It is not only their shell-shaped needle nests that make the shell cypress an extremely exquisite plant for stylish front yard plantings or Japanese gardens. Because we are dealing here with a true noble tree that has even made a career in the field of sacred architecture in its homeland.

The shell cypress originally comes from Japan

Table of Contents

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  1. origin
  2. growth
  3. leaves
  4. flowers and fruit
  5. Which location is suitable?
  6. What soil does the plant need?
  7. How do I plant correctly?
  8. Cut clam cypress correctly
  9. bonsai
  10. Propagating clam cypress
  11. Diseases
  12. pests
  13. sorts

    14. origin

    The other common German name of the shell cypress is Hinoki Scheinzypresse - and this name already resonates a lot with its origin. That's right - the Chamaecyparis obtusa, as it is called botanically, comes from Japan, of course. This is suggested not only by their name, which sounds so Far Eastern, but also by their artistic appearance, which is so typical of Japanese garden culture. From a German point of view, the shell cypress was first described by the botanists PF von Siebold and JG Zuccarini in the mid-19th century.

    In its homeland, the mussel cypress has far more than just a decorative garden ornament use. Rather, it is also used for economic purposes because of its many other positive properties. It contains, for example, valuable essential oils in wood and needles, from which the so-called hinoki oil is extracted. Its light wood, which smells wonderfully lemony, is also used in Japan as a precious raw material for sacred buildings such as temples and palaces, for shrines and also for table tennis bats.

    With us, however, the mussel cypress is mainly only used for ornamental gardens. Above all, the dwarf forms such as the small shell cypress are widespread in this country.

    Origin at a glance:

    • Shell cypress comes from Japan
    • First described by Germans in the mid-19th century
    • Used in Japan not only as ornamental wood, but also as valuable construction wood for sacred buildings
    • Also for obtaining hinoki essential oil
    • With us rather only for garden ornaments, v. a. the dwarf forms

    growth

    The mussel cypress belongs to the cypress family and grows as an evergreen conifer. Its habit is characterized by an expansive columnar shape and an original, somewhat idiosyncratic crown structure due to the somewhat irregular branching. The crown is already on the ground and forms conical, wide shoots. These are flat and fan-shaped, so that the wide, shell-shaped structures that give it their name are formed at the ends.

    Shell cypresses can reach a height of up to 40 meters - the dwarf shell cypresses, which are more common in this country, however, grow to a maximum of 2.50 m in height and around 1.5 m in width. Also, they grow very slowly. The trunk wood is light on the inside and surrounded by a reddish-brown bark.

    Growth characteristics in keywords:

    • Columnar growth
    • A spreading, irregularly structured crown that is set close to the ground
    • Broadly fanned out, flat, evenly shell-shaped shoot ends
    • Growth heights of up to 40 metres, with dwarf species only around 2.50 m in height

    leaves

    The mussel cypress's short needle leaves have a scale-like texture typical of cypresses and attach close to the ends of the shoots. These are spread out like a fan and as if pressed together - this is how the leaf groups form their typical shell-like shape. The color of the leaves is a deep dark green.

    flowers and fruit

    In principle, mussel cypresses naturally form flowers and cones for the purpose of propagation. The cones have a densely scaly, spherical appearance of about 8 to 12 millimeters in diameter and nest-like in the ends of the shoots. However, the garden forms cultivated in this country are sterile - they do not form either flowers or cones.

    Which location is suitable?

    The mussel cypress prefers a semi-shady place. Too much sun can certainly damage it - nevertheless you should make sure that it gets as much light as possible from all sides, otherwise it tends to grow irregularly.

    Of course, this is not so easy, especially in the open air - with a southern orientation, where the conifers are illuminated from the west and east and in the south by trees or similar. is shaded, but it can succeed well. With bucket culture, the risk of tail growth can of course be easily dealt with by turning.

