How to grow and care for conifers

Appearance and types of conifers

Conifers do not have true leaves as we know them. Foliage may be needle-like, as seen on the common pine tree (Pinus radiata) or blue spruce (Picea pungens), or more flattened and fan-shaped like arborvitae or thuja (Thuja spp). The variety of forms is almost endless.

Colour too is varied – from blue-grey through deep and mid-greens to gold and then there are the variegated varieties. Some plants may also have tinges of bronze over the cooler months. The deciduous conifers often colour brilliantly in autumn.

Conifers range in height, from spreading groundcovers of 30cm, through compact shrubs around a metre or so, to forest giants of 120 metres or more. Apart from the groundcovers, most form a fairly symmetrical pyramid shape. Medium height shrubs are ideal for topiary and hedging.

Many of the larger conifers like cypress and pines may make great garden plants while they are young but they should be avoided if you live in an urban area. They can reach 20 or 30m high and almost as wide and are very expensive to remove when they have outgrown their surroundings!

Columnar shaped conifers like pencil pines are a better choice but even they can become too big for the average suburban garden.

Most are evergreen but there are some that are deciduous, including larches (Larix spp) and the dawn redwood (Metasequoia glyptostroboides).

Most conifers occur naturally in the colder regions of the northern hemisphere. However, there are some notable exceptions found south of the equator, such as the Wollemi pine (Wollemi nobilis).

The name conifer has been given to these trees because they produce cones (or cone-like fruits) although there are some that break the rule and have berries. The seed-bearing (female) cones are often quite large and woody – the traditional pinecone is perhaps the best example.

Be careful where you plant larger conifers in relation to paths, driveways and underground services, as the roots can cause damage.

It's easy to get swept up in your enthusiasm for these lovely trees, but please read labels carefully and do your research before choosing conifers.

How to grow conifers

Conifers are mostly grown from cuttings. Because they are very slow growing and can take years to grow to a reasonable size, the better option is to buy young plants in 180 or 200mm pots.

Conifers do not like root disturbance. When planting out or repotting, take great care to keep the root ball intact. If a little soil falls off, don't panic but do try to retain as much soil around the roots as possible to reduce transplant shock.

Growing conifers in the garden

• Choose a sunny position without direct competition from nearby trees.
• Well-drained loam is best; poor soils can be improved with compost.
• Soil should be slightly acidic: pH 5.5–6.
• Add a six-month controlled-release fertiliser suitable for trees and shrubs to the base of the planting hole; cover lightly with soil to prevent direct contact with roots.
• Keep the planting depth the same as in the pot or slightly higher.
• Backfill around the roots; firm but don't compact the soil.
• Water in with a seaweed solution to minimise transplant trauma.
• For hedging, space plants between 60cm and 1m apart.

Conifers make excellent pot plants. Careful trimming can control height and shape so they can be kept in pots for many years, with repotting every two or three years to replenish the potting mix.

Growing conifers in pots

• Terracotta or ceramic pots are preferred – the size and shape should complement the plant.
• Choose a premium quality potting mix suitable for trees and shrub.
• Try not to break up the root ball when you take the plant out of its old pot.
• Keep the plant at the same depth as it was in its original pot.
• Position the pot in a sheltered spot for a week or so, then move into the light.

Watering and feeding conifers

Make sure your conifer is watered regularly for the first six weeks or so after planting, until it has settled into its new surroundings. When established, water only during prolonged dry periods.

Potted conifers do not like wet feet – water only when the top 5–10cm of soil is dry to the touch and make sure excess water drains away freely.

Apply a six-month controlled-release fertiliser suitable for trees and shrubs at the start of spring and autumn.

How to prune conifers

Unlike most trees and shrubs, conifers do not regrow from old wood. If you cut back hard, exposing the branches behind the foliage, you will be left with bare patches. Not a good look!

• Light trimming of the tips of shoots/branches over winter is all that is needed – cut back to a side lateral or shoot on the growing stems only.
• Completely remove dead or dying branches.
• Variegated conifers may occasionally throw shoots that have reverted back to plain green. Cut these out totally – they are often more vigorous than the variegated form and can take over.

Pests and diseases that affect conifers

There are a few nasty diseases that can devastate conifers, among them cypress canker. For most, there is no treatment. Trees will turn brown from the tips of branches and within a fairly short time entire branches will be dead. Diseased trees should be removed as quickly as possible to minimise the risk of spread.

Cinnamon fungus (Phytophthora cinnamomi) and other fungi can be troublesome in heavy soils that don't drain well.

Some conifers may be attacked by bark-boring beetles that eventually weaken trees. Look for sawdust deposits on or around trees and use a suitable insecticide if required.

If you like this, then try

Crepe myrtle: summer flowering deciduous tree with attractive bark.

Magnolia: a deciduous tall shrub flowering in spring.

Japanese maple: a deciduous small tree that colours magnificently in autumn.

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