What is the clone name? It's a tight spot and you would want the slowest growth rate. P. t. 'Thunderhead' would likely get too large for this spot...and quickly.

Would you only be planting one of them on this site? It's a bit confusing because you mention having two dwarf P. t.'s. One would be pushing it; two would be asking for trouble.

Just one. One is already in the ground for 2 years(planning to transplant this one) and the other I’ll keep in the pot until I find a different suitable spot. Here’s the thing. They are both seed grown and the seed is from Japan(germinated 2019 March), they are 4 years old and neither have topped 2 ft in height yet. From my observance annual growth rate seems to be just 4-5 in for both. Grown in 5-1-1 mix so it’s not like I’m using a heavy media that obstructs root growth. The in ground one is in well drained loam next to my driveway. Both get full sun.

I had another 3 pinus thunbergii seedling(these ordered online) from 2017 and they are all in the ground at another property and over 6ft. Seedlings probably germinated in 2016. So these ones would be 3 years older than my seed grown ones but the vast difference in current height and annual growth between the 2 different clones have led me to the conclusion that mine are dwarf. I mean, it’s 4 years old and still not even 2 ft, and one has been in the ground for 2 years so it’s had plenty of time to spread roots already. Even my 3 year old chamaecyparis obtusa seedlings all exceeded the pines height already. And they‘re supposed to have a slower growth rate than the pines, and which the thunbergii species as with many other species pines usually grow 1.5-2 ft a year. Anyways that’s the background, I think I grew a seedling that ended up being a dwarf. I consider everything I just explained in this long text to be a strong backup of why I think so.

Anyway, I am also curious if planting trees near downsprouts will be an issue if it is just directed straight down in the ground and not horizontally out towards the lawn.

You should be aware that Pinus thunbergii suffers from some debilitating (and possibly fatal) afflictions on the east coast, including a high susceptibility to pinewood nematodes and an aversion to wide temperature swings and winter chill.

And that any conifer classified as a dwarf is due only to a slower rate of growth, not to any ultimate size. Thunderhead gets big!! And grows fast!

If you show us a pic we can estimate it's annual growth rate...and then estimate 10 year size....

Of course they aren't fully established so the guess would be on the low side...

There aren't many dwarf TREES ... Aka conifers that would fit in that space after a decade or so...aka tree time..ken

Mine are not thunderhead. But you are right on the size, I planted one at my father’s house and it already outgrew its space. And because I knew P. thunbergii will be shortlived with the inevitable infestation of nematodes on them, I thought I could plant one at that spot since it likely won’t live long enough to outgrow the space. But I have a very strong attachment to this species so I was planning to just keep propagating this pine and replace the dead one in that same spot over and over. I was told these pines will live in any particular spot for aproximately 20 years before the nematodes attack. So with my annual growth so far of 4-5”, in theory it will be less than 10 ft before it goes. Does this sound right?

I will make sure to take pics later when I get home

Since they are seed grown they likely will not be dwarf regardless of their parentage. At four years it is too soon to know their growth rate and I suspect in another 10 years they will be 10x10 and go on from there.

tj

Well how could you explain the rapid growth rate on my mail ordered pines that are already over 6 ft? They are the same thunbergii species as my seed grown ones(just different seed source) but one clone is growing much faster than the other. In fact those pines have already started growing a ft per year in it’s second year in the pot. But mine doesn’t grow more than 5” per year. And again, my C. Obtusa that I just planted in the ground last spring is a year younger than my seed grown pines and they are already taller. Same with my larix kaempferi seedling that I planted last Spring. A wooping 3.5 ft tall in their first season in the ground. They already grew that much even when not completely established. I understand all plants are different but there are just so many comparisons I could make with my pine from all my observations that I it’s hard to deny it’s not a dwarf.

I'd put a 'Mini' in that spot Heruga, and put the thunbergii where there's more room and sun.