    The shell cypress should not be placed in a rock garden - even if its Japanese appearance would look good in a Far Eastern designed gravel bed. She doesn't like the dryness and the high heat radiation of the stony bed surface at all.

    Location requirements in brief:

    • Rather semi-shady, not too intensely sunny - risk of drought damage
    • Pay attention to even light from all sides to prevent crooked growth
    • Location in the rock garden not recommended

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    What soil does the plant need?

    The mussel cypress requires a permeable, fresh, moist and relatively humus-rich plant substrate. The pH value should be in the rather low, i.e. low-lime, range. If you plant the mussel cypress outdoors and find a rather loamy, heavy soil at the planned location, you should loosen and improve it with sand and leaf compost. A drainage layer made of gravel is certainly not wrong either.

    For the substrate in the bucket, you should use high-quality, nutrient-rich potting soil, which you loosen up with a proportion of sand or coconut fibers and a little lava grit. The mussel cypress in the pot is also happy about a permanent supply of nutrients with compost.

    Earth claims at a glance:

    • Permeable, humus, fresh and moist
    • pH value rather low
    • Loosen and enhance heavy soil outdoors with sand and leaf compost, gravel drainage layer
    • In the pot: good, nutrient-rich potting soil with some compost and sand

    How do I plant correctly?

    Very few garden plants like to be transplanted, especially if they are cultivated outdoors. Shell cypresses are no exception. Although they are very robust overall, they do not easily gain a foothold in a new location due to their slow growth. However, if you absolutely want to implement them, proceed as follows:

    You should choose autumn as the time when the conifers have finished their main vegetation phase, but there are not yet any severe frosts. Dig out the root ball as generously and carefully as possible and place the tree in the new planting hole, which you have provided with a base bed made of a gravel drainage layer and sandy compost. Then fill the hole with humus-rich soil and tread firmly all around and water vigorously. A layer of mulch on top of the planting area is recommended to protect the stressed root system from cold damage and drying out.

    Refrain from pruning to compensate for the inevitable damage to the roots. In the case of the slow-growing conifer, this is more debilitating than strengthening.
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    Cut clam cypress correctly

    In principle, topiary care is not necessary for the dwarf mussel cypresses cultivated in this country. They grow very slowly anyway and develop their characteristic structure best when left alone. Above all, radical pruning is not advisable for the conifer species, as it does not sprout again from cuts in the old wood. Younger specimens can still be shortened slightly on the outside in spring if their shape does not develop as you would like. However, never cut back more than about 3 cm.
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    bonsai

    Nevertheless, mini shell cypresses, like many other cypress species, are also suitable for bonsai culture in the garden. Especially in a front yard, an artistically shaped shell cypress can be very decorative. For the design, it is particularly recommended to work with accurate foliage cuttings. Strictly and regularly wired branches come into their own when the shapely needles stand in precisely contoured bushes at the ends of the branches.

    When wiring the trunk and branches, make sure to remove the wires from May, when growth in thickness begins. In this way you avoid traces of wiring or ingrowths. You should fertilize a bonsai mussel cypress regularly during the growth phase.
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    Propagating clam cypress

    Propagating a mussel cypress is not entirely trivial. Due to its generally so slow growth, it is not so easy to grow in vegetative propagation. Nevertheless, the cuttings method is actually the only method of choice for private gardeners. You won't get seeds from the sterile garden forms anyway.

    You generally have a higher chance of growth with younger mother plants that are still full of juice. With older specimens it can be very complicated. In late summer, use an angled cut to cut a shoot that is about 15 centimeters long and that is as fresh as possible from the upper part of the crown. Defoliate except for a top pair of leaves. It is strongly recommended to dip the cut surface in rooting powder.

    Place the cuttings prepared in this way in a planting bowl with humus-rich potting soil. The chances of growth are highest if you have a (mini) greenhouse available in which you can provide the cuttings with an evenly warm, humid and protected climate. It should get plenty of light, but be protected from direct sunlight.

