Warning: Miracle Gro Moisture Control

Crofter55June 10, 2012

I have 4 enormous ornamental planters in my gardens, which I have planted with purchased annuals for over 20 years. I am very experienced, and these planters have excellent drainage. This year, I switched the potting soil out for Miracle Gro Moisture Control. I flooded the planters before putting the plants in - several times. I planted them, and watered every single day from necessity. This soil product felt moist, but none was shared with the plants - their soil root balls stayed bone dry. The 2 planters in full sun had dying plants. I plunged my arm at least 25 inches down into the planters and the soil was hotter than beach sand, all the way down. This product somehow retains heat and was cooking my plants. When I removed this soil, I was surprised to find big pockets of it that were dust dry. The 2 planters in shade did a little better, but no plant growth whatsoever. Maybe if the plants grew in this from seed, they would do better, but you can't put plants in root balls into it - this soil just won't let the moisture leach into adjacent soils. And it cooks them. If your plants are still alive, rescue them and replace the soil. I don't know what this stuff is, but I would definitely not eat anything grown in it.

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What ever your problem it has nothing to do with the MGMC.

I have been using it for years with excellent results.
Have it in 6, 15 gallon pots with Tomatoes and one Bell Pepper and also in a large Vegtrug with 380 quarts of straight MGMC and nothing else.
In the tomato pots I have it mixed with a bit of Moo-Nure cow manure and compost mix.
You have to really soak the mix very well initially and have very good drainage.
All my tomatoes were transplanted into it.
Other than that there is no "Warning" to be had.

Works excellent.

    Bookmark   June 11, 2012 at 7:40AM
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greenman28 NorCal 7b/8a

Terrible stuff.
If you value your plants, seek something else.


    Bookmark   June 11, 2012 at 11:32AM
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LOL, yet magically everything I have planted in it for many years grows like mad with never a problem of any kind.

So obviously cant be all that bad.

Here is my Tomatoes growing in this terrible stuff.

This Bush Tomato was 3" tall on April 28th, its over 4 feet tall now and its not even supposed to be 4' tall max height.

Green as can be, healthy as an Ox, loaded with tomatoes.

Bell Pepper growing is MGMC, over 4 feel tall, have already harvested 8 nice pepper from it in the past 2 weeks, there are 6 I am going to harvest today for dinner and there are at least 25-30 more on it.

Here is my Vegtrug filled with 380 Quarts of MGMC not mixed with anything else.
Its like a freaking jungle, the Bok Choy and Basil and Rosemary, Lemon Thyme, Cilantro, Lettuce growing so fast I cant even eat it fast enough, I had to prune the Basil just this morning and put 2 large branches in a jar with water in the kitchen. Will be pulling 2 Bok Choy for dinner also.
Have already pulled 7 Bok Choy and 3 Lettuce in the past 2-3 weeks and pruning the Rosemary wildly, I used several large branches last weekend just to throw on the smoker for smoke flavor.

So clearly what ever problems you may have has zero to do with the potting mix itself.
. .

    Bookmark   June 11, 2012 at 12:56PM
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Ohiofem(6a Ohio)

Where are you growing Nunyabiz1? Your experience is different from most on this forum. Your containers are also larger than most container growers use. Your garden is impressive. My experience with peat based mix has been very different in the Ohio River valley.

    Bookmark   June 11, 2012 at 10:46PM
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I am in Raleigh North Carolina which is notoriously BAD for growing anything.
That is why I am growing in large pots on my back deck.

Everything we have is growing in MGMC, every flower, every vegetable, a small sweet bay tree, and all doing very well.

I always use large containers minimum of 10 gallons, though usually 15+ gallons which I think is key for tomatoes and peppers.

The Vegtrug was an experiment this year, 1st year.
Next year I am going to stagger planting.
Plant a row of Lettuce then a row of Bok Choy wait 2+ weeks then plant another row of each and so on.
The herbs should still be there except for the Cilantro I will leave a little corner for that.
Everything is growing so fast that I cant eat it quick enough.