These were all measured and taken today. The first pic is the mail order pine at a wooping 7.5 ft, not 6 ft as I thought. I couldn’t even take a pic with the tape measure next to it because it was so tall. This one is about 7 years old but again, started growing rapidly in its second year and in a pot.

The next 2 pics are my seed grown ones. Both of them not even 1.5 ft tall. You can see the one in the ground has longer needles though. So it definitely is growing, just not much height wise. Candles are tiny which suggests this years growth won’t be much again. Both 4 years old.

Bill, that is a full sun spot. I just took it at night time.

I saw a nice line of rugged pinus thunbergiis that I admired along a road. I was only rarely on that particular road, next year every one was totally brown.....

Heruga, they'll never grow much in a pot. Prb'ly root-bound already.

Well, I'm no expert but, comparing growth of seedlings from two different sources, is not really a good way to tell if one is a dwarf and one is not.

The ACS won't even consider registering a new cultivar until something like 5 years has passed, without the plant 'taking off' and growing at a normal rate.

ime: Many of my pines have put out one or two inches of new growth the first few years after planting, then once the roots are established, put out a yearly growth rate of one to three feet.

But whatever, if it gets too big in a few years, you can always remove it.

And from what I've read it doesn't sound like Japanese black pine have much of a life expectancy anyways.

And while we're on the subject of 'Dwarf conifers', my suspected, almost 2 year old, dwarf jack pine put out 2-1/2" of new growth this last season. That makes it 5" tall overall. Not that it couldn't go into overdrive next year. I'm still waiting to see if that's the case. ;-)

the pic with the wheelbarrow seems to be near exceeding the ACS definition of a dwarf .. once its frees from that tiny pot.. its going to double its growth rate ... imo ...

ergo.. it should be planted appropriately.. 5 to 10 feet from any structure ..

ken

https://conifersociety.org/conifers/learn/conifer-sizes-growth-rates/

Another reason why the seedlings you started from seed are smaller than the ones you purchased. Something to do with growing them in a soil-less media and not adding any fertilizer.

https://www.houzz.com/discussions/6046582/why-is-my-japanese-black-pine-still-yet-so-small

But my in ground pine that’s established is the same size as my potted one. Either ways I think I will wait another year or 2 to see whats really going on. Maybe just not happy enough, hopefully a dwarf but I’ll wait for the 5 year mark which is in 1 year.

I’ve been fertilizing for the past 2 years although I skipped it for the first 2 years. See how my potted one is green now? So it’s definitely getting more nutrients now, just not growing as much.

Yes, I can see the one in the wheelbarrow picture has put out good growth for the last two years.

I'll have to agree with beng, that's a long time to have a growing, healthy tree in a pot. Most likely root bound and will need some root surgery before planting.You'll want to do that before it comes out of dormancy.

Oh, the size of the candles tell you nothing this time of year. They will continue to lengthen once growth begins for the season and may end up being twice as long as they were last year, as alluded to by ken.

Glad to see all the progress you're having!

Keep us posted, maybe even give us a yard tour in pictures next summer/fall. :-)

I’m in Md and my Thunderhead is 10x10 feet or larger in 9 years.Planted too close to the house, beware!!

Looks nice and healthy.

But it's just getting started. Once the root system gets established, it'll really take off.

You could do some 'Candle Pruning'. That will slow it down for a few years.

Yup, I’m waiting until it gets to a decent size and then I want to start candle pruning.

This tree is an absolute monster. Looks like I’ll have to agrresively prune the candles every year from now on. Glad they are producing cones now though

Holy cow that grew a lot

That's good growth Heruga!

Good thing it's not planted under the overhang.

Where applicable, deer provide free candle pruning, at least on Jack pine they do. ;-)

Yup I planted it outside the overhang. Just didnt expect it to grow this fast.. now I’m certain this will be a full sized tree, unfortunately. Deer won’t eat this plant whatsoever and my yard’s fenced in so no deer anyway.