any conifer that has one growth push per season ... will not grow any further than that flush.. no matter how long the season is.. dont you think???

you must address all cultural variables in the house.. not just light ... [pot size is irrelevant ... and many would grow them in a single tray.. until large enough to pot up ... saves on media]

for me in z5 MI with my forced air furnace running full blast in winter.. HUMIDITY can not be maintained ... most of this stuff sprouts.. in nature.. in the rather damp spring ... a variable you need to address ..

then i would also have a hard time maintaining constant germinating HEAT ... again.. as the furnace kicks down to 65 at night ....

so light is not your only variables..

if you ID them all ... you might get them going indoors... sans a greenhouse ...

good luck .. sounds like fun ... do half your seed.. and save the other half for planting in mother earth ... experiment.. try both .. and then you tell me.. which .. if any ... grew more in the longer season ....

ken

ps: media is extremely important .... choose wisely .... and next time mention the netherlands.. though it doesnt matter to growing things indoors ....

It sounds like a lot of energy and resources spent for very little gain. If you're in zone 7B, your cold period should be minimal. I say they'll grow fastest if you put them in bigger pots (or the ground!), fertilize them constantly, and leave them outside under 100% sunshine.

Conifers that expect seasonal variation can have weird growth patterns in climates with no interruption in the growing season. Take a look at the "foxtails" that Pinus palustris and Pinus elliotti form when grown in Hawaii:

Here is a link that might be useful: Foxtail growth patterns of sub-tropical pines when grown in tropical areas

I've got some Picea under lights right now - More of an experiment than anything. They are in "plug" flats - 2" plugs x 3" deep. They are about 1 inch tall and growing with great vigor - I also fertilize them regularly. They seem to do fine under fluorescent tube lights - I've got them on timers for 16 hour days.

Hi joringho,

Really you are asking two questions. The answer to both is, yes.

First, can you start seeds inside over the winter, then move them outside in the spring? Sure. They're not likely to grow more in that first year. However, with the advantage of longer growing season, they'll be able to make more food and that might result in a larger plant at the end of the second growing season.

With regards to getting established seedlings growing early in the winter inside, indeed this is the basis for most conifer propagation by grafting. Understock are gradually awakened early in Dec.-Feb. so that a dormant scion can be grafted onto a growing understock. The key is that first you need to let the plant go through at least 30-45 days of temperatures at or less than ~40 F. Most temperate pines, spruce, etc. require a period of bud dormancy. Only after the buds experience an extended period of chill temperature will they start growing again. So if you bring your plants inside now, they'll likely not push at all next year. Let them experience the cold between now and, say early Jan., then bring them inside. They'll start making shoot growth in about 4 weeks time. Again though, you won't get more growth next year than you otherwise would have since most Pinacae species are determinate growers (next year's growth is predetermined), but the same considerations about longer growing season might influence the following year's growth.

Also, fluorescent lights may be okay for newly germinated seedlings, but after the first few weeks and certainly for the one year (or older) plants you'll need a more powerful light...something along the lines of HID.

Will this produce significantly larger plants? Probably not, unless a short growing season was the limiting factor in your plants' growth and that's probably not the case. But it does sound like a fun experiment.

Alex

have done this before and having had some failures I found there was some light air circulation needed to keep down the incidence of mold and to also harden the sprouts so they didn't get too long without the ability to support themselves. A small fan for part of the day did the trick

Hej..thanks for the responses so far. I did not use the best soil for many of those seedlings. I like to experiment. SO I got some loma to grow Lutz, Densata and Meyeri on. So no vermiculite, no peet or very little. In the recent past I found out that Compost, even mixed with sand and peatmoss, is certainly not a medium I want to use again.

On the rather bulky loam soil, it was so funny to see how the seedlings responded. Meyeri did not like it at all. The roots were very small, the seedlings after two growing seasons are very small. 2-5 cm.
Lutzii did reasonable well above the soil and showed the best growth. Most were 7-15 cm tall. Not good, but we have to remember this is on dense soil, outdoors and in halfshade at best (shady garden)..Densata perfomed a bit less than Lutz.

However: when I looked at the rootsystems about (10-15 seedlings per subspecies) the Meyer spruce were doing as well as the Lutz spruce (not very well). Densata seemed to like the soila whole lot underground. the rootsystem was easily 3-4 times as large with lengthy roots.

Finally: I had a whole lot of Sitka Lutz and some Brewer seedlings in the shade. I just put ém in a large terracotta pot that we no longer used. It never ever saw sunlight. I had no clue what was in the pot, I just saw it was potting soil and pH was alright. So why not. these spruce performed very well. Even Picea breweriana did much better than the Lutz spruce in the half shade! they were growing like 30 spruces on 30*30 cm. The soil was covered by moss and it resembled a small forest. My GF liked it a whole lot. But 30 spruces with a length of 30-40 cm is too much so I had to plant them elsewhere. So...was there a reason for this performance? The roots were very well developped. And it turned out at the bottom there were a lot of hydroballs (red clay). On top of it potting soil. Never gave them fertilizer AFAIK.

So I have now set up a few larger containers where I replanted the small meyer spruce in. I have used potting spil 40%/Peat moss 30% and riversand 30%. In some others, I am going to used coco peat (will rinse it very well to get rid of the salts that can be in it), mixed with either vermiculite, riversand and/or peat moss. Each container will have a different contence. We'll see what happens. Also I will put Osmocote in a few of them to see what the effect will be,

Thanks for all the comments and advice!

when i dabbled in making my own media ... i sterilized all the products first ... to avoid the bugs that can be in such ...

you only need one infestation in the house.. to drive you over the edge ...

see link ...

ken

Here is a link that might be useful: link