One nice thing about the Vegtrug though is the bug net, all my Lettuce etc is all bug free without any need for pesticides of any kind.
Also has a green house cover for winter so I grow Lettuce probably all year long.

    Bookmark   June 12, 2012 at 7:46AM
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susan2010(6 Massachusetts)

I'd be interested to learn if the MGMC is the same. I noticed on a bag of Schultz potting mix, for instance, a note indicating that depending on where the product is purchased, pine bark fines replace some/all of the peat. So I'm not sure that these mixes are uniform ... I think at least some of them differ regionally. That might account for the varying experiences of some with these products.

    Bookmark   June 12, 2012 at 9:45AM
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I looked on the bag and it does say that it is "regional" but they only listed one place as having anything different as far as percentages and that was Georgia which contains 50-60% peat. I would think that no matter what brand or type of potting mix that they are all a bit different from batch to batch though.

But this is what the company says it contains.

"Our potting soils generally contain peat moss (the major component that is harvested from natural peat bogs), compost (the compost may contain animal manures, composted leaves, grass clippings, and/or composted bark), and perlite (white volcanic rocks used for drainage and soil texture). Osmocote fertilizer that look like small clear fluid-filled balls.

The Miracle-Gro Moisture Control Potting Mix also contains composted hulls of coconuts to help absorb more water than regular potting soil. This is the Aqua Coir (pronounced "core") component of the soil.""

It always looks good and looks the same to me and I bought 15, 55 Quart bags and 1, 64 Quart bag of it this year.

Much more than I have ever bought in the past because of the Vegtrug which took 7 full bags of it.

I also bought 2 bags of Moo-Nure to mix in the MGMC in the pots for the Dwarf tomatoes.
Everything else is straight MGMC.
Although I think in the future I am going to amend it with the Moo-Nure a bit for everything just to give it that extra nutrient content.

    Bookmark   June 12, 2012 at 10:54AM
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I've always found this stuff or any other peat dominant soil less mix a pain to use. Yes, you can get stuff to grow in it if you are experienced and very careful with it, as it goes from saturated to hydrophobic at the blink of an eye, and roots are thin and brown in it. I prefer a much more aerated mix that is much more forgiving, where you can leave it out in the rain without worrying about saturation. And yes, larger pots act as a larger buffer, but who wants to use a much larger pot then is needed with a better soilless mix?

    Bookmark   June 12, 2012 at 4:03PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

Magic moisture crystals are good for growing magic beanstalks. It's a real chore to get the cow & get it traded though.

If I wanted to kill a plant, I'd put it in peat. But I wanted to stop doing that, so I stopped doing that. Wasn't working for me.

Hats off & cheers to those who have good results using these things, good job.

    Bookmark   June 12, 2012 at 5:58PM
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prestons_garden(9B SZ 22 HZ 6 SoCal)

Are you in the Marketing Department for MG??

"Everything is growing so fast that I cant eat it quick enough."

"Everything we have is growing in MGMC, every flower, every vegetable, a small sweet bay tree, and all doing very well."

If not, you should.


    Bookmark   June 12, 2012 at 6:53PM
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""Magic moisture crystals ""

There aren't any of those in it, it uses "Composted Coconut Husk" to hold water, although it doesn't seem to work all that well for that because I water heavily every single day unless it just rained pretty hard. Water drains right out of it very well.

""Are you in the Marketing Department for MG""

Nope, just a retired Marine Biologist stating a fact is all.
I buy the MGMC mainly because I can buy it at Costco and it is the cheapest good mix I can buy.
It cost $9.99 for 55 quarts.
If I could buy something else just as good cheaper I would in a heartbeat.

But when I see people slamming something that I am using and having absolutely NONE of the problems listed I feel I should chime in and say so.
There is certainly no reason for any "Warning".

I can see amending it a bit to match whatever the needs are of the particular plant you are putting in it, to match the Ph or nutrient requirements, but to say it will basically kill your plants is rubbish and simply not a factual statement. There is nothing wrong with at all.

    Bookmark   June 12, 2012 at 7:16PM
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tapla (mid-MI z5b-6a)

After I discovered how much easier it is to grow in a fast-draining, well-aerated medium, I left heavy, water-retentive soils based on peat and other fine particulates in the rearview & never looked back.

