Soil/fertilizer for seedlings.

spartacus83April 7, 2014

Right now I have a little seedling forest growing in my window sill, I have Coast Redwood, Giant Sequoia, Douglas Fir, Engelmann Spruce and Colorado Blue Srpuce. They all sprouted in early to mid-March and all of them are in 8 oz paper cups with seedling starter soil. At what point should I fertilize them? When is a good time to transplant them into regular potting soil?


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ken_adrian Adrian MI cold Z5

not until they have been in a one gallon pot for over a year ...

they are trees.. not children.. they are genetically programmed for certain growth .. and that is what they will do .. they do not need to be 'fed'... clothed.. nor educated ...

hyperfertilizing them will not speed said process ...

i hope you have researched the first year growth of seedlings.. so you fully understand what to expect ... which is .. about 2 or 3 inches ...

they will not 'use up' the media in the cups... anytime soon ...

let me put it this way ... as a novice.. you have a greater chance of harming them by 'feeding them' ... than you do is all you provide is water .. i call it.. loving them to death ...

yes.. professional nurserymen do it differently ... and if they kill a thousand out of the million they plant.. they dont care.. but you arent them ...

they ought to be up-potted.. when you determine that an 8oz cup is impossible to keep properly watered ... in the heat of the summer ... or when the paper cup disintegrates ...


    Bookmark   April 7, 2014 at 6:33PM
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Thank you for the info, Ken. I have actually used your advice in growing seedlings with great success in the past. This is the first year I'm working with conifer seeds on my own, I'm taking notes on everything I do so hopefully I will be able to give back some advice! Btw, one thing I learn, Colorado Blue Spruce seems to have a high germination rate, about 90% of the seeds I planted sprouted and they are still alive, very unexpected!

    Bookmark   April 7, 2014 at 7:36PM
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Well first, you can't grow them inside in paper cups in your window sill very long. fill up one gallon containers with bark based container mix. slide peat media with seedling out of cup, place inside of gallon can , fill around peat with container mix, fertilizer, and water. a small amount of slow release fertilizer is appropriate. Studies have shown not only will container plants grow more than unfertilized plants but also that unfertilized plants never "catch up" in growth if they become fertilized in later years (all other factors being controlled). Finally put them outside, out of intense sun for a while. Keep watered.

    Bookmark   April 7, 2014 at 10:33PM
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fairfield8619(Zone 8 NW LA)

What winterfell said, Complete rubbish about not fertilizing in CONTAINERS, they relie on you for everything, there is no root system, so to speak to search for food. No one said anything about "hyperfertilizing".

    Bookmark   April 8, 2014 at 12:25AM
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Interesting, there seems to be a difference in opinion. I think what I'll probably do is fertilize half in separate containers and leave the other half as is and report back in autumn. I have way more healthy looking seedling than I thought I'd have so why not experiment! Any suggestion on fertilizer? Would slow release Osmocote do well? I already have some of that I use with other, older plants.

    Bookmark   April 8, 2014 at 12:37PM
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I've grown numerous plants and trees from seed and will share my fertilizing procedure/experience.
Does your "seedling starting soil" contain any fertilizer? To start seeds, I use a base mix that doesn't contain fertilizer.
Once the seeds germinate and push their first set of leaves or needles, I start fertilizing weekly during watering with a diluted liquid fertilizer. I use Foliage Pro and start out with 1/4 to 1/2 strength since the little trees have minimal and tender roots. I apply with a syringe applicator to the base of the seedling thus controlling equal amounts of fertilizer to each seedling and limiting wastage. As the root system branches and expands I use 1/2 to full strength fertilizer weekly with watering. I don't use Osmocote until the seedlings are at least 1 year old with enough roots. Hand watering/fertilizing individual seedlings weekly wouldn't work for large scale growers, but might for you. I have at least 1000 seedlings going this year and it's keeping me busy.

    Bookmark   April 8, 2014 at 1:33PM
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In addition to my other seedlings, I'm growing about 9 different Abies species from seed this year. I'm comparing the growth with three methods. I'm growing seeds outdoors with freeze/frost protection, in a hoop house with 45 degree minimum temps, and inside with 60 degree minimum temps and 6500 K T5 grow lights cycling for 18hr days. Currently a lot more of the indoor seeds have germinated and the seedlings are hands down outperforming the others. Soon I'll transplant each seedling to its own 3 inch pot and start transitioning the indoor seedlings to real sun light. I have used the same fertilizer routine on all the seedlings as I posted above.

Abies firma

Abies homolepsis

Abies pindrow

    Bookmark   April 9, 2014 at 4:51PM
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