Temperatures for growing black pine seeds

[syon_r]

I want to try the Japanese black pine from seed contest. I am going to stratify them in February or March, and plant in April. In Denver in April average low temperatures are around 35 degrees. Should I grow them indoors until May or June when temperature lows are in the 50s and then move outside? Also, how long after planting are seedling cuttings usually made?

 

[MichaelS]

Black pine does not need stratifying. Store dry in a jar in the fridge during the winter then in spring soak in warm water overnight and sow. Do not sow indoors or in low light. Rub some nice white mycorrhiza into the sowing mix which should be reasonably coarse. If you have old seed it won't hurt to stratify first but if it stored correctly it should be fine. This spring I put down some Pinus sylvestris var mongolica seed which I had in an unopened glass jar for 20 years at the back of the fridge. 100% germinated.
A good temp for sowing pines is about 7C to 17C . Not too warm and plenty of sun. 50F is about 10C You make cuttings when the stems go purple. The best medium by far for pine cuttings is fine vermiculite over sand. I don't bother with cuttings anymore.

 

[syon_r]

Black pine does not need stratifying. Store dry in a jar in the fridge during the winter then in spring soak in warm water overnight and sow. Do not sow indoors or in low light. Rub some nice white mycorrhiza into the sowing mix which should be reasonably coarse. If you have old seed it won't hurt to stratify first but if it stored correctly it should be fine. This spring I put down some Pinus sylvestris var mongolica seed which I had in an unopened glass jar for 20 years at the back of the fridge. 100% germinated.
A good temp for sowing pines is about 7C to 17C . Not too warm and plenty of sun. 50F is about 10C You make cuttings when the stems go purple. The best medium by far for pine cuttings is fine vermiculite over sand. I don't bother with cuttings anymore.

But most websites and people recommend cold stratifying. Apparently according to Jonas Dupuich, it increases the germination rate. He wrote it here: https://bonsaitonight.com/2012/05/11/pine-seedlings/

 

[MichaelS]

But most websites and people recommend cold stratifying. Apparently according to Jonas Dupuich, it increases the germination rate. He wrote it here: https://bonsaitonight.com/2012/05/11/pine-seedlings/

I won't hurt but like I said they do not require it. Some species do some don't. Black doesn't

 

[Anthony]

Syon_r,

Tropics here. We just soak overnight and plant. Since late 1980's.
I do suspect the seeds we get have been in cold storage for a while.
Black pines out of Japan, grow all the way down to the seashore.
That is zone 10.

What was reported was that around New York [ zone 7 ? ] it is
better to shift to Scots pine.

Unlike Michael, we no longer use seeds, just hardwood cuttings.
Often off of the more vigorous plants.
Good Day
Anthony

 

[dirk hoorelbeke]

https://www.bonsainut.com/threads/experiment-with-stratification-jbp.18561/

Most of the time what you reed is correct. But i don't believe it all the time. My conclusion of the experiment was that stratifying produces faster and more uniform and more efficient germination. I did it 3 months. I think this is way to much. This year i'll do 2 months. As stated before success will depend on the freshness of the seeds and the storage before you start stratifying.

 

[Potawatomi13]

Kept indoors under light would suspect more likely damp off/weaker plants. If planted outside about time temps warm will get stronger seedlings starting in genuine "hard" sunlight and will emerge at own optimum time to survive.

 

[Anthony]

You might have to match the sun's intensity to grow indoors -
say 2000 lux [ is it a lux = 10 footcandles ?]
Or more ?

 

[jeanluc83]

IMO pines are actually the strongest and most resilient when they are seedlings. After all they can have all their roots cut off and then regrow them as if nothing happened.

I would start them outside in full sun but protect from late frost. I think starting them inside would just cause more problems.

Remember that the first thing you learn about bonsai is that all trees are outside plants. This applies to seedlings too.

 

[Nybonsai12]

If you decide to start indoors I’d recommend a good lighting system, a heat mat and to protectively spray for fungal concerns.

 

[syon_r]

Syon_r,

Tropics here. We just soak overnight and plant. Since late 1980's.
I do suspect the seeds we get have been in cold storage for a while.
Black pines out of Japan, grow all the way down to the seashore.
That is zone 10.

What was reported was that around New York [ zone 7 ? ] it is
better to shift to Scots pine.

Unlike Michael, we no longer use seeds, just hardwood cuttings.
Often off of the more vigorous plants.
Good Day
Anthony

Since Denver may be a bit to cold for Japanese Black Pines, I am wondering if grafting them to scots pine roots would help cold tolerance. Denver is on the edge of the climate zones for Japanese black pines, so would grafting this onto scots pine increase their cold tolerance so I can grow them?

 

[dirk hoorelbeke]

How cold is cold?

 

[syon_r]

How cold is cold?

Denver is 5b so I guess -15 is the lowest it could go.

 

[dirk hoorelbeke]

Sounds like Belgium once in a while. Most of the time it is -5 to -10 tops. I wouldn't bother grafting. They tolerate the temp's here. I do shelter them for wind in a poly tunnel but minima stay the same.

 

[syon_r]

Sounds like Belgium once in a while. Most of the time it is -5 to -10 tops. I wouldn't bother grafting. They tolerate the temp's here. I do shelter them for wind in a poly tunnel but minima stay the same.

I meant -15 degrees Fahrenheit. Belgium is much warmer than Denver. But -15 is the absolute lowest Denver could be so it isn’t like it would be this temperature for prolonged periods.

 

[Anthony]

@syon_r ,

look up the qualities of the Scots pine, see if you like the tree for what it is.
Example - needle length, bark, etc.
Good Day
Anthony

 

[dirk hoorelbeke]

-15 Fahrenheit is cold. I love Scots pines. Smaller needles and more delicate. Cold resistant.

 

[River's Edge]

I have had great success with the following routine. Plant only the seeds that sink when soaked overnight, discard the floaters. Cold stratify for 30 days. I use fine pumice in the seed tray, sow 1/4 inch deep. Cover with finely screened sphagnum moss. I use a small computer fan to keep air movement over the seed tray. I have found the color change in the stem to be unreliable and have had better success waiting for the second set of needles to form before cutting. This usually occurs approx 60 days after germination. I start indoors and move out when temperatures are warmer and any risk of frost is over. I allow the seed tray to dry slightly between watering. The pumice is a great aid in that regard as it turns white as it drys out. So when the surface is turning white i water using my fine mist spray bottle. I have not found it necessary to use any chemicals.

 

[jeanluc83]

I start indoors and move out when temperatures are warmer and any risk of frost is over.

I'm a fan of putting them right out into full sun after the seeds have been planted. You have to be sure not to let them dry out. It is also advisable to cover them with something to keep the bird away.

With them starting out in full sun you don't have to work them into full sun later on.

 

[syon_r]

I'm a fan of putting them right out into full sun after the seeds have been planted. You have to be sure not to let them dry out. It is also advisable to cover them with something to keep the bird away.

With them starting out in full sun you don't have to work them into full sun later on.

How often do you need to water? A few times a day? Also do you put sand on the top of the soil or use a special seedling soil mix to retain moisture in full sun?