Conifers for all tastes and all seasons

Conifers are precious trees in the garden because they keep their foliage in all seasons. Resistant, as beautiful in isolated subjects as in hedges, they are part of the fundamentals in a garden.

A wide variety of shapes, a wide range of colors and hardiness are all part of the conifer program!

What is a conifer?

Unlike most trees which are angiosperms, conifers are gymnosperms, which means that they generally produce their seeds (naked ovules) on the scales of their cones. They do not flower in the usual sense of the term. Most conifers keep their foliage in winter (except for ginkgo and larch), which is an important asset in the garden, especially in the case of windbreaks or privacy hedges that must also be effective during the bad season. The tough leaves are often needle-like or scale-like, which gives them a very good resistance to climatic elements, such as heat or cold. The foliage is also less sensitive to evaporation thanks to this constitution.

Conifers for all tastes

In addition to the cedar well known for its rapid growth and its use in hedges for decades, the world of conifers offers an amazing variety that is interesting to exploit in a garden. There are conifers for all tastes and for all gardens, from the largest to the smallest, thanks to the dwarf and creeping varieties.

Sequoias are best reserved for large gardens with their 100 meter height and their consequent spread, as is the Cedar of Lebanon, ideal as an isolated subject on a lawn in mountainous areas which it particularly likes. Whether it comes from Lebanon, the Himalayas or the Atlas, the cedar is always a majestic tree requiring space because it can reach up to 50 meters in height! In terms of colors, the cedar covers a palette ranging from dark green to blue.

The common yew is very interesting in hedges and topiary because it supports well the pruning. Its growth is slow, so pruning operations to obtain a beautiful hedge are limited compared to other trees.

Beware, the foliage and berries are toxic.

Cypress comes in 24 species, the most famous of which is Cupressus sempervirens, the Italian cypress with its characteristic silhouette reaching for the sky. Rustic, ornamental, resistant to pollution, heat and drought, the cypress has enormous assets. It will be used to mark the entrance of a property as a sign of welcome, but also to make graphic alignments marking the contours of a driveway. This cypress can also be used as a hedge.

Among the best known and most widespread conifers are of course the pines. A vast family of about a hundred species, including the umbrella pine with its characteristic silhouette reminiscent of the seashore and sandy soil that it loves, but also the Scots pine, which is more fond of freshness, as well as the Austrian black pine, which is well suited to high altitudes to form vast forests.

We don't think much about juniper in the garden and yet it has many assets. Its bark is decorative and aromatic, its bluish foliage and its berries are all ornamental values. Hardy, it also tolerates drought, heat and sea spray. It grows in all types of soil, even sandy! Among the many species you will certainly find the one that suits you. The creeping forms will be able to cover an embankment, the tortuous forms will be appropriate perfectly in isolated subject, whereas the species with prickly foliage will constitute defensive hedges!

The yew in the garden

The yew is a very popular tree in the garden where it has multiple ornamental functions. Easy to grow and maintain, its many varieties, of various sizes, colors and shapes, can create beautiful atmospheres.

The yew, a tree with exceptional longevity

The yew is a coniferous tree native to the northern hemisphere; the two most cultivated species in the garden are Taxus baccata and Taxus cuspidata.

This evergreen tree made of needles can reach a height of 20 meters and live more than a thousand years. All the parts of the plant are very toxic by ingestion, that's why it has been used for all times for hunting (on arrows) but also as poison by the Romans who got rid of their enemies.

In the garden, it appreciates all types of soil, whether chalky or acid, poor or fertile. However, the soil must remain slightly cool but never soggy. The yew can be pruned very well, which is why it is one of the most appreciated trees in topiary.

Uses of yew in the garden

Yew comes in species and varieties ranging in size from 60 cm to 15 m high. Some adopt a fastigiate habit ideal for verticality, others a compact and spreading habit, perfect for ground cover.

Taxus baccata 'Fastigiata', erect and with a strong development, will find its place on both sides of an entrance of property or in alignment to underline a vast path. Its narrow pyramid shape, reaching for the sky, can also adorn a lawn or serve as a sentinel near a home.

As an isolated subject, this yew catches the eye, it serves as a focal point in perspectives, in which case it can take on the shape of a cone once pruned or retain its natural fastigiated habit.