Whether a grower can or can't grow well in any particular soil has no bearing on the evidence; that being that an extremely high % of growers arriving at this forum with plant health problems are using heavy soils, like Miracle-Gro and similar, and the problems are either directly related to water-retention and lack of aeration, or resultant of diminished vitality and impaired metabolism that results from that water retention. That too is a fact.

No one denies that you can grow healthy plants in Miracle-Gro soils and similar, only that it's more difficult and the margin for error significantly reduced. Heavy soils that support excessive amounts of perched water also limit the probability that plants could grow as close as possible to their genetic potential. Each time the lower reaches of the container becomes saturated, roots begin to die. The longer the duration of the saturation, the greater the volume of roots that die, and the larger the roots. When sufficient air returns to the soil between irrigations, roots can then begin to regenerate. This cyclic death and regeneration of roots steals valuable energy that might have gone to more flowers/fruit/bio-mass, so these heavy soils can be very expensive in terms of energy outlay.

I suspect that some of the problem the original poster had might have been related to using plants with a congested root system & not breaking up the roots. I literally rip the bottom half of the roots off, then tease the roots away from the sides of the root ball with a nylon tool I made.

The heat referred to is most likely not from an extraneous source, like passive solar gain. More likely it's a result of the ongoing composting process - like a hot compost pile. Using ingredients in a soil that break down quickly, especially if you add a measure of N, can easily raise soil temperatures 10-30* above what they would normally be, enough to have serious consequences.


    Bookmark   June 12, 2012 at 8:13PM
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I fail to see how peat, coconut fiber and compost is considered "heavy".
Regular top soil like you just dig up in your yard is heavy.

potting mix is pretty damn light, I can shove my hand right on down to the bottom of the pot with just a couple of twist.
When I run about 2 gallons of water on the top it drains right out the bottom like a kitchen sink, how much faster draining can it be than that?

Problems people have with light potting mixes like MG are because lack of drainage thus water retention.
Anything lighter than MG or what ever type of peat and compost potting mix you may as well go Hydroponic.

The original poster had problems due to not breaking up the root ball and not properly saturating the growing medium.

Just curious what would you consider lighter and faster draining and better aerated?
I will change to that magical substance next year, or at least amend what I already have with it.
I am not going to wing out about $160 worth of potting mix, but will certainly amend it as needed if something proves to be better.

    Bookmark   June 13, 2012 at 12:37PM
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Ahhh I just read part of an old post "Container soils water retention etc" which makes perfect sense and I agree.

The perched water table will be there with the smaller particles, which is why I only grow in very large pots of 15+ gallons with excellent drainage, thus the roots on my plants are larger before they even reach the last few inches of perched water than they would be in a smaller pot with large particles and perlite even if it has zero perched water. Plus I just plain prefer larger pots and bigger root systems no matter the medium.

I may buy a large bag or two of Pine Bark Fines and a bag of large Perlite next year to amend the mix I already have next year. I always lose some soil over the year after pulling dead plants etc, so will replace that with the pine Bark and Perlite just to get a bit better aeration.
But so far large pots with excellent drainage using potting mix and manure works just fine.

    Bookmark   June 13, 2012 at 1:17PM
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greenman28 NorCal 7b/8a

Miracle Grow is "soft" and "fluffy" on the hands, but that shouldn't be confused with "light."
A "heavy" soil as discussed here is not the mass/weight, but the density of fine particulate
and the resulting slow drainage and lack of aeration once saturated.

Unless one grows in very large containers (which are essentially mini raised beds),
container gardening is much closer to hydroponic gardening than in-ground gardening.


    Bookmark   June 13, 2012 at 3:02PM
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Okay first, your plants are gorgeous Nunyabiz. I get similar yields, but our disease pressure and excessive heat make things look less pretty by the middle of the summer. Also, I want a veg trug, whatever it is.

Anyway - I started a couple smaller pots with MGMC, and had some minor problems (which I now believe had more to do with what I was growing than the soil mix). Around April, I made my own 5:1:1 with composted pine bark and it worked fantastic.

