or fringe tree?

With a variable good hardiness depending on species (-25 °C for Chionanthus virginicus and -15 °C for C. retusus), the Chionanthus can withstand negative temperatures if sheltered from icy, desiccating winds, which ensures perfect resistance in all regions.

It requires several years to establish before flowering and only thrives in full sun, where it produces most flowers. It will tolerate some shade in southern France. Its foliage copes well with urban pollution, making it a choice bush for city gardens.

It will adapt to any good, deep, well‑drained garden soil, but prefers richer, non‑calcareous, rather acid soil that stays cool in summer. Chionanthus retusus, or “Chinese fringe tree”, is even less tolerant of lime in the soil than its American cousin. However, grafted onto an ash (Fraxinus ornus), this acidophilous plant can be planted in calcareous ground.

Very versatile, this beautiful bush of rare charm can be used as a specimen to enrich a meadow‑style border with bushes for heather soil or to form a pretty flowering, country‑style hedge.

With its slow growth, it also suits small city gardens as well as cultivation in a large pot on a sunny terrace or balcony.

When to plant Chionanthus or fringe tree?

Planting Chionanthus can be done in spring from February to May or preferably in autumn from September to November, to encourage rooting before winter.

How to plant Chionanthus?

In open ground

The Chionanthus appreciates deeply worked soils with turf or good planting compost. Use in a border, alone, in groups of 3 plants or as an informal hedge at a rate of 1 plant per m2.

• Dig a hole 2 to 3 times wider than the pot
• Break up the soil thoroughly
• Make a good bed of gravel at bottom of hole
• Mix half garden soil with turf, potting compost or compost
• Stake firmly
• Plant bush at collar level
• Backfill while keeping bush upright and firm soil gently around base
• Firm the soil at foot of tree
• Mulch base with a layer of leaf mould or compost to keep soil cool in summer
• Water well during first weeks to encourage establishment

More tips to successfully plant a bush on our advice sheet!

Planting fringe tree in a pot

Slow growth of the Chionanthus allows cultivation in a large pot on a terrace, where it will release a delicate perfume in late spring.

• In a sufficiently large container, spread clay pebbles or pumice
• Plant bush in a mixture of turf and good planting compost
• Water fairly regularly in summer as soon as soil is dry

Maintenance, pruning and care

Chionanthus is an easy-to-maintain, very hardy bush that suffers from neither pests nor diseases. If soil contains excess lime, it can be prone to chlorosis, a disease causing discolouration and yellowing of leaves: add heather soil at planting.

In dry weather, monitor water needs, especially during first years. It is best to mulch around base every year, in May, to maintain some moisture at its base.

In spring, to stimulate growth and flowering of your Chionanthus you can apply an organic fertiliser.

Repot container-grown specimens every two years into a larger container.

Pruning is not necessary, especially since flowering occurs only on old wood. A light annual tidy-up is enough: remove dead or poorly placed wood towards end of winter, in February–March. You can also cut low branches if you wish to form a trunk.

Propagation

Although Chionanthus or “snow tree” can be propagated by sowing or by grafting onto ash, we recommend layering, which is simpler to carry out.

By layering

Root development of layers is fairly slow, so be patient! Carry out at end of summer.

• Bend one of the low branches down to base of tree
• Remove leaves and stems from that section
• Scrape bark over 5–10 cm with a small knife
• Dig a furrow in soil nearby and bury part of the shoot to encourage rooting
• Backfill the furrow and secure the layer with two metal hooks
• Lift the tip and support the above-ground portion with a stake
• In following spring, or possibly following autumn, separate layer from mother plant once it has developed sufficient roots
• Plant out immediately in open ground

Pairing the snow tree in the garden

With its distinctive, gracefully tousled silhouette, Snow Tree brings in late spring a delightful touch of freshness to natural gardens, wild or English-style, in a large country-style mixed border, blended into a flowering hedge, as a striking punctuation in middle of a short grass meadow or even in a romantic container placed on terrace.

Ideal bush in small gardens and city gardens.

Planting idea: Chionanthus virginicus, Weigela Florida ‘Nana Variegata’, Penstemon digitalis ‘Husker Red’, Calamagrostis acutiflora ‘Overdam’ and Heuchera ‘Bella Notte’

It easily finds its place in a massif of heather soil bushes such as Cornus, Camelias, deciduous azaleas, Hydrangeas, Rhododendrons, Viburnums, Kalmias or Japanese Andromeda.

In spring, simply surround it with a tapetum of spring bulbs or spring-flowering perennials, such as white narcissi, alliums, lilies, Dutch irises, Eremurus, erythrones or late tulips.

To fully enjoy its beauty, plant on a permanent green backdrop composed of conifers and bushes with evergreen foliage that will showcase delicate beauty of its flowers in spring and golden-yellow foliage in autumn.

In a romantic garden, magnolias, white lilacs, serviceberries, buddleias, rose bushes will accompany or take over flowering with their delicate shades.

In autumn, its foliage will harmonise wonderfully with Cercidiphyllum japonicum (‘Caramel Tree’), Leucothoe, Acer or deciduous spindle bushes.