The non-fastigiated varieties of Taxus baccata are of course widely used to form dense hedges as is Taxus x media. The latter is faster growing and has a compact habit, although it can still reach 5 m in height. Very durable, this evergreen hedge will only need one annual pruning, which is an advantage compared to other species that grow much faster.

In Zen gardens or gardens with a Japanese tendency, Taxus cuspidata with its well-structured branches and evenly distributed needles is a subject of choice. Trimmed 'in the cloud' it always looks good surrounded by Japanese maples, camellias and ferns. This species, if planted in semi-shade, tolerates drought well.

To cover an embankment, adorn a riprap, or simply cover an area where grass is not growing, consider Taxus baccata 'Rependans' a ground cover variety that doesn't exceed 60 cm in height but spreads to nearly 5 m. Over time, or with a little help from precise pruning, it forms very attractive rounded cushions. The variety 'Summergold' with its very luminous golden yellow foliage can be used for the same purpose.

The yew can also find its place in beds, depending on the variety, it will then be planted in the background of the decor in the company of shrubs, or in the center to create a contrast with flowering plants.

The yew also invites itself on the terrace in pots or large containers. Once again, the 'cloud' shapes will have the best effect, but don't neglect the compact varieties that can easily replace boxwood and be cut into a cone or ball for a very classic look.

The Conifers

The vast world of conifers offers a wide range of possibilities in the garden. Slender, pyramidal or drooping, the silhouettes of these trees are always elegant. The choice is yours!

How to choose your conifer?

Conifers generally become large trees, most of them imposing and very decorative. Except for the ginkgo or the bald cypress, they have the advantage of not losing their leaves and therefore remain green all year long.

Very hardy, they adapt to most gardens, even in the mountains for most of them. Some of them, such as the lariccio pine, the Atlas cedar or the Nordmann fir, are recommended in places where the elements are unleashed in winter and where the cold reigns. Others particularly appreciate sandy soils and tolerate sea spray and drought, such as the umbrella pine, which is very well adapted to the seaside, majestic in its bearing and producing delicious pine nuts, or the Florence cypress, which once well established, will launch its arrow towards the sky despite poor soil and drought.

If your garden is crossed by a stream or borders a marshy area, think of the magnificent Bald Cypress which will adorn the banks with its drooping and tortuous branches. Reserve a nice space for it, as this tree can reach 30 m in height for a spread of 20 m. In cool and chalky soil, think of the yew to decorate a shady area.

If your garden is very large and you wish to create an imposing alignment, don't hesitate to use the sequoia, a tree with an erect bearing and a narrow crown that can reach 60 m in height. It needs deep, rich, acidic soil to do its best.

As isolated specimens on a lawn, the large Atlas or Lebanese cedars always do wonderfully with their imposing port shaped by the elements. Again, allow for space as these majestic trees can grow to impressive sizes.

Conifers are also ideal for forming compact hedges, windbreaks and privacy screens. Choose the Leyland or Florence cypress that you can prune to contain their vigorous growth.

Let's not forget the ginkgo, a conifer that is a bit special since it does not have needles or scales but rather curiously cut leaves, very original, green then turning golden yellow in autumn. Very ornamental, it deserves a place of choice in a patio or on a lawn, but also finds its place in a Japanese or Zen garden.

How to plant your conifers?

A fall planting in September or October, when the ground is still warm but the rain is abundant, is recommended.

Always ask about the adult size of your conifer, because as we have seen, some of them can reach 60 m in height and a spread of 20 m. Do not consider such a tree if your garden is small and respect the planting distances and the regulations concerning the plantations on property lines.

Prepare the planting hole a month in advance. If your plants arrive sooner than expected, don't panic! They can survive in their containers until your land is ready for them.

Add compost and ground horn to the planting hole.

Soak the root ball to hydrate it before planting, then carefully remove the pot, keeping the root ball whole and not disturbing the roots (no pruning or pruning).

Install your tree in the planting hole, fill in, pack and water very abundantly.

Leave a basin around the foot to contain the water.

Blue trees, a strong personality

"Real" and "fake" blue trees come in a large number of cultivars, more or less dwarf, which can be recommended for a small garden.

The dwarf Colorado spruce, Picea pungens 'Glauca Globosa' is commonly called the "dwarf blue fir". It is the most common cultivar, and certainly one of the best varieties for small gardens and container growing. It forms a nice compact ball, which evolves into a rounded pyramid that can reach 2 m high at 30 years. The average annual growth is 6 to 8 cm. The short and tight needles, prickly, keep a beautiful silver-blue color all year long. It has been cultivated since 1937.

