Proper planting distances for trees and shrubs

We rarely ask ourselves the question of the development of a plant when it is planted. Whether planted alone near a building or in a hedge, trees and shrubs must have enough space to grow and not cause any damage.

Trees with large development

Would you like to adorn the front of that old wall with the silhouette of a majestic tree? Be careful, some species will undoubtedly lend themselves to this, but others should be avoided. Let's take the simple image of an iceberg: the emerged surface represents only a part of the existing... For trees it is the same thing! Some of them develop a root system so important that it represents twice the volume of the foliage!

Generally speaking, plan to plant large trees such as oaks, plane trees, pines or cedars at a minimum distance of 10 meters from any concrete construction. Only trellised pear or apple trees and, of course, climbing plants will be able to adorn your old wall in complete safety.

Similarly, certain trees that produce suckers should be avoided near buildings, such as mahonia, locust trees or even certain poplars whose roots can slip under the structures.

Let's not forget either that a large tree weakened by a storm can become dangerous and that falling branches are not rare. Some trees are more susceptible than others. So never plant a walnut, a poplar, a eucalyptus or an ash tree, not far from a veranda or a roof.

The same goes for drains and septic tanks, which should always be kept away from future plantings because the roots looking for water could very well make them explode.

Medium-sized trees

The planting distance will be a little shorter for medium-sized trees such as the plane tree, the hornbeam or the Judas tree. For these plants, leave a space of 5 meters from a building. Beware of the fig tree, which under its harmless appearance, has intrusive roots that play on any masonry element with disconcerting efficiency.

Don't imagine that you can stop tree roots with anti-rhizome barriers like those used to control bamboo! Much deeper and more intrusive, tree roots will be totally insensitive to them. It is therefore better to respect the right distances.

Ornamental shrubs

Forsythia, lilac, seringat, buddleia and other weigleias are very appreciated for their decorative flowers. For them to grow well, leave a distance of 1.20m on all sides around the shrub so that it can benefit from both the light and the ventilation necessary for its good health. In beds, bush roses should be spaced 80 cm apart.

The heathers

The heathers of the genus Erica

The heathers of the genus Erica are :

• winter flowering heathers, such as Erica x darleyensis and Erica carnea ;
• summer flowering heathers with, for example, Erica vagans or Erica cinerea;
• shrubby heathers with Erica arborea, Erica Erigena (this is a heather that is not very common in gardens but which can grow up to 60 cm and flowers from autumn to winter) and Erica scoparia (the broom heather), including Erica scoparia ssp Azorica, with its luminous green foliage and spiral shape.
• The heathers of the genus Calluna
• The genus Calluna includes mainly summer flowering heathers with different colors of foliage and flowers. The height of the callunas is variable; while some reach 50 cm high, others, carpeting, do not exceed 15 cm.

The heathers of the genus Daboecia

The leafy heathers belong to the genus Daboecia. Daboecia x scotica 'Silverwells' is a small heather (15 cm) very floriferous which forms very big white bell-shaped flowers.

Cultivation needs of heathers

Generally, the heathers are happy in a peaty, light, fresh soil, with a rather acidic pH (around 6,5). However, Erica cinerea behaves as well in sandy soil, a little drier, just like the broom heather.

The maintenance of the heathers is simple: an annual pruning is carried out during the first two weeks of April. The heathers of the Calluna genus are simply cut back, under the flowering.

The multiplication of heathers

The heathers multiply by cuttings or by sowing.

Erica carnea multiplies naturally thanks to its horizontal branches which marcott when they develop on a light soil.

Companion plants for heathers

To accompany heathers in the garden, choose shrubs with spring flowers or colored foliage, such as Diervilla x splendens, a shrub with red autumn foliage, very resistant and which supports all exposures and all soils. It tends to form a clump that is wider (3 meters) than tall (2 meters). Planted in a group and accompanied in front by tree heathers, you will obtain a nice bed.

The camellias

The camellia, which is a shrub that can reach 5 to 6 meters in height, is rather a plant of undergrowth, which appreciates semi-shaded situations.

There are many species, the best known of which is Camellia japonica. Camellia sasanqua, Camellia x williamsii, Camellia reticulata and all the hybrids from these four original species arrived after the war.

