redneck647
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Compost and seed starting?

So I've been told compost is not the best to start seeds directly in.
Usually I start seeds in potting soil and then once its thawed enough I change to soil from the one pile outside.
Since I started the compost pile last year I went out over the weekend and brought to trays of compost into the basement. Can I mix this in with the potting soil or dirt? Will it help anything or just cause problems? And if its save any idea what percentage of each I should use?

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rainbowgardener
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Re: Compost and seed starting?

I think it would just cause problems.

Soil for seed starting needs to be very light, loose, free draining. Seeds and seedlings can easily rot or "damp off" with too much moisture. Compost is the opposite of light, loose, free draining. It is good amendment for your outdoor soil, but not for seed starting. I wouldn't use any.
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ButterflyLady29
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Re: Compost and seed starting?

It can be done if the proportions are right. Seed starting mix or plain coir fiber can be mixed with compost with just enough compost added to give the seedlings some nutrients. Maybe a couple cups of compost per gallon of seed starting mix or coir fiber.

I usually use coir or bagged peat mixed half and half with fine textured potting soil and a bit of sand or vermiculite mixed in.

Now when potting up that's a different story. If you have enough light or are setting the plants outside during the day you can mix the compost with potting soil, as much as a 4 to 1 ratio, 4 parts potting soil, 1 part compost. If you have any insects or weed seeds in the compost you put your young plants at risk. I have used compost in large pots outdoors with no problems. I mix it with wood pellet bedding (which was used in litter pans in our rabbit cages) and potting soil. Usually equal parts bedding and potting soil then the 4 to 1 ratio, 4 parts mix to 1 part compost. It doesn't have to be exact portions, less compost is okay but I wouldn't do more.

I have read that watering the seedling flats with compost tea gives them nutrients and prevents damping off. Never tried it though.

Outdoor grown compost pile tomatoes always seem to grow well for nearly everyone.

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Re: Compost and seed starting?

I agree with Rainbow; start seeds with potting mix. Most recommend no nutrients until after the first transplant after true leaves appear and then only weak amounts of fertilization. I do use a potting mixture with a very small amount of time release fertilizer. After the plants are big enough for transplant to big pots or outdoors, the compost is an excellent amendment. I am not much on mixing up my own recipe for soil mixtures....too many variables. I let the pros do that and use one I have good luck with.
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redneck647
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Re: Compost and seed starting?

Thanks. And sorry for the late reply. i'll save it for when i move things to bigger pots.

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cass2828
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Re: Compost and seed starting?

I would not recommend compost for this..
Grow big or go home..

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rainbowgardener
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Re: Compost and seed starting?

Even in containers, your compost needs to be mixed (no more than half compost), with things that will keep it lighter and looser. Otherwise in a couple of months your compost will have turned into an adobe brick inside the container.
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redneck647
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Re: Compost and seed starting?

Thanks. I'll mix it in with some dirt when I move to bigger pots.

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rainbowgardener
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Re: Compost and seed starting?

Nope, not dirt. Same problem. Think light loose fluffy. Peat moss, coconut coir, leaf mould (aged, composted fall leaves or even just ground up fall leaves), perlite, vermiculite, rice hulls, store bought potting mix ....
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redneck647
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Re: Compost and seed starting?

Thanks Rainbow. I'll see what i can find then.

tomc
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Re: Compost and seed starting?

Reading on the internet will turn up some basic differences in terms between USAin and British--English. Compost in GB is like modern mixes here--a mostly peat moss soiless mix.

If you plan to grow for an extended time in pots you want very low nitrogen mixes. That have the largest particle size you can scrounge.

Short term growing in soiless mix, for annuals will work. Potting soil, or compost, not so much. Like my usual mantra about growing trees in pots, the particle size will dictate how much air the roots of your plants can get. Too fine a mix, means too little air and plants drown.
Think like a tree
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