Pinus thunbergii 'Thunderhead' / Thunderhead Japanese black pine

Pinus thunbergii 'Thunderhead' is an attractive, vigorous, broadly pyramidal selection of Japanese black pine with densely packed, long, brooding, dark-green needles and distinctive silver-white candles that are most attractive in late winter/early spring. After 10 years of growth, a mature specimen will measure 12 to 15 feet (4 - 5 m) tall and 20 feet (6 m) wide, an annual growth rate of 12 to 15 inches (30 - 37 cm). Like all cultivars in this species, specimens can be easily aesthetically pruned to control a plant's size and form.

As is true with most Pinus thunbergii, 'Thunderhead' is hardy to USDA Zone 5 although the needles could burn at temperatures of -10 to -15ºF (-23 to -26ºC). Plants are especially vulnerable during times of wide and rapid temperature fluctuation. If possible, winter protection from the effects of wind chill could greatly increase your odds of successfully maintaining this plant in your garden.

This cultivar originated as a seedling selected around 1987 by Angelica Nurseries, Massachusetts, USA. It was originally released under the provisional name, [Angelica's Thunderhead] and at some point the cultivar name became shortened into its present form.

One must note that in 1981, Dr. Sidney Waxman of University of Connecticut selected and named a Pinus resinosa under the name 'Thunderhead.' Under the rules of botanical nomenclature, a cultivar name can only be used once within a genus, leaving P. thunbergii 'Thunderhead' as an illegitimate cultivar name because P. resinosa 'Thunderhead' was named first. I would be most appropriate if 'Angelica's Thunderhead' was re-adopted as a cultivar name for this conifer.

Pinus thunbergii 'Thunderhead' A larger specimen for reference purposes. Photo taken at The Gotelli Collection in the U.S. National Arboretum, Washington, D.C. in May 2006.
Photo by Dax Herbst
Pinus thunbergii 'Thunderhead' This specimen grows in the Oregon Garden in Silverton, OR and is part of the Conifer Garden display; photo from October 2002.
Photo by Charlene Harris
Pinus thunbergii 'Thunderhead' in a private garden in Illinois, USA. (Photo from 2006).
Photo by Daniel Wols

Comments

Eric Smith

In only it's 2nd year in the ground mine pushed out a 15" leading candle! We may need to revise it's dwarf status.

David Olszyk

Hey Eric . . .
indeed 'Thunderhead' can be a beast, albeit a beast that is easily controlled through aesthetic pruning. I've revised the macro-record to correct its fictitious dwarf status. I'll tighten up the rest of the record tomorrow.

Eric Smith

I probably should have prefaced my earlier statement by mentioning that my 'Thunderhead' gets full south-facing sun, and plenty of supplemental water. I would bet that contributed quite a bit to it's significant 2nd year growth spurt. What will year three have in store for me I wonder? I imagine I will take your advice and start my aesthetic pruning early. Thanks CE!

David Olszyk

Growing conditions aside, 'Thunderhead' over time, becomes one big bad pine. I debulk mine by about 2-thirds every year to keep it in line.

Website Editor

A thug. Everyone gets seduced by those incredible white candles in the dark foliage and then it gets in the ground, gets happy, and becomes a huge wooly bear. I have aesthetic pruners work on mine twice a year and they've taken off about 50 x more than is still on the two plants. You'd better have a lot of room...

Lisa Kessler

I didn't leave enough room when I planted mine three years ago. Can I dig it out and move it this spring? I'm in Boston.

David Olszyk

Hi Lisa. If you're interested in the plant's survival, it might be best to wait until September or October. That way it can grow roots before the stress of summer.

Cynthia Kling

Can I keep mine small by pruning?
When do I prune it?
Thanks!

David Olszyk

Hi Cynthia ... If you're goal is to "keep it small," you'll need to cut on it at least 3 times a year.

First round is in spring as candles are extending. Get rid of all of the strong candles and leave only a few of the tiniest buds at the ends of the shoots. Then when the needles have extended 3/16th of an inch from the fascicle, reduce the candle size to 2-3 whorls of needles.

Second round is in early summer. Hunt for back buds and shorten shoots to just above them. Also prune the whole plant for shape.

Third round is in fall, once everything is done growing for the year. Prune off everything you missed in rounds 1 and 2.

Keep in mind that this cultivar is an absolute beast and if you neglect it, it will explode with growth in a single season.

Inga

I'm debating where to put Thunderhead in our garden - a container or in the ground. In 8b Tacoma, WA. We have a bit sandy, rocky, well drained soil...it would probably be happy in the ground here. What size will it live with comfortably at maturity? I don't mind pruning it and thinking I'd like to style it a little. Guess I'm kind of nervous since reports vary so widely about it's eventual size. I don't want to be constantly fighting off something that wants to be 20' monster in the front yard.

David Olszyk

Inga, I can offer this first-hand report based on observations and my own plant in USDA zone 8a, Olympia, WA ... 'Thunderhead' is a beast that will grow 2 feet or more per year if left to grow free range. Give it room, or be prepared to prune it heavily at least twice a year.

It definitely wants to be a 20-foot monster and it wants to get there fast.

Inga

Thanks for the reply, David. Container and lot of pruning it is, haha. :)