Some varieties of camellias

Among the Camellia japonica :

• Camellia japonica 'Adolphe Audusson', the most widespread of the French camellias. The example shown is a stemmed camellia, but most camellias are shrubby, with branches present from the base of the trunk.
• Camellia japonica 'Abbé de Beaumont', a very old variety with large late pink flowers.
• Among the hybrids :
• Camellia 'Freedom Bell', a very long flowering camellia with a semi-double flower.
• Planting advice
• The camellia is a heathland plant that grows on rather acid soils. In Brittany, where soils are generally acid, fill the first half of the planting hole with original soil, and the second half with a mixture of 1/3 heather soil and 2/3 original soil.
• In rather calcareous grounds, it is necessary to fill the holes of plantation with soil of heather, only.
• The exposure is also an important element to take into account during the plantation. The camellia is a mid-shade plant, so it should be placed if possible in the north, or east, so that it is in the shade in summer and that, in winter, it thaws slowly.

Camellia maintenance

Although it grows slowly, the camellia may need to be pruned after a few years, which it does very well.

However, it is important to be able to prune it before it starts to grow again in spring. If you prune too late, when the vegetation has restarted, the coming flowering will be inhibited.

Camellia diseases and pests

Camellias can be victims of mealy bugs and fumagine. If their presence has an obvious aesthetic impact, it does not affect the health of the camellia.

To eliminate mealy bugs, spray white oil under the leaves; this is where they are found. Take action as soon as you see a little black on the leaves.

Camellia, a plant of patience

The camellia needs a certain number of years of cultivation to reach an interesting volume. A plant that can be found on sale is between 5 and 10 years old, or even more (up to 15 years).

Decorative flowering dogwoods

With these dogwoods we will speak rather of inflorescences than of flowers in the botanical sense of the term because the flowers themselves are insignificant. It is the whole formed by the flowers and the bracts which is ornamental on the dogwoods.

On the dogwoods with decorative flowers, the inflorescences appear in spring or in summer, which allows, by varying the species, to extend the flowering period. All dogwoods then bear fruits that are more or less attractive and sometimes even edible.

• The strawberry dogwood (Cornus capitata) owes its name to its large spherical fruits that look like strawberries in the fall. This bushy shrub can reach a height of 12 m for as much spread, so it is to be reserved for large gardens!

Native to China and the Himalayas, it is covered with creamy white or yellowish bracts in summer.

• The flowering dogwood (Cornus florida) is a shrub that can reach 8 m in height. Its conical habit is one of its assets, completed by its white inflorescences in 'Cherokee Princess' or 'White Cloud', bright pink in 'Cherokee Chief', 'Welchii' or 'Rubra' or yellow in 'Hohman's Gold'. The leaves of this beautiful shrub turn crimson red in the fall, which adds to its charm.
• Cornus Kousa, is not to be outdone in terms of flowering, since this shrub with a conical shape and a cracked trunk is covered with white inflorescences in June on the typical species, but which can be yellowish on 'China girl' or bright pink on the variety 'Satomii'. This species includes many cultivars with variegated foliage, which does not spoil anything!
• Cornus nuttallii also has a conical habit and can reach up to 12 m in height. It is covered with beautiful white inflorescences, sometimes tinged with pink in spring. The variety 'Colrigo Giant' has large creamy white inflorescences resembling buttercup flowers.
• Cornus Porlock is prized for its spreading habit. This imposing tree can reach 10 m in height and 5 m in spread and presents white bracts turning to salmon pink in May.

Planting decorative dogwoods

The planting of flowering dogwoods is a little more delicate than that of other species because some of them require an acid, fertile, humusy and very well drained soil. This is the case of Cornus capitata, Cornus florida and Cornus nuttallii. Beware of Cornus Canadensis which only tolerates very acid and humid soils!

Daphnes, shrubs with an extraordinary fragrance

Varieties of Daphne

Daphnes, most of which come from Asia, are plants known for their extraordinary fragrance.

