Cypress, <em>Cupressus</em>: planting, pruning and care

Description and botany

Genus Cupressus comprises around twenty species that generally inhabit regions with mild winters such as the Mediterranean basin, the west coast of the United States, Mexico, Guatemala, warm humid areas of the Himalaya and western China. Native range of Mediterranean cypress (Cupressus sempervirens), also called Florentine cypress, which is emblematic of Mediterranean regions, is probably Asia where it grows wild from northern Iran to China via Afghanistan and northern India. Its dark, evergreen, spindle-shaped habit associated with rot-resistant wood fascinated ancient Greek and Roman peoples who spread it as far as Ireland. North America, Madagascar, Australia and New Zealand have also adopted it. In return, Lambert or Monterey cypress (Cupressus macrocarpa), native to California, marks Brittany’s Atlantic coast with its robust, massive habit where it serves as a windbreak.

In France, three Cupressus species are mainly grown: sempervirens, macrocarpa and arizonica. The latter, also known as blue cypress, has a conical habit and grey-blue foliage prized as a specimen or as a large hedge plant in not-too-cold climates. Kashmir or Himalayan cypress (Cupressus cashmeriana), which forms a very impressive blue, weeping mass, is rather delicate to grow as it tolerates neither wind nor drought nor temperatures below -7 °C and requires cool, rich, well-drained soil. Hard to find in nurseries, excellent specimens are found in collections such as at the Brest Botanical Conservatory, sheltered by a cliff at the bottom of a moist valley. Other, less delicate cypress species likely remain to be discovered and trialled in our gardens.

Cupressus sempervirens – botanical illustration

Cypresses most often have a bushy or tree-like, conical habit with heights varying between 5 and 40 m (25 m in cultivation). Habit spreads with age, notably in Lambert cypress (Cupressus macrocarpa) which has a wide trunk and sturdy horizontal scaffold branches. A weeping cultivar exists: Cupressus macrocarpa ‘Pendula’. Mediterranean cypress and the fastigiate form of blue cypress Cupressus arizonica Fastigiata are exceptions with a spindle habit, able to reach between 12 and 45 m tall with a trunk diameter ranging from 1.50 to 3 m at age 10 years. Nevertheless, C. sempervirens includes pyramidal forms with clearly horizontal branches. Grey to purplish-brown bark often bears resin exudations and becomes scaly (C. arizonica) or furrowed (C. sempervirens) with age depending on species. Longevity of cypresses often spans several centuries (500 years for Cupressus sempervirens) and up to 2000 years for Tassili cypress (Cupressus dupreziana), a Saharan species now endangered.

Young leaves take the form of non-prickly needles (unlike those of Juniperus), quickly evolving into triangular scale leaves of 2 to 6 mm arranged in opposite decussate pairs (perpendicular from one node to the next) covering the entirety of very finely ramified shoots. Twigs are cylindrical in contrast to those of Thujas which are flattened. Colour ranges from very dark green to bright green, passing through golden in C. macrocarpa ‘Goldcrest’ or grey-blue in C. arizonica. Species with leaves covered in small glands filled with essential oil are very fragrant.

Male and female flowers appear on the same individual but are separate. Small yellowish male aments of ovoid shape arranged on short shoots shed their pollen between February and May, sometimes causing allergies in sensitive people. Cones, almost spherical, called strobili or galbulus, 15 to 40 mm in diameter, present 6 to 14 imbricate woody scales with a fused bract. Scales open at ripeness after 18 to 24 months, releasing 6 to 20 seeds of 4 to 7 mm long, compared with 2 to 5 in false cypresses (Chamaecyparis), surrounded by a narrow wing.

Large numbers of cones produced are a drawback for Mediterranean cypress whose upright branches arch under their weight and spoil the slender habit. Choosing less fertile cultivars or a spring pruning remedies this defect.

Wood of Mediterranean cypress (sempervirens) is highly prized for its hardness, durability and scent. Blue cypress (Cupressus arizonica) is also grown for its wood or used as a Christmas tree.

Several forms: Cupressus sempervirens / Cupressus macrocarpa / Cupressus cashmeriana

Main varieties of Cupressus (cypresses)

Cupressus sempervirens Totem - Florence Cypress

Cypress with a particularly narrow columnar habit and rapid growth in its early years. It never fruits, which allows it to retain permanently compact foliage and an impeccable silhouette, evoking a tall dark-green totem. This variety is perfect for punctuating an entrance or structuring a garden.

• Height at maturity 12 m

See the product sheet

Cupressus sempervirens var. stricta

Large evergreen conifer with dark-green foliage, very similar to the iconic wild cypress of Tuscany, developing erect branches that give it a tighter habit in a narrow, tall column. Rapid growth in its early years; can live for a very long time and exceed 14 m in height.

