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

Description and botany

Chionanthus, also nicknamed “snow tree” or “fringe tree”, is a bush in family Oleaceae, like lilac, ash and olive. For a long time the genus contained only two species of trees and bushes, Chionanthus virginicus hardiest and most widespread in our gardens, and Chionanthus retusus, native to woods, thickets and stony hills of south‑east United States for the first, and Asia for the second.

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

Chionanthus virginicus and Chionanthus retusus have quite different appearances. In Chionanthus retusus, beautiful grey‑ochre bark peels or becomes deeply channelled with age.

Chionanthus bears a remarkable rather late flowering, which appears with the foliage and almost entirely overwhelms it. Delayed, flowering occurs only on plants aged 4 to 10 years. In May–June, an abundant white, plume‑like flowering covers the vegetation like a floccose cloud, earning the bush its nickname of “snow tree” or “snow flower”.

Chionanthus virginiana – botanical illustration by Mary Vaux Walcott

Flowers, very small and finely star‑shaped, 1 to 2 cm long, consist of four fine pure‑white linear petals resembling ribbons or threads. Gathered in very dense panicles that can reach 20 cm long, they are upright in Chionanthus retusus, longer and pendulous, evoking fringes in C. virginicus, and even more attractive when seen from below!

They exhale a slightly mentholated scent.

Chionanthus is dioecious, meaning there are male and female trees: fruiting occurs only if male and female plants stand side by side. However, some Chionanthus are hermaphrodite and can fruit in absence of a nearby male plant, so fruiting is therefore very unpredictable.

At end of summer, on female plants, flowers give way to small waxy berries, oval drupes blackish‑blue or purplish‑blue that are a favourite with birds.

Foliage forms a light, glossy background of greenery appearing as large umbels from a distance. In spring, shoots bear a deciduous vegetation differing noticeably between species. Leaves are opposite, generally elliptical, measuring 4 to 12 cm long in Chionanthus retusus versus 15 to 25 cm in C. virginicus. They are glossy above and have a wooly underside in Chionanthus retusus. From bright to dark green, they turn golden yellow in autumn.

Hardy, Chionanthus does not fear cold (down to -25°C for C. virginicus), and thrives widely in France, preferring warm summers and cold winters of continental climate.

It is a very easy bush to grow that flourishes in sun, in humus‑bearing, cool, well‑drained soils with a preference for acidic, non‑calcareous soils.

Its compact yet elegant silhouette and fairly slow growth make Chionanthus a bush that suits natural and naturalistic gardens and wild settings, even in small city gardens, creating attractive focal points. It can be grown alone as a specimen in centre of a heather soil bed or in groups with other spring‑flowering bushes, for example as a country or flowering hedge.

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

In former times, Native Americans crushed 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, which is an Asian arborescent species capable of reaching 20 m in its native habitat, more sensitive to severe frosts, with decorative bark and with upright panicles of flowers, and the American species Chionanthus Virginicus, hardier, whose flowering with pendulous panicles is spectacular.

Our favourites

Chionanthus virginicus

Very hardy, most widespread species in our gardens. With white flowering in long, fringed panicles, slightly scented, it is a standout in natural gardens, in mixed borders or in a flowering hedge.

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

See the product sheet

Chionanthus retusus

Abundant white flowering overwhelms its foliage. Sumptuous in spring in a bed of heather soil bushes or in a country-style hedge.

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

See the product sheet

Planting

Where to plant Chionanthus or fringe tree?

Capable of good hardiness that varies with species (-25 °C for Chionanthus virginicus and -15 °C for C. retusus), Chionanthus can withstand negative temperatures if sheltered from cold, drying winds, which ensures excellent performance in all regions.

It needs several years to adapt before flowering well and only thrives in full sun, where it produces maximum flowers. It will tolerate a shaded position in southern regions. Its foliage copes well with urban pollution, making it a fine choice for city gardens.

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

Very versatile, this beautiful, poetic bush is used both as a specimen to enrich a meadow-style border with heather-soil bushes or to form a lovely flowering, meadow-like 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

Chionanthus appreciates soil that has been deeply worked with turf or potting compost. It is used in borders, alone, in groups of three bushes or as a loose hedge at a density of 1 young plant per m².

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

More advice for successful planting a bush on our information sheet!

Planting fringe tree in a pot

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

• In a sufficiently large container, spread clay balls or pumice
• Place your bush in a mix of turf and good planting potting compost
• Water fairly regularly in summer as soon as soil is dry

Maintenance, pruning and care

Chionanthus is an easy-to-care-for bush and very hardy that is free from pests and diseases. In case of excess lime in the soil, it can be subject to chlorosis, a disorder causing discoloration and yellowing of leaves: add heather soil at planting.

During dry weather, monitor water needs, especially in early years. It is preferable to mulch the base annually, in May, to retain some moisture.

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

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

Pruning is not necessary, not least because flowering only occurs on old wood. A light annual pruning is sufficient: remove dead or poorly placed wood towards end of winter, in February–March. You can also cut lower branches if you wish to form a trunk.

Multiplication

If Chionanthus or “fringe tree” can be multiplied by sowing or by grafting onto ash, we recommend layering, which is easier to do.

By layering

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

• Lower one of the low branches to the foot of the tree
• Remove leaves and shoots from this 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
• Raise the tip and stake the above-ground section
• The following spring, or even the following autumn, separate the layer from the mother plant once it has sufficient roots
• Replant straight away in open ground

Pairing the snow tree in the garden

With its original, gracefully tousled silhouette, Fringe tree brings in late spring a delightful touch of freshness to natural gardens, wild or English-style, to a large meadow-like mixed border, mixed into a flowering hedge, as a striking punctuation in the middle of a short grass meadow or as a romantic container sited on the terrace.

This bush is ideal in small gardens and city gardens.

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

It easily finds its place in a bush bed of heather soil such as Cornus, Camellias, deciduous Azaleas, Hydrangeas, Rhododendrons, Viburnums, Kalmias or Japanese Andromedas.

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

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

In a romantic garden, magnolias, white lilacs, amelanchiers, buddleias and roses will accompany or take over from its flowering with their delicate hues.

In autumn, its foliage will blend wonderfully with Cercidiphyllum japonicum (“Caramel Tree”), Leucothoe, Acer or deciduous euonymus.