Among the Picea pungens, there are other dwarf forms like 'Glauca Procumbens', totally spread out, to be cultivated with golden heather. It has been cultivated since 1910.

Picea pungens 'Prostrata' is a closely related cultivar that does not exceed 60 cm in height, but can spread over 2 m wide.

The white fir (Picea glauca) has given some dwarf and bluish forms like: Picea glauca 'Echniformis' which forms a spreading cousin of 50 cm high at adulthood, with greyish glaucous green needles. Picea glauca 'Sanders Blue' forms a cone of about 50 cm high at 15 years old, with very nice young blue shoots.

Collectors will remember some less common forms like Picea x mariorika 'Machala', a hybrid of Picea mariana and Picea omorika, which forms a compact rounded pyramid with a silvery blue sheen. It reaches barely 1 m in height and width when mature. It can be recognized by the two silvery white stripes on the back of its needles (like Picea omorika).

Among the true firs, the dwarf and blue forms are rarer.

Abies concolor 'Archer's Dwarf' is a slow-growing, glaucous American cultivar to be grown in rock gardens.

Abies concolor 'Compacta' with greyish steel blue needles is more common, characterized by an irregular silhouette. It can grow to over 2 m when fully grown. It has been cultivated since 1891.

Abies cephalonica 'Meyer's Dwarf' (or 'nana') grows horizontally. It is cultivated since 1963.

Abies lasiocarpa 'Compacta' (sometimes wrongly called Abies arizonica 'Compacta') forms a nice regular pyramid, very tight, of a beautiful bluish grey. It is over 2 m high when mature and resists well to drought, but does not appreciate limestone. It has been cultivated since 1927.

Abies magnifica 'Nana' is a rarity that forms an irregular stack of bluish swatches.

Abies pinsapo 'Horstmann Witches', takes a spreading, rather irregular form with a mixture of green and bluish branches.

Abies procera 'Blaue Hexe' is a very dwarf, tightly balled form from Germany, best grown in pots.

Small blue conifers - Family portrait

There is an impressive quantity of conifer cultivars with more or less blue foliage. Here is a selection of the best forms that are offered by nurserymen.

Cedars (Cedrus)

Dwarf forms are quite rare in this category of conifers and always very original. The Himalayan cedar (Cedrus deodara) has a dwarf form with silvery blue foliage, 'Feeling Blue'. It is a slow-growing creeping cedar, ideal for planting in containers or rock gardens, or even to cover the ridge of a low wall. Adult height 80 cm, width 3m.

Spruces (Picea)

This category includes conifers with a really intense blue color.

The dwarf Colorado spruce, Picea pungens 'Glauca Globosa' is commonly called "dwarf blue fir". It is the most common cultivar, and one of the best varieties for small gardens and container growing. It forms a nice compact ball, which evolves into a rounded pyramid that can reach 2 m high at 30 years. The average annual growth is 6 to 8 cm. The short and tight needles, prickly, keep a beautiful silver-blue color all year long.

Among the Picea pungens, there are other dwarf forms such as 'Glauca Procumbens', totally spread out, to be grown with golden heather. 'Prostrata' is a closely related cultivar that does not exceed 60 cm in height, but can spread over 2 m wide.

The white fir (Picea glauca) has given some dwarf and bluish forms like: Picea glauca 'Echiniformis', which forms a spreading cousin of 50 cm high at adulthood, with needles of a greyish glaucous green. Picea glauca 'Sanders Blue' forms a cone about 50 cm high at 15 years old, with very pretty blue young shoots.

False cypress (Chamaecyparis)

Blue forms are rarer in the dwarf than in the taller varieties.

Chamaecyparis pisifera 'Boulevard' forms a compact pyramid with silvery-blue young foliage, reaching 3 m high in 15 years. This conifer grows very well in a container and can tolerate part shade. 'Squarrosa Lombarts' has very fine foliage, soft to the touch, which turns bluish to purple in autumn. It forms a flattened sphere of 1.50 m high at 20 years.

Juniper (Juniperus)

There are many blue spreading forms among the junipers, many of which have fine needles that are quite prickly.

