Monterey pine

How to recognise it

Habit

Large tree of 20–30 m, conical at first, later with a broad, rounded or flattened crown. The trunk is thick and sometimes forked on old trees.

Needles

Usually in threes in a sheath, 8–15 cm, soft, thin and bright green to grass green; they are densely crowded around the shoot.

Cones

7–15 cm, egg-shaped and clearly lopsided: the scales on the outer side are much thicker and more swollen. They sit in whorls close against the branch and often stay closed on the tree for years.

Bark

Dark grey to blackish brown, thick and deeply furrowed.

Roots

A strong root system, but on wet or shallow soil it stays near the surface and the tree can blow over in a storm.

Confusion with

Maritime pine: needles in pairs, stiffer and longer (15–25 cm), and long, symmetrical cones. Bishop pine: needles in pairs and cones with sharp prickles on the scales. Canary Island pine: needles also in threes, but much longer and drooping.

Flowering: March–April · Pruning: February–March and June

Why grow it?

• Grows exceptionally fast: in good conditions young trees can put on more than a metre a year.
• One of the best pines for a coastal windbreak: it tolerates salt and strong sea winds.
• A dense, bright green coat of needles that looks fresh all year round.
• The dense crown gives birds cover and nest sites; seed-eaters such as siskins and crossbills take seed from open cones.
• A tree with a story: from a few coastal forests in California to plantations all over the world.

Monterey pine: where does it grow best?

• In the wild: cool, misty coastal slopes with mild winters and dry summers, on sandy and loamy soil.
• Full sun; it tolerates sea wind and salt spray better than most pines.
• Deep, free-draining, preferably slightly acid to neutral soil; it grows less well on very chalky or wet ground.
• In Belgium: only for a large garden or park in a sheltered spot, preferably in a mild coastal or urban climate.

Goes well with

• Monterey cypress: Grows with Monterey pine in the wild and copes just as well with sea wind.
• Sea buckthorn: A native, salt-tolerant shrub with orange berries for birds, ideal in a coastal windbreak.
• Gorse: Yellow flowers in spring on the same acid, sandy soil.
• Heather: Low, flowering ground cover on poor, acid soil, full of bees in August.

Monterey pine: when and how to plant it?

1. Buy a small, pot-grown tree from a tree nursery. Never take seedlings or young trees from the wild.
2. Plant in April–May so the tree is well rooted before winter.
3. Choose a young tree of 40–80 cm: larger pines establish less well and blow over more easily.
4. Dig a wide planting hole, loosen the bottom and set the root ball at the same depth as in the pot. No fertiliser in the hole.
5. Drive a short stake in at an angle on the windward side and water in thoroughly straight away.
6. Keep at least 10 m from houses: it soon grows tall and wide.

Care

Water

Regularly during dry spells in the first year; after that only in long heatwaves.

Feeding

Not needed. Leave the needle litter in place.

Windbreak

For a windbreak, plant a loose row with trees 3–4 m apart; they soon close up.

Winter protection

For the first few winters, protect young trees in severe frost with fleece over the crown.

Storm damage

Have large, older trees checked now and then: they are prone to branch breakage and blowing over in storms.

Tip: For a quick windbreak by the coast or in an open, windy spot, plant small, young Monterey pines in spring: they root better than large trees and soon overtake them.

Pruning and mowing

Pruning months: February–March and June.

When: Little needed. Raise the crown and remove dead branches in February–March in dry weather; cut out frost damage in June.

How:

• Saw off dead, broken or diseased branches close to the trunk, just outside the branch collar.
• If you want to walk under the tree, remove the lowest branches gradually over a few years.
• On a young tree, keep a single leader and cut out any competing leader.
• Prune in dry weather: wounds made in wet spells are an entry point for fungi.

Caution: Never cut into bare wood without needles and do not top the tree: a pine will not regrow from there and loses its shape.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

The cones often stay closed; put them in a warm place until they open. Sow in March–April in a seed tray with light compost; the seeds usually germinate without pre-treatment. Pot the seedlings up quickly.

Cuttings

Nurseries root cuttings from very young plants, but for the amateur sowing is the usual method.

Monterey pine: how does it get through the winter?

Hardy to −12 °C: protect in harsh winters.

• Evergreen, with a fresh green crown in winter.
• Moderately hardy: down to about −12 °C without much damage. In harder frost the needles turn brown and branches may die.
• Wet snow can break branches; gently shake the snow off young trees.
• The closed cones stay on the tree; sometimes they only open in great heat.

Diseases and pests

• Red band needle blight: A fungus that causes red bands on the needles, which then turn brown and drop, especially in wet years. Choose an airy spot and clear up fallen needles under young trees.
• Shoot dieback: Young shoots die and hang on with brown needles, often after hail or drought. Cut them out in dry weather back to a healthy side branch with needles.
• Frost damage: Brown needles and dead shoots after a severe winter. Wait until June to cut them out; it often regrows.
• Windthrow: On wet or shallow soil it roots near the surface and can fall in a storm. Plant on deep, free-draining soil.

Through the year

• January: Dormant. Check for broken branches after heavy snow.
• February: Raise the crown and saw off dead branches in dry weather.
• March: Flowering begins: male cones release lots of yellow pollen. Pruning still possible.
• April: Flowering. Plant young trees.
• May: Planting. New shoots grow fast.
• June: Cut out frost damage and dead shoots. Water young trees in dry weather.
• July: Water young trees in hot weather.
• September: Watch for reddish-brown bands on the needles.
• October: Collect closed cones for seed.
• December: Evergreen. Protect young trees in severe frost.

Did you know?

• It grows naturally in only a handful of places, yet as a plantation tree it covers millions of hectares, especially in New Zealand and Chile.
• Its cones can stay closed on the tree for years; after a forest fire they open and reseed the burnt forest.
• In parts of the southern hemisphere, such as South Africa, it escapes from plantations and is controlled as an invasive species.