Garlic & Onion Husks As Mulch: Good Or Bad?

[DexterC]

Hey guys!

Recently I've been struggling with a small thing. Since I am growing in completely organic medium, I need to keep my soil moisture in check. As my little seedlings are going through a "hardening process" and they get plenty of "wind" from my fans, the top part of the soil (about 2.5cm or 1 inch deep) keeps drying out. My tiny ecosystem, of course, is suffering because of this, and since the pots are small and I had these laying around made me wonder... could onion and garlic husks make a good mulch?
Some of you, and many internet guides would say that at this point you should give them more water, and that is a bad idea. At least in my environment. Those pots are wide and my soil holds water well. Watering at this point would cause over-watering. Not bad, but enough to get their leaves droopy and make them sad for a while. Happened already yesterday and thought I f***ed up. Fortunately, today they were happy, but I knew I had to deal with this.

So... I had some onions laying around, as well as some garlic bought from the local grocery store. Interestingly, the onions had dark patches of what looks to be some pretty healthy soil which leads me to believe these were grown in organic medium too. It is only an assumption though. No complaints there if that's truly the case. Anyway... I've torn apart the top layers of the onion and garlic husks and broke them down into smaller pieces.

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After that, of course I mixed them together.

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Then I sprayed a small amount of water on top of the soil.

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After that, I covered it with the onion and garlic husks mix and sprayed a bit more water on top.

The colors look really neat and all, but that makes me wonder... since onion and (maybe) garlic got anti-bacterial properties, could they be harmful to the good bacteria too? Or could this be just a good, beneficial and totally free mulch to keep the soil moisture in check, at least in the early stages until they get moved to larger fabric pots and White Clover, for example can be used?
What do you guys think? Does it even work?


In case you're wondering...

Soil: 60% Peat Moss Base pre-mixed with Perlite, 20% compost, 10% worm castings, 10% bone meal. Soil was "activated" several days before planting the germinated seeds.
Water: Purified water, pH 6.8 - 7.1, 54 PPM which is mostly Calcium and Magnesium and trace amounts of Sodium, Nitrates and other minerals. The same water I drink
Relative Humidity: 62 - 68%
Temperature: 23-26 Celsius or 73-76 Fahrenheit
Lights: Viparspecta P2000, dimmed to about 60% and at a 1.1m (3.6 ft) distance from the seedlings.
Seeds: 1x White Widow & 1x Dark Phoenix by Green House Seed Company
Age: 13 days.

 

[013]

Hey Dexter,

the outer most dried up layers of skin should be ok…. it will however add a “potential” flavor component and may help with pest deterrence…. but as far as mulch goes the skins are paper thin so prolly not very effective as mulch

as far as flavor goes…. most likely it’s too slight for humans to notice however I’m a firm believer that the flavor of a weed plant can be manipulated while the plant is growing…. if you continue adding onion & garlic skins as mulch over duration of this grow then dont be surprised if you detect slight garlic or onion scent notes in your bud.

I was crop dusting on fungus gnats with cinnamon powder and as a result there’s a flavored cannabis thread in my signature line below if you are interested, I’m just getting my garden back on its feet after the mother of all pests invasions but hopefully the flavored cannabis thread will move forward soon

 

[bluter]

i woulda gone in to a much much bigger pot. bigger pot will regulate the water table better and provide a better base of nutes for the plant to develop.

it won't take long for those plants to deplete the available space and nutrients in those pots. maybe a wk or two at most before you need to up pot again.


straw is often used to help with retention. go have a look at what @Nunyabiz is doing with his organic grows. most organic mixes need to be mixed and 'cooked' for a number of weeks before they are ready.

 

[SmokingWings]

The colors look really neat and all, ...

The color combination does look neat, especially since it matches the flower pots and contrasts nicely with the green of the plants.

Good thing is that onions have a decent amount of sulphur in them. Marijuana plants need sulphur. How much sulphur is in the skins as compared to the moist layers? Using the dry skins might not make any difference as far as sulphur is concerned.

Your questioning if the onion anti-bacterial aspects would affect the soil bacteria and micro-organisms sounded interesting. A quick search of the internet indicates it is not a problem but that was just quick.

Regarding the surface drying out, I don't see is as being that much of a problem. Two things are happening when the surface dries. There is a degree of capillary action going on and as the top layer of soil dries it pulls a small amount of water up which among other things will help keep the water lower down from being stagnant. At the same time, as the water leaves the soil it allows air, especially oxygen, to flow into the spaces between particles of soil and organic material.