The common juniper comes in several blue forms, including 'Blue Chip' (or 'Blue Moon'), with a spreading habit, of a steel blue that turns purplish purple in winter, it does not exceed 30 cm in height, for 1 m wide; and 'Wiltonnii', totally prostrate, of a pretty steel blue with very fine foliage, which turns purplish in winter. It spreads over 2 m. These are very resistant conifers that can withstand both cold and heat.

The Chinese juniper (Juniperus chinensis) has a very beautiful glaucous blue cultivar, 'Blue Alps', which forms a bushy erect bush of irregular appearance.

The scaly juniper (Juniperus squamata) in its 'Blue Carpet' form is very prostrate, with short shoots of bright silvery blue foliage. Perfectly hardy, it can be pruned. It does not exceed 50 cm in height, but spreads over 1.50 m. 'Blue Star' is more compact, in the shape of a spiky ball of a very bright blue. It tolerates limestone, but grows very slowly, which makes it recommended for pots. Maximum height: 1 m. 'Meyeri' has obliquely spreading branches of a steel blue that turn purple in winter. It can reach 2.50 m high, doing well in limestone soil.

The beach juniper (Juniperus conferta), exists in a form with blue-gray foliage 'Blue Pacific', a creeping conifer whose branches lie on the ground, or fall down in cascade when it is cultivated in pot. It tolerates drought and calcareous soils. Its color is more intense in the sun.

The sabina juniper (Juniperus sabina) is naturally glaucous, a color accentuated in the cultivar 'Blue Danube', a plant with a very spread out habit, whose foliage has bluish gray reflections.

Firs (Abies)

Dwarf and blue forms are quite rare in the genus Abies.

The Colorado Blue Fir (Abies concolor) has bluish-green needles. 'Archer's Dwarf' is an American cultivar with glaucous foliage and slow growth, to be grown in rock gardens. Compacta', with greyish steel blue needles is more common, characterized by an irregular silhouette. It can grow to over 2 m in height.

The Greek fir (Abies cephalonica) has produced some slightly bluish cultivars. Meyer's Dwarf' (or 'Nana') grows horizontally.

The mountain fir (Abies lasiocarpa) produces a dwarf form of a superb bluish-gray 'Compacta' (sometimes wrongly called Abies arizonica 'Compacta') which forms a nice regular pyramid, very tightly packed. This cultivar grows to over 2 m tall as a mature tree and is drought resistant, but does not appreciate limestone.

The California red fir (Abies magnifica) has a rare 'Nana' form, which consists of an irregular stack of bluish swatches.

Spanish fir (Abies pinsapo) mixes green and bluish twigs in the cultivar 'Horstmann Witches', which takes a spreading, rather irregular form.

The noble fir (Abies procera) exists in a very dwarf form 'Blaue Hexe', a compact ball, native to Germany, to be grown mostly in pots.

Blue conifer FAQ

How to avoid sudden browning?

When it occurs in hot, dry weather, this phenomenon is due to an attack of red spiders. This is the number one enemy of blue conifers. A systematic preventive treatment with a specific acaricide (based on dicofol or cyhexatin) is recommended, as soon as the climatic conditions are favorable to the development of mites.

In cool and rainy weather, it is more likely to be conifer dieback (Phytophthora cinnamomi). This rapidly fatal disease is more frequent in containers. It affects young plants more strongly. Aliette is the only effective preventive product against this fungus that develops in the soil.

Why is a green branch growing on my blue conifer?

This is a phenomenon of reversion that is frequently observed in plants with colored or variegated foliage, but also in double flowers, which become single again. It is simply a return to the original type. You should remove the green part very quickly, as it always has a higher vigor than the colored shoots. In grafted trees, the rootstock can also be freed, with the emission of vigorous shoots (gourmands).

Are blue conifers resistant to cold?

Yes, they are. Frosts of -10°C and even -15°C have no effect on these plants. However, young trees should not be exposed to cold winds for the first five years after planting. A mulch of pine bark will also play a protective role for the roots against heavy frosts, especially for plants in containers.

