The blue spruce

Conifers · tree portrait

The blue spruce

From the Rocky Mountains, and in Europe the best-known blue conifer of front and back gardens. Lovely to look at, painful to touch.

Picea pungens
Blue, prickly needles
State tree of Colorado

Picea pungens

Summary

The blue spruce in brief

A stiff, conical spruce from the Rocky Mountains with needles that a waxy coating turns blue to silver-grey.

In the mountains of Colorado, Utah and the surrounding area it grows along streams and on cool slopes. It is the state tree of Colorado. Its scientific name pungens means 'prickly', and you can feel it: the needles are stiff and razor-sharp.

The blue colour comes from a waxy coating on the needles. In the wild it ranges from green to steel blue; nurseries have selected the bluest forms, such as the well-known 'Glauca' and 'Hoopsii' cultivars.

Why it is blue

A waxy layer on the needles reflects light and protects against drying out and strong sun. It wears off over the years, so older needles often turn greener.

Botanical: Picea pungens
Origin: Rocky Mountains, North America
Height: 25–30 m in the wild, usually smaller in European gardens
Needles: four-sided, stiff, very prickly, blue to green
Bark: grey, scaly
Wood: no commercial timber of note

To be fair: blue spruce wood is knotty and of little value. The tree is planted for its colour, not its wood — and in a small front garden it often outgrows its space in time.

Recognising

How to recognise a blue spruce

Blue sprucePicea pungens

Blue colour

Blue to silver-grey from a waxy coating, especially in the cultivated forms.

Razor-sharp needles

Stiff, four-sided and so sharp that you would rather not grab hold of it.

Stiff, regular shape

A broad, regular cone with horizontal branches in distinct whorls.

Grey bark

Grey and scaly, without the reddish-brown of the Norway spruce.

From tree to plank

The wood of the blue spruce

Knotty

Because of the dense whorls of branches, the wood is full of knots.

Light and brittle

Light in colour and weight, and more brittle than spruce timber.

Not a commercial timber

It is hardly ever sawn; the tree is planted as an ornamental and a Christmas tree.

Christmas tree

Thanks to its sturdy branches and colour, it is also sold as a Christmas tree — decorate it wearing gloves.

A tree that needs space

In the wild the blue spruce becomes a sizeable tree. If you are planting one in a small garden, a slow-growing dwarf form is the better choice.

Quick answer

Frequently asked questions about the blue spruce

Why is the blue spruce blue?

Because of a waxy coating on the needles that reflects light. Cultivated forms have been selected to be extra blue.

Is a blue spruce prickly?

Yes, very. The needles are stiff and very sharp; the name pungens means 'prickly'.

How big does a blue spruce grow?

25 to 30 metres in the wild; in gardens, the cultivated forms in particular usually stay smaller.

Is blue spruce wood used?

Hardly at all. It is knotty and of little value; the tree is there for its colour.

The blue spruce in perspective

An ornamental tree best admired with your eyes — and preferably not with your hands.

The spruce tree Conifers To The Wood Guide

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Photo via Wikimedia Commons: Picea pungens — James St. John, CC BY 2.0

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The blue spruce

The blue spruce

The blue spruce in brief