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Using fertilizer on home-made soilless potting mix

Posted by mzmalik none (My Page) on
Thu, Sep 26, 13 at 8:50

A few quick questions:
1. How to make seed starting and potting mix at home? 1/3 sphagnum peat moss, 1/3 perlite and 1/3 vermiculite? Just to be sure, I can use this combination to germinate seeds AND grow indoor plants, as long as I add nutrients later on?
2. Regarding nutrients, I've read that one must start adding diluted liquid fertilizer to the seedlings once they develop first pair of true leaves. Any further suggestions? Any alternative to using fertilizer?
3. Lastly, if I am using seed starting mix to germinate seeds, and then using potting mix to grow the seedlings after they develop first pair of true leaves, do I need to add fertilizer to this potting mix?
Thank yoiu.


Follow-Up Postings:

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RE: Using fertilizer on home-made soilless potting mix

I would not add fertilizer to seed starting mix. Dilute by at least by 50% fertilizer in your potting mix. Too much is worse than not enough. Al


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RE: Using fertilizer on home-made soilless potting mix

What about the first question? Is that proportion of peat moss, perlite and vermiculite good for using as a seed starting mix and a potting mix?


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RE: Using fertilizer on home-made soilless potting mix

What about the first question? Is that proportion of peat moss, perlite and vermiculite good for using as a seed starting mix and a potting mix?


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RE: Using fertilizer on home-made soilless potting mix

For starting most seeds your mix sounds OK. I like to get the seedlings out of the seed starting mix as soon as possible. Mixes with that much peat and vermiculite tend to make a crust and shrink if they are not kept TOO wet, which can lead to fungus causing damping off disease. Transplanting seedlings ALWAYS leads to some check in their growth, which is less and better tolerated when the seedlings are small. Al


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RE: Using fertilizer on home-made soilless potting mix

I would use more peast moss and much less other:

50% PM ;;25% VERM;; 25% pearlite.
You can water withe diluted liquid fertilizer after germination.
Seeds dont need fertilizer to germinate and grow until yhey have a set of true leaves.


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RE: Using fertilizer on home-made soilless potting mix

Seysonn, will the soil be ok when using 50% peat moss? I'm no expert but if I use that much peat moss, will the soil retain enough air and not get water logged?


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RE: Using fertilizer on home-made soilless potting mix

Just curious. What is the purpose of using both perlite and vermiculite?


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RE: Using fertilizer on home-made soilless potting mix

since my previous post, I have learned to add something else, that is a bit coarse: PINE BARK (sifted 1/4" screen). It offers good aeration. Though perlite does that to some extent too.
This is for starter mix. For potting I will add more fine pine nuggets and bigger ones too. So here is my rough new mix:

35 % MG potting mix(Has some perlite and fert.)
35% pine fines
15% verm.
15 % Perl.

For potting I will eliminate Verm and Perl. ; Just potting mix and fine pine/fir bark nuggerts. I add some compost to it.

1/3 MG potting mix,, 1/3 pine nuggets ,, 1/3 compost.
These proportion are just approximate.


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RE: Using fertilizer on home-made soilless potting mix

Where do you buy your pine bark / nuggets from?


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RE: Using fertilizer on home-made soilless potting mix

I bought my pine nuggets from Lowes. They had two kinds : small and coarse/big. The nuggets are usually used for mulching trees and shrubs. They are usually available in most HD< Lowes and other nurseries.
Even the small ones have to be sifted for seed starting mix. Some people use orchid potting mix, the fine ones. It is also mostly pine or fir bark.


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RE: Using fertilizer on home-made soilless potting mix

Can you tell me what exactly is the use / purpose of using pine bark? I'm pretty sure that it doesnt provide the nutrients so I'm guessing either holding water or aerating the soil. So which is it?


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RE: Using fertilizer on home-made soilless potting mix

  • Posted by morz8 Z8 Wa coast (My Page) on
    Sat, Nov 2, 13 at 13:00

It's both, acts to provide some moisture and fertilizer retention, and also a bit more air space. All by itself bark does not provide enough of anything to really support plant life (except for possibly orchids), but once it is mixed with peat moss - bark fines help extend the ‘life’ of the potting mix by being relatively slow to break down.

It's helpful in container mediums for perennials, woody plants - I don't see benefit to adding it to your short use seed starting combination - I do like a container medium that is bark based for things like hydrangeas if growing those long term in pots. I have sweet box in containers at my entryway in bark based medium, it supports those well but they are supplemented with a (half strength) liquid fertilizer occasionally.


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RE: Using fertilizer on home-made soilless potting mix

None of the so-called soil less potting mixes(peat Moss, perlite, vermiculite, pine bark) has any food or nutrients. It is just a MEDIUM fir the roots to grow int it. You add nutrients to that. The only thing that might have anything for plant life could be COMPOST, if you choose to add some.

Pine/fir/cedar barks provide a better aeration and control moisture retention. So you will never have a soggy environment. The draw back is that it requires watering and fertilizing more oftern.


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