The garden of the curious and the botanist

• Picea pungens was discovered in Colorado in 1862 by Dr. C. Parry. It is the cultivar 'Glauca Koster', obtained in 1885 by the Dutchman Arie Koster, which is today the most popular blue fir. It reaches 15 m in height.
• The true name of "blue fir" should be reserved for Abies procera, also called "noble fir", native to the mountains of Oregon, where it was discovered in 1825 by David Douglas
• Permanent mulching with light blonde flax chaff highlights the blue foliage of the conifer, while reducing watering and weed growth.
• The somewhat unchanging appearance of evergreens can become monotonous if they are too dominant in the garden. Do not exceed 50% conifers in the composition of a bed, the reasonable proportion being rather one third.
• Many blue conifers (especially in dwarf forms) are propagated by grafting. This, together with their slow growth, explains and justifies their relatively high price.
• The needles of conifers that fall as the foliage regenerates, acidify the soil. It is therefore advisable to lime (a handful of slaked lime per square meter) every two years or so.

What to plant under a conifer?

In the forest as well as in the garden, it is rare to be able to appreciate the spectacle of exuberant vegetation under a conifer. However, by using a few tricks and appropriate plants you can decorate its foot in the most beautiful way!

Problems to overcome

Under a conifer, several parameters come into play, reducing the chances of spontaneous plant growth.

First of all, the needles of conifers that have fallen to the ground produce toxins that allow them to avoid any competition at their feet by inhibiting the germination of other plant seeds. Nutrients and water are thus reserved for them.

Some conifers, such as umbrella pines for example, have superficial roots that draw nutrients, making the soil very poor on the surface, so plants that would have succeeded in germinating do not find enough food to grow properly.

The sometimes dense shade that conifers produce is not suitable for most plants. Let's add to that a significant lack of water because the rain has a hard time penetrating the branches of these evergreen trees for the most part.

Here is a very worrying picture completed by the acidification of the soil caused by the decomposition of the famous needles preventing the calcicolous plants from settling down durably.

Solutions for planting under a conifer

No need to panic! Once the causes are known, it is always possible to get around them!

• Never sow seeds under a conifer, as we have seen, they will have little chance of germinating. Prefer to install already well-developed seedlings in cups or pots.
• Rake out the needles and replace them with a thick mulch of well-ripened compost to gently fertilize the soil. Work it in with a claw, taking care not to damage the tree's roots.
• When you decide to install a plant under a conifer, create a pocket of potting soil and add a handful of ground horn and dried blood mixture, not forgetting the mycorrhizae that will help your plant build a stronger and more efficient root system by entering into symbiosis with them.
• Choose only shade loving plants and forget about those that need sun to bloom.
• Don't hesitate to install an automatic watering system under your conifers to compensate for the lack of water.

Which plants should be installed under a conifer?

If it's a large tree with a bald trunk, think of the lianas that will climb along it. Clematis is ideal and you will find many varieties. Some ramblers can also be placed at the foot of your conifer, so choose the variety according to your climate and prefer ADR-labeled roses that are much more resistant.

Think also of climbing honeysuckles or the splendid ivy in its variegated versions.

As for ground cover plants, opt for white or blue periwinkle, which are always delicate and form a beautiful carpet!

If you prefer flowering plants, try bergenia, this plant that is so easy to grow that it will cover itself with bouquets of pink flowers without any effort on your part. The same goes for perennial geraniums, very hardy and floriferous, which will grow without any problem under your conifers, as will St. John's wort, which will offer you its golden yellow flowers from June to September.

As for decorative foliage, choose the asarum, whose many cultivars offer silvery shades of the most beautiful effect or for one of the many varieties of Brunneras.

We don't think much about lungwort, these plants with trailing rhizomes, with foliage that is sometimes silver or mottled, and which has beautiful flowers from February to May. Here again, you will have a vast choice among cultivars with a palette ranging from white to red, passing through all shades of blue and purple.

Outdoor evergreen ferns are also a great way to decorate the base of your evergreens with their textured fronds.

Heather plants also thrive in the shade of conifers and in this acidic soil. Plant azaleas in groups, or clumps of rhododendrons and camellias. If you prefer the wild side of heathers, create beautiful carpets with these easy to live with plants.

For a blooming winter, think of the multiple cultivars of hellebores. This plant known as 'Christmas Rose' has beautiful white, green, yellow, pink, red, purple and even black flowers, sometimes variegated or spotted, single or very double. What a great way to start a collection!

If you like surprises, plant bulbs and forget about them! Their blooming will be a renewed wonder every year. Naples cyclamen, wood hyacinths, anemones, snowdrops, muscarias, puschkinias, daffodils, bear's garlic, summer peppermint, botanical tulips, lily of the valley... You'll find plenty to stagger the blooms! Bulbs can also naturalize and form beautiful carpets over time, so take advantage of it!