This year, I couldn't find composted pine bark. But I noticed when emptying out last years MGMC pots into my raised beds, that it really hadn't collapsed / decomposed much. Even at the bottom of the pot, the mix was still surprisingly coarse.

So I bought some MGMC and sifted through it with my hands. In Texas at least, it appears the product is mostly composted pine bark. This makes sense, considering East Texas produces a huge amount of the stuff, and peat is considerably more expensive to ship in from Canada. Obviously it also includes pH adjustment (probably dolomitic lime, ash, or something like that), detergent treated composted coir, and some peat. So, I decided to try using MGMC as both the pine bark fines and peat component of 5:1:1. I guesstimate the measurements, and leaned heavily toward extra perlite (I have a lot of it). Nothing was screened or otherwise modified.

I used clear plastic cups to test for perched water. Nadda. Admittedly this is when the stuff is still new and fluffy, but I wasn't gentle with the watering at all.

Everything I've put in the mix has done great so far. It's a LOT, lot more expensive than last year, but I was getting desperate.

Just yesterday I finally found bark of the right consistency, though I'm not sure if it's already partially composted or not.. we'll see. $2.50 a bag. I'm going to use it to fill some very large planter boxes I made for containerized watermelon... 55 gallons. If I had to do that with MGMC, I'd probably cry.

Let me also add the caveat that it's very hot here. I have to water most all of my pots everyday, even though they're quite large. That's mostly because the plants in them are quite large, so they use up all the water everyday.

    Bookmark   June 13, 2012 at 8:03PM
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One last comment... I looked up the veg trug. It's really pleasing aesthetically, but I'd be pining for the extra root space that the manger-style shape eliminates. I also don't mind getting on the ground. But..

The inverted triangle cross section of the container is pretty much *ideal* as far as minimizing perched water. Even if the PWT was high, it would take up a much smaller volume of soil than in a regular container. I wonder if that was part of the design rationale?

    Bookmark   June 13, 2012 at 10:21PM
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thanks, yeah the MGMC I get here in NC looks to me to have quite a bit if pine bark also. Buying it from Costco it is the cheapest already made potting mix I can buy.
Vegtrug took 7 full 55 Quart bags.

The shape of the Vegtrug seems ideal with an amazing amount of soil right up to the edges. Even the very edge is 6 1/2 to 7" deep and drops off quickly so plants on the edge still have tons of root space.
Not only does the shape help the PWT but also the "Liner" you put in it wicks water out of the soil.

Only thing I would change about it is I would have made the covers taller, like at least 3 feet tall.

For what I grow in it, Lettuce, Herbs, Bok Choy etc it is perfect. I should be able to grow Lettuce all year now with the Greenhouse cover.

We get probably about the same Heat, Humidity and Disease pressure here in NC, plus we get the full 7 plagues of every kind of insect known to man.
That is why most everything I have is covered and next year will be better covered.
The Vegtrug obviously is best, but I am going to make my Tomato corner much more solid and covered next year.
I just have bird net over it which helps for birds of course but also at least helps keep the horn worm moths off of them.
Unfortunately I didn't make the netting tall enough this year, the plants grew taller than they were supposed to get so are growing up to and trying to grow through the netting which will give the moths a place to land on them.

I am going to go with white bug netting next year just like the Vegtrug over a solid frame of plastic coated steel poles with PVC connectors and pipe connecting the tops and making a frame work for the netting.
Depending on how well these Dwarf Tomatoes I just planted 7 days ago do I may grow nothing but Dwarfs next year which are only supposed to get a maximum of 3 feet tall but still produce full sized large Heirloom type tomatoes.
They should be easier to manage, produce nice fruit.

I also water my tomatoes and the bell pepper everyday as they drink so much in the heat and the pots drain very well.
The Vegtrug has such a huge amount of soil and everything is so thick in it its like a jungle so the soil stays moist for several days. I give them a quick spray on really hot days and a good drink maybe twice a week at most.

    Bookmark   June 14, 2012 at 10:13AM
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Here are the Dwarfs 7 days ago minutes after potting.

and today, 3 of those 7 days were were rainy and cloudy.