I mulch like crazy in the outdoor garden bed areas. Indoor pots, nope, except for the occasional times when I might want a decorative effect and decide to do something about it.

It is all a balancing act.

 

[Sueet]

I sometimes toss a few river stones on top of my pots if I feel like they are drying 'too' fast. I don't cover the soil completely, literally just a few spread out (closer towards the edges usually)

 

[Nunyabiz]

I agree with Bluter
Those pots are good for maybe 10 days just to get a seedling started.
Your soil is going to give you a problem as there is no where close to enough aeration in it.
The peat mix probably had maybe 15-20% perlite if you're lucky but by adding the worm castings and compost both of which are very heavy with no aeration then your final mix is probably at best 10% aeration.

You need a good 30% of the soil as aeration, like pumice, rice hulls, a little biochar.
You don't really want soil that "holds water" that usually means that it doesn't hold oxygen.
Without oxygen it all dies and becomes anaerobic.

I would advise using a Clackamas Coots soil recipe and putting it in MUCH larger fabric pots.
The bigger the pot the more available nutrients and the larger the buffer to prevent shyt going south, it gives you room to make mistakes and the time to recover.
As far as mulch personally if you want to do an actual organic grow then I would do a combo of green and brown mulch, use a sparse cover crop that you plant before you ever plant the cannabis to get some roots in the pot to get the microbes going and some exudates so the soil starts to come alive prior to planting the cannabis.
Then some organic barley straw, if its not organic it could have been sprayed with Darwin knows what , pesticides, fungicides etc.
You want a thick mulch layer.
Put in a handful of worms to help break down amendments and aerate the top 4 to 5 inches of soil.
The roots from the cover crop also help aerate.

 

[DexterC]

@013 The mulch is only temporary, so I am not worried about this messing the taste, especially because I don't really water a lot, just a bit of spraying every few days. I don't think it will have enough time to make any impact on the soil composition.

@Butler & @Nunyabiz these girls were never meant to stay in these pots. And thankfully no others will ever have to do. I was just in a hurry to start them and had nothing better on hand so I used these and drilled bigger drainage holes. They will stay here another week and a half or so until they get transplanted in lager fabric pots for the vegetative phase. The soil composition will include more Perlite as well as Mycorrhiza and all other goodies. The reason I did not add extra Perlite is because I did not have any as not all orders arrived on time and the soil is airy enough not to cause major problems. Despite appearances the mixture has a spongy texture. I agree that watering until completely saturated will cause over-watering problems in this soil, which is why I don't actually water, I just use a spray bottle to spray some water regularly. That is what I've done for the past 2 weeks from sprout and they seem to be loving it.
Until I added too much...

@Sueet never crossed my mind to use stones. Ironically, I live on an island in the middle of the Mediterranean Sea (Malta), which pretty much rock. Pebbles are everywhere here. I guess sometimes it's exactly what's under your nose that you can't see

@SmokingWings thanks for telling me about capillary action, I did not know about it, researched a bit, that makes sense. I also did a bit more research regarding the anti-bacterial issue and I agree, there shouldn't be a problem in the short amount of time I plan to keep these here.

So... as an update, after a day of keeping these on top of the soil, a bit of research and the information from you guys, here my thought so far. Although you will have to take my word for it, it did seem to work to some extent. It did not stay as moist as it was, of course and a better mulch in a bigger pot would have done a much better job as you guys pointed out, but about a day later the top layer still has a reasonable amount of moisture and surely it did protect the top layer from the fans which to me is... well... better than nothing considering it's a temporary solution. In conclusion, the girls seem to be extremely happy at this point. No sign of over-watering or issues with aeration or anything. So... I don't think that I have to do anything except maybe spray a bit of water some time early this week. Regarding the biology in the soil, I guess the little ones should be good, now that I managed to put some balance in moisture, that should only benefit them.

Anyways, thank you guys for your opinions, like always, really comprehensive information and definitely worth it. All in all, this was rather a test as much as a temporary, mediocre solution. Would I do this again in the future? Certainly not. Not the pots, not the mix, not the rather fancy-looking mulch, but on the principle "something is better than nothing", I find it helpful to some extent when no better options are available. But so long the little ones are happy and they stay happy, I guess nothing else matters.