I've bunch of Norway spruces in pots. I planted them about two years ago. They are doing fine. Except,- growing too tall but stem looks too thin and weak.
I'd guess the growing conditions are too shady, and/or the plants are also not exposed to the wind, which stimulates stem diameter growth.
You are right. I've replanted some of them to the open space (in the ground) and since last season, they look very healthy and strong.
I have one more question. I planted small seedlings of White spruce (about 10" tall) into pots. I used 10-15-10. So far, they established well. During this season, should I use some more fertilizer or just plain water?
Depends on the weather (I'm assuming they're outdoors!). If you get a lot of heavy rain, that'll wash all the fertiliser out of the pots, and you'll need to add more.
Thanx. After they are established, should I use some fertilizer, during season or start to use it next year? I have fertilizer for evergreens 30-10-10 which I am using for older plants (4+ years)and it works very well.