    Bookmark   June 14, 2012 at 10:21AM
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dickiefickle(5B Dousman,Wi.)

People overwater their plants and then blame the MGMC.
If you have problems you may have created them .
Many people who state problems also mixed in other additives and still blame the MGMC

    Bookmark   June 16, 2012 at 5:19AM
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chuck(Z10,SW FL)

Wonderful series. Kind of reminds me of creation/evolution debates.

Large container users may benifit from having some 1/2 inch perforated pvc pipes sunk down into their containers (caps on the bottoms). Cut them off an inch or two above the soil level and put some unglued pipe caps on the top of them so that they can be uncapped and used to deep water specific areas from time to time without having to flood the surface too much. If the container should ever become totaly flooded from a storm, a smaller diameter hose can be lowered down into the pipes to siphon or pump out some of the excess water. Having the ability to bottom water specific areas may promote less congested root systems when the large planter contains a lot of plants. It may eliminate dry pockets or excessivly wet areas. I would probably drill the 1/2 inch pipe about every two inches with 1/8 inch hole on two sides.

This is what I plan to try doing with some 55 gallon plastic barrels I am going to plant potatoes in. I am currently using a mix very simular to miricle grow in 1/2 of a barrel, and will be adding more mix as the plants grow and using the perforated pipes to control the ammount of water delivered to the different levels rather than flooding the top to get water to the lower levels.

I plan to use whole barrels instead of half barrels next, and found this particular thread very helpful.

    Bookmark   June 16, 2012 at 6:42AM
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brandkb(10b Los Angeles)

Even though this is an old thread I just picked up up some of this for my dracaenas and a sweet basil plant I repotted. We'll see!

    Bookmark   June 5, 2013 at 9:13PM
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I've had mixed success with MGMC potting mix. After moving to AZ to be near my aging parents I decided to start a container garden in my backyard. I thought herbs would be the easiest way to start and in March I bought a variety of herbs and potted them in self-watering pots. They grew at an astounding rate (especially the Basil). After a couple of weeks I decided to expand by getting larger pots and buying a variety of Peppers and Eggplant.
In addition to the Basil (and Mint) loving the MGMC soil, it seems like the Eggplant loves it as well. I was a little worried that the Eggplant did not seem to grow very much in April, but when the night temperatures consistently started getting over 60 degrees in May, it started taking off and flowering/fruiting. Because of the MGMC I only have to water them every other day at most, even when the temperatures hit 112 degrees. And they are producing quite nicely.
The problem seems to be with the Peppers. I found that Peppers don't like "wet feet" and the combination of the water retention in MGMC and watering from the bottom with the self-watering pots was not good for the plants. When they started wilting AFTER watering I realized I was drowning them and the roots were rotting. I lost a couple of Pepper plants (the Bell Peppers) although the smaller hot pepper plants seem to be slowly recovering. And all this energy they are using to recover obviously makes pepper production a no-go.
Next year I will forego the MGMC for pepper plants (I kinda have to keep the self-watering pots due to the expense but I no longer water from the bottom with Peppers), but will continue to use it for herbs and eggplant.

    Bookmark   June 15, 2013 at 5:46PM
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brandkb(10b Los Angeles)

MGMC would probably not be good for any/all self-watering pots. They make special mixes specifically for self-watering pots and planters, too. I think the EarthBox website has a list of "approved" potting mixes that work with their self-watering kit, many of which are available at your local home improvement store.

I like ProMix a lot for my SW pots. Depending on what's being planted, I throw in some additional domolite as well. For almost everything else that's potted I use the MGMC.

    Bookmark   June 15, 2013 at 6:14PM
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Yeah, I'd never use MGMC for a "self-watering" pots. There's too many things that can go wrong. The few instances in which I've used such pots, I use the supremely well-drained gritty mix. Water slowly/weakly wicks through the turface or diatomaceous earth in the mix, but without creating a perched water table. This allows me to use the gritty mix indoors without have to water every day.

    Bookmark   June 16, 2013 at 10:20AM
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