• Height at maturity 14 m

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Cupressus macrocarpa

Majestic conifer forming a fine column in youth, evolving towards a wide, spectacular flat-topped crown with dense, deep-green foliage. Native to Monterey on the central Californian coast, it clearly favours the mild, moist conditions of oceanic climates. Its rapid growth, tall stature and elegant silhouette make it a striking presence in a large garden.

• Height at maturity 12 m

See the product sheet

Planting

Where to plant cypress?

Cypresses are not demanding about soil quality, whether poor, rich, acidic, neutral or calcareous provided it is well drained. The hardiness of the main cultivated species is around -15°C so you can plant them as far as Paris region without problem. They tolerate sea spray, wind and heat very well thanks to their deep taproot root system capable of drawing water from great depth. However Monterey cypress clearly prefers the cool, moist conditions of oceanic climates while Arizona cypress and Provence cypress enjoy the warmth of Mediterranean climate. The latter was formerly used as an effective windbreak around fields in Rhône valley until it was decimated by cortical canker and replaced by poplar.

Except for Provence cypress or fastigiate forms, these are trees best reserved for large gardens or for areas set away from dwellings because they quickly occupy a wide space (10 m for Lambert’s cypress), have dense foliage that casts heavy shade and are not easy to fell.

Choose a very sunny position, although partial shade is tolerated, and ensure it is sheltered from cold winds except in southern regions.

When to plant?

Plant cypresses preferably in spring from March to May, especially if winters are cold, or from September to November.

How to plant?

This plant is easy to grow if care is taken to water it well to ensure establishment.

• Plunge the bucket into a bucket of water to thoroughly moisten it.
• Dig a hole three times wider than the rootball and loosen soil around with the tines of a fork-spade.
• Add a few handfuls of sand and gravel to ensure good drainage around the roots.
• Apply well-rotted manure or compost if soil is sandy.
• Place the plant in the planting hole.
• Insert 1 to 3 stakes outside the rootball, especially if specimen is already sizeable, then attach soft ties.
• Replace soil and firm lightly.
• Water

Cupressus macrocarpa and its characteristic cones

Pruning, care and diseases

• Water deeply and thoroughly during first two summers.
• Cypresses tolerate light pruning but are prone, especially in southern regions, to cortical canker, a disease caused by the fungus Seiridium or Coryneum cardinale, present worldwide except in Asia. It appears from spring as dieback of young shoots directly attached to the trunk and then on large branches, together with resin exudations leading to tree death. Wounds and repeated pruning favour contamination as well as attack of the wood by bark beetles. Apply copper preventatively or choose resistant forms such as Italian cypress Mistral or SancoRey. Cypresses do not resprout on old wood or from the stump.
• Mites, aphids and scale insects are also common pests in hot, dry weather but are not very damaging; they can be controlled by spraying with a jet of water or by applying an insecticidal treatment.

→ Learn more about cypress diseases and pests in our advice sheet.

Propagation

Multiplication is most often by sowing in spring or summer after stratifying seeds for at least 3 months. Cultivars multiply fairly easily by propagation by cuttings from August to October.

Sowing

Sow on a heated bed in a well-drained substrate. Lift natural seedlings you can find around shrub varieties in particular.

Propagation by cuttings

Prepare a deep pot by filling it with potting compost mixed with sand, then :

1. Take shoot tips with a heel 12-15 cm long.
2. Remove leaves located near the base of the cutting.
3. Insert these to two-thirds of their length, ensuring they do not touch one another.
4. Firm the compost gently all around to eliminate air pockets.
5. Place them covered in semi-shade, for example by placing a cut transparent plastic bottle over them.
6. In spring, separate rooted cuttings and pot them up, keeping them in pots until planting out in autumn or the following year.→ Discover our tutorial: How to propagate conifers?

Uses and companion plants

Large cypresses are generally used as solitary specimens or in small groups as landscape markers at house entrances, for example. Use as a free hedge to form a windbreak is also common in the south to combat tramontane or mistral. It is not unusual to see hedges of Cupressus sempervirens made up of various clones more or less spreading such as MISTRAL® Agrimed 1 and Antain, which thus provide better protection against wind penetration. These two clones grafted onto sowings of the type species therefore offer reduced sensitivity to cortical canker.

Two examples of use: Cupressus sempervirens ‘Totem’ gives verticality to the garden / Cupressus sempervirens can be pruned into topiary

Cypresses are inseparable from Mediterranean cemeteries, much like yew on the Atlantic coast. Rows of cypresses with very dark foliage are also highly attractive when alternated with olive trees with silvery foliage to emphasise an avenue leading to an estate.

Whether forming a spindle or a cone, blue cypresses and Italian cypresses are sometimes used in topiary, pruned in spiralled shapes, or trained to form pom-poms. These are light pruning operations intended to reduce the length of shoots without cutting into old wood.

Cypresses are useful for repopulating forests on dry soils, for holding soil on gravelly ground, and are considered, for example, for revegetating the Esterel — as with the Tassili cypress, which unfortunately has great difficulty reproducing in its habitat, Sahara, due to lack of water at the time of seed germination.