    If the cutting forms new shoots, you - or he has - made it and has grown. Continue cultivating it indoors or in the greenhouse over the winter. The young mussel cypress should only be planted outdoors after its first year of life.
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    Diseases

    The mussel cypress is very sensitive to waterlogging. If your planting ground is not permeable and humic enough, it can be attacked by the Phytpphtora cinnamomi fungus, which causes the roots to rot and the plant to die. When planting, be sure to ensure adequate drainage and good loosening of heavy soil with coarse-grained sand.

    The mussel cypress can also be afflicted by the shoot dieback that often occurs in conifers. You can recognize this disease by dying shoots and black dots on the affected areas. However, shoot death can be easily controlled with a fungicide.
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    pests

    The mussel cypress can occasionally be attacked by scale insects or spider mites.

    scale insects

    You can recognize scale insects, among other things, by the honeydew that they secrete when sucking on the juicy shoots of the mussel cypress. If you are not careful, sooty mold fungi can nest under the honeydew.

    If the scale insect infestation is still relatively weak, attack the insects mechanically by removing them from the plant with a damp cloth or toothbrush. You can then treat the mussel cypress with a decoction of nettles or tansy. For more advanced infestations, use oil-based preparations that suffocate the lice.

    spider mites

    These parasites are actually primarily houseplant pests. But they don't stop at the tasty shoots of mussel cypresses either. They give themselves away easily by the fine webs with which they cover the branches and leaves of the host plant. With a structurally robust plant like the mussel cypress, you can work with a strong jet of water from the garden hose. Rinse them thoroughly, several times if necessary. This should normally get the infestation under control.

    If the population is too stubborn, you may have to cut off the affected parts of the plant and dispose of them as thoroughly as possible, preferably by burning them. The use of predatory mites, for example in the form of the gall midge Feltiella acarisuga, is particularly ecologically sensible. However, they can only be used for planted mussel cypresses in summer when temperatures are above 20°C. Only then do the beneficial insects have suitable living conditions. In addition, there should be high humidity.

    sorts

    The dwarf variety 'Nana Gracilis' is the most common in specialist shops. But there are also a few other cultivated forms, which differ from each other mainly in their foliage color and partly also in their growth habit.

    Chamaecyparis obtusa 'Nana Gracilis'

    In German, the variety is simply called Zwer-Muschelcypress. Its growth is indeed dwarf - it reaches a maximum height of 3 meters and a width of about 2 meters. It shows a compact, well-branched, initially spherical and later more conical growth. The horizontally protruding branches form dense coniferous bushes. The variety is also well suited for grave planting due to its compact, tidy appearance.

    Chamaecyparis obtusa 'Lycopodioides'

    This variety is also called coral false cypress in German. This designation already indicates its peculiarity: In fact, it develops coral-shaped, twisted shoots, which give it a much more filigree appearance overall than most of its conspecifics. Their needle color is a cool blue-green. In terms of height and width, it grows to about the same size as the Nana Gracilis variety.

    Chamaecyparis obtusa 'Remote Spray Gold'

    The name says it all for this variety as well: It is characterized by a golden yellow needle color, which gives it a fresh, delicate character. Its growth is also unusual: It forms gently curved branches that extend from the ground and have tapering tips and fine needles. This makes it look like a fern. Fernspray Gold is very slow growing.

    Chamaecyparis obtusa 'Aurora'

    The Aurora variety is also characterized by yellowish coniferous leaves and can therefore set a particularly attractive color accent, especially in combination with dark-leaved coniferous trees. As with the Nana Gracilis, it grows quite bushy and compact, but becomes significantly smaller with a maximum height of one meter. In width it reaches about 60 cm.

    Chamaecyparis obtusa 'Pygmaea'

    This variety shows a rather spherical habit and, at around 3.50 meters in height, is slightly larger than the other dwarf varieties. Its coniferous foliage has a fresh green color that turns brownish in autumn.

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