10% perlite impact on breathability in 7 gallon grow bag

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Erratum

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I have some young plants that I just transplanted into 7 gallon grow bags when moving outside. I sit the grow bags on paver stones and put an inch of small gravel and perlite at the bottom. The remaining mix is the following blend:

10% perlite
10% worm castings
40% triple mix (humus, sphagnum peat moss, compost)
40% top soil (peat moss, compost, bark fines)

I'm having some regrets about not upping the perlite to 20%. I know this is very low on the 10% - 50% range given. I do plan to use some liquid nutes on occasion and modestly but not often enough that I was concerned about the soil holding moisture for a few days.

My main concern is oxygen. At 10% perlite and using a grow bag for breathing, do you think I will have oxygen deficiency issues in the middle of a 7 gallon bag?

Thanks!
 
Aqua Man

Aqua Man

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I have some young plants that I just transplanted into 7 gallon grow bags when moving outside. I sit the grow bags on paver stones and put an inch of small gravel and perlite at the bottom. The remaining mix is the following blend:

10% perlite
10% worm castings
40% triple mix (humus, sphagnum peat moss, compost)
40% top soil (peat moss, compost, bark fines)

I'm having some regrets about not upping the perlite to 20%. I know this is very low on the 10% - 50% range given. I do plan to use some liquid nutes on occasion and modestly but not often enough that I was concerned about the soil holding moisture for a few days.

My main concern is oxygen. At 10% perlite and using a grow bag for breathing, do you think I will have oxygen deficiency issues in the middle of a 7 gallon bag?

Thanks!
It's going to depend on your watering.

Would do ok even if none... imo the more perlite and o2 the faster the growth but that doesn't mean better product.

The key to any media is use it accordingly. I don't see anything wrong with that mix but I'm a simpleton when it comes to soil and organics. I understand the principles and watering but the nutrient values I'm lost on.

Imo uneducated organic opinion you will want to slurry test it for PH potential as you may need some lime in there looking at the makeup.

I'll link a watering thread that will kind of explain how these things affect your watering needs. This mix will have a fairly high water table so it will be important to allow the saturation zone to partially be taken up by the plants before watering again.

@GNick55 any inputs on this? As you have far more knowledge on soil and organics.

 
Erratum

Erratum

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Thanks. I'll do a slurry test in a day or two. Good point given I recall peat moss can be rather acidic.

The grow bags are black and this will probably help them dry out a little quicker in the sun. I wasn't expecting to water more than every 3 days unless the plants get thirsty when larger, so I think this is appropriate based on your points and using the soil correctly.

I'll look at the link you provided and again appreciate your time and thoughtful response.
 
GNick55

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i think you’ll be fine as there is enough wind and fresh air to dry them out.. though doesn’t look like you have any ph buffer in there? dolomite, limestone.. if it’s a recent transplant, small plant? than you could take it out carefully and re mix the soil?
don’t try to follow any schedule with watering as it may be once a week or everyday..
 
Erratum

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i think you’ll be fine as there is enough wind and fresh air to dry them out.. though doesn’t look like you have any ph buffer in there? dolomite, limestone.. if it’s a recent transplant, small plant? than you could take it out carefully and re mix the soil?
don’t try to follow any schedule with watering as it may be once a week or everyday..
Thanks. I understand not to water on a clock, I was just noting I had kept my perlite down intentionally to go further between watering.

Our local store has pelletized limestone available. I could also add a few litres of additional perlite if I'm going to mix again. The limestone is something I'm a bit leery about given it's added often based on determined pH and my slurry test may not be accurate enough. Is there a conservative ratio to add without shifting the pH too far in the opposite direction? My water here in Ontario is also rather hard and unadjusted pH is 7.5+. I was considering ceasing softened water w/ lemon juice and switching to tap water that's been out for a couple of days to eliminate volatile chlorine. Not sure how this hard water with higher pH would impact my growing medium pH if limestone is also present.

Thanks for this assistance. I do read around before asking questions, as I know people only have so much time, but precise application of the available general knowledge isn't always easy.
 