Among them, we find in particular :

• Daphne odora: the most classic and most fragrant of the daphnes; the one from our grandmothers' gardens. The most sold variety is Daphne odora 'Aureomarginata', with leaves edged with a small yellow border.
• Daphne 'Perfume Princess': a hybrid daphne that appeared a few years ago and is gaining recognition for its larger flowers, longer blooming time and interesting citrus scent. Another advantage is its resistance to sudden dieback.
• Daphne 'Eternal Fragrance' and Daphne 'Pink Fragrance' are English varieties with white flowers for the first one, and with pink-purple flowers for the second one. Their perfume is not comparable to the first two daphnes. On the other hand, their flowering is very long (3 to 4 months, even more) and they are also small shrubs less complicated to grow than Daphne odora.

The culture of Daphne

Daphne are known to be difficult to grow. Even at the nursery, it is sometimes difficult to keep beautiful Daphnes in pots. The problem comes from a fungus present in the soil, belonging to the Phytophthora family which, when a plant is stressed, will be able to penetrate the roots, block the whole vascular system of the plant and prevent the sap from circulating. The affected daphne will wither in two or three days, often at the first heat stroke.

The stress which weakens the plant at the beginning is often due to the excess of water which asphyxiates the roots. Degraded, they then let in the fungi.

To avoid that, it is necessary to cultivate the daphne in a light but rich and fresh soil, of forest type. On clay soil, it is recommended to plant the daphne on a mound, to mulch the soil with an organic mulch (lawn clippings, RCW, straw) to keep it fresh and, when planting, to make good amendments such as compost.

The ideal exposure for daphnes

• In regions with hot summers, prefer half-shade (sun in the morning, shade in the afternoon), or even total shade.
• In regions where summer temperatures do not exceed 25°C, it is possible to expose them to full sun.

The dimensions of the daphne

• Daphne odora 'Aureomarginata' : shrub of 80 cm high;
• Daphne 'Perfume Princess' : 1,20 high ;
• Daphne 'Eternal Fragrance' and Daphne 'Pink Fragrance': dome-shaped shrubs which, at the age of 5 to 7 years, will measure 70 cm high with a 70 cm spread.

Maintenance of Daphne

Daphnes grow rather slowly. They do not require any particular maintenance. In the middle of winter, don't hesitate to make bouquets with 2 or 3 branches.

Note: Daphne wood is toxic (few pests).

Multiplication of Daphne

You can take cuttings from unprotected varieties (without patent), such as Daphne odora. Proceed in early autumn. Be careful, transplanting is delicate; do it in early spring.

Grevilleas, growing tips

Grevilleas have a strong point: they bloom almost all year round. You can have flowers from March to June/July and from September to November.

There are varieties with large red flowers but also varieties with much smaller flowers.

All Grevilleas are evergreen shrubs, very easy to grow.

The variety shown can grow to about 2 m high and 2.50 m wide, if grown in the ground. Often, Grevilleas are wider than they are tall.

Pot cultivation is possible but gives smaller subjects than in the open ground: 1.80 m high for 1.25 to 1.50 m wide.

When should I prune my Grevilleas?

The question is not insignificant, considering its long flowering period.

In fact, it is enough to intervene as soon as a flowering ends, whatever the time of the year. Take advantage of this to give it a rounded shape, always pruning after a leaf or after a young shoot.

Low maintenance for Grevilleas

Grevilleas are Australian plants that require little maintenance.

For one thing, they are very drought resistant once they are well established.

On the other hand, they do not require any fertilizer. Indeed, most plants from Australia do not like phosphorus. Since our fertilizers often include a portion of phosphorus, we do not fertilize!

For a culture in pot, the mixture to offer to its grévilléa is simple: compost, heather soil, and a little vegetable soil to give a little more body to the mixture and to avoid that it is too draining. The whole thing is placed on a bed of clay or pozzolan balls placed at the bottom of the pot, for drainage.

Grevilleas are not very hardy

The hardiness of Grevilleas is around -5 / -8°C. In the Paris region, it is therefore grown in pots rather than in the ground.

If you have a sheltered terrace, it is not necessarily necessary to bring it inside during winter, the ideal being to have an unheated veranda.

Watering for potted plants

In summer, it is necessary to water every two days and, in winter, once a week minimum. Unlike Mediterranean plants, we do not wait for the soil to dry out; the substrate must always be slightly humid.