Aqua Man

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Ph is something I do know about there are different types of lime that @GNick55 could probably give you a better idea on but maybe a blend of hydrated lime (faster) as needed and dolomite lime (long term)

Lemon juice won't do anything for the ph once the water hits the soil the peat and lime will buffer it. Imo no need to ph adjust nutrients for organic soil. Concentrate on amending the soil to have the proper ph. Maybe a soil test kit could help determine how much to add

As for the ph of your water test the ppm or find a water report and look for the total alkalinity. Or take a sample to a pool or spa store and they usually test it for free. But If the soil is buffered well it should be an issue if it's drinkable and your not having to chew it... atleast for soil.
 
quirk

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I'd up it to 30% perlite to provide plenty of air pockets. The remaining 70% of your mix is heavy and will retain enough moisture to easily get you through 3 days.
Them roots gotta breathe.
 
GNick55

GNick55

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ok my advice might not be for you, as i’ve realized a very long time ago i do everything differently! haha
i’d add the lime and dolomite.
when ready put plant back in, water or not depends if it’s wet already or not.
now i’d just leave her be and watch daily.. i use a soilless hp mix.
i haven’t ph,ppm, ec, anything in years nothing, don’t even have a meter. i use tap water, have a couple 5 gallon pals sitting as i rotate using them. i feed lightly through the whole grow.
i think of the plants as children, you can do everything for them or let them figure it out on their own. it’s a fight for survival. anyhoo in no way is this advice to you..
ok so i see bark? is it so much that you can easily see it it or just a piece here and there?
also i’m in southern ontario.,
 
GNick55

GNick55

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ok my advice might not be for you, as i’ve realized a very long time ago i do everything differently! haha
i’d add the lime and dolomite.
when ready put plant back in, water or not depends if it’s wet already or not.
now i’d just leave her be and watch daily.. i use a soilless hp mix.
i haven’t ph,ppm, ec, anything in years nothing, don’t even have a meter. i use tap water, have a couple 5 gallon pals sitting as i rotate using them. i feed lightly through the whole grow.
i think of the plants as children, you can do everything for them or let them figure it out on their own. it’s a fight for survival. anyhoo in no way is this advice to you..
ok so i see bark? is it so much that you can easily see it it or just a piece here and there?
also i’m in southern ontario.,
beyond my jibberish what i’m saying bud wait to see what happens it’s either going to be 3 things
nute burn, deficiency, or fine, so why treat it, wait to see..
 
mancorn

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I know Aqua Man references the perched water table in his write up - the gravel also rises this table and water has a hard time traveling from one medium to another.

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Erratum

Erratum

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Thanks, guys. I am going to add a few more litres of perlite to the mix to bring closer to 25% and will add about 5 - 7 tablespoons of lime pellets to the upper few inches of the mix. I will also churn up the bottom gravel-perlite portion so it's blended with the bottom mix portion and remove some gravel chunks first. This should help resolve the water table issue but still let the bag breathe toward the bottom surface. The wood content is really just an occasional piece and not substantial. I know wood isn't ideal.

Is there anywhere I can donate $20 to the community? I appreciate this help and want to give back if possible.
 
Aqua Man

Aqua Man

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Thanks, guys. I am going to add a few more litres of perlite to the mix to bring closer to 25% and will add about 5 - 7 tablespoons of lime pellets to the upper few inches of the mix. I will also churn up the bottom gravel-perlite portion so it's blended with the bottom mix portion and remove some gravel chunks first. This should help resolve the water table issue but still let the bag breathe toward the bottom surface. The wood content is really just an occasional piece and not substantial. I know wood isn't ideal.

Is there anywhere I can donate $20 to the community? I appreciate this help and want to give back if possible.
You can become a supporter for $10/month which gives you some perks and a supporter badge here if you like. You could always do that for 2 months.

Here is the link.

 
Erratum

Erratum

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You can become a supporter for $10/month which gives you some perks and a supporter badge here if you like. You could always do that for 2 months.

Here is the link.

Done. Thanks again!
 
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