Container Mix...mix your own

[Ed of Somis]

I have been studying what makes a good container mix...and there sure are many recipes! One thing is critical: drainage. Having a container that is muck on the bottom 4 inches smothers the plant and leads to death. Some people think putting gravel, glass, or even broken pottery around the holes helps. It is not true (seems like it should help...huh?). I will not get into the details and science behind why this happens...just know it does. We all have pulled out "mucky" plants that were dying....right? Creating a mix that is "free draining" simply involves eliminating small particles that plug up the mix. Adding larger particles like perlite, pine bark, gravel, etc....does not help a mix with small particles (like garden soil). How many bb's does it take to make pudding drain??? You get it....right? Adding a wick that is in the bottom of the mix and extends out the bottom hole is a great answer. Simply explained...the cohesive tension shared by the wick and the mix "fools" the mix into "thinking" the pot is deeper. Thus, perched water continues to drain. Not the scientific explanation...but you get it.
Today I planted many containers for my tomatoes using differing amounts of: pine bark (orchid bark), perlite, compost, amend, peat moss, and palm/cactus potting mix. I wicked most of my pots, as well.
Whatever you do...do not use MiracleGro "Moisture Control". It makes the muck factor worse (maybe for hanging baskets I suppose). Happy Spring!

[rnewste]

Ed,

What ratios of each did you settle on?

Raybo

[aconite]

Someone's been reading Tapla'a articles i see

[RootLoops]

my mother in law does the gravel in the bottom thing. she kills me she'll get a bucket with no holes in the bottom, fill it with a few inches of gravel, dig some dirt from the yard, plant something, and then spend the rest of the year complaining about how it wouldn't grow and that "all those plant companies are rip-offs". i used to tell her she had to have holes and good dirt but after a while i just gave up.

i would also like a good homemade container recipe i'll be checking this thread!

[Cole_Robbie]

I think there are three aspects to a mix - aeration, moisture retention, and organic matter/fertilizer. Perlite is almost always used for aeration because it is cheap. Moisture retention can be vermiculite, peat, or coir. Then the last element is where everyone seems to have their own recipe. Worm castings are probably one of the best ideas, but they are ungodly expensive. I bought some mushroom compost this year that I am going to use - it looks like black dirt, just like worm castings. I think any sort of compost would work; it depends on your budget. I like to mix in a little high-P guano and greensand as slow-working organic fertilizers. I also cheat and use Osmocote, too. (not the high-N, though, read the label) It's a pelleted time-release chemical fert.

My mix this year is going to be 7 parts perlite, 6 parts peat-based pro mix, and 5 parts mushroom compost/organic fertilizers. I also add a little mycogrow from fungi perfecti. I tend to add some sort of fertilizer at every watering, even if it is only a bit of alaskan fish, kelp, molasses, or epsom salt. When the plant is fruiting, I give it some of the two fertilizers I use in the fertilizer injector, calcium nitrate and another that is 4-18-38. Earth Juice sells a high-K organic product called "Meta-K" that would do the same thing for anyone trying to stay organic.

[Ed of Somis]

The University of Calif. and many other organizations have great literature/info regarding this subject of soil mixes. Also, there is info online with the "other" tomato site and the "other" gardening site. Trial-and-error is my best teacher. Cole has some good ideas above....As far as ratios...I think it is really NOT an exact science because of the many variables (ie: crop grown, weather, locale, available sun hours, etc). Many products like perlite and pine bark appear to simply be "aerification type fillers"...their biggest value is really to provide an area that allows the roots to grab water and nutrients within it's structure. This principle is where products like "MiracleGro Moisture Control" goes too far. The polymer ball-like structures retain too much moisture for most container applications, and the plants do not have the water/nutrients available 24/7...if you know what I mean. PS (added later) We have not scratched the surface as to nutrients for containers. Again, Cole (above) has brought some good ideas to the table. I would recommend learning exactly what a "complete" fertilizer is. Trace elements added are of most importance when container growing.

[ScottinAtlanta]

Tania published a great container mix recipe a few months ago. I can't find it now - but perhaps she can publish it again.

[aconite]

when someone asks about how to prepare a container mix, usually with the idea that there absolutely MUST be some compost or similar small particle component, i always advise to first make about half a liter of whatever they want to use and put it into a completely see through plastic cup, with holes in the bottom. then to let through a couple of liters of water and observe what happens.
this will nicely illustrate what Ed wrote above: "How many bb's does it take to make pudding drain??". The more water you let through (which simulates the waterings during the growing season), the more you will see your dusty particle component sink to the bottom and clog the container. it will also raise the perched water table in the cup, and with it create anaerobic conditions in the bottom. A particularly bad combination is compost and perlite, because perlite floats and moves to the top of the container very fast, but it happens that sometimes people only have access to perlite.
there is much more to this, but this simple experiment usually gets people thinking and tinkering with their mix until they see satisfactory water movement in their test cup.

there is one beautiful article that gives a very good understanding of how water behaves in container media, i always link it in posts like these, take a look it, it isn't long or hard to read:
http://oregonstate.edu/dept/nursery-...roperties.html

there is also a sort of easy solution if you can find this material, dr. Mark Dimmitt wrote an article about using coconut husk chunks (NOT coco peat, that stuff is awful) as a universal container media: http://www.tucsoncactus.org/html/gro...June_2013.html
sadly i can't find coco chunks anywhere near me and i've had no success finding a source online in the EU who can ship for even a relatively decent price (if any of you from the EU know of one please please let me know?), but you guys in the US should be able to get this.

[zipcode]

I see on UK forums they mostly use compost over there in containers and they seem to have jolly good production. It probably depends what exactly is in the compost I guess, but I wouldn't dismiss it as something terrible that should never be used.
I myself have used flower mix, which is pretty much peat (preferably coarser), and I've been happy.

[Ed of Somis]

lively conversation here...and many excellent points to consider. Glad I started this thread! It really is an important subject for the container grower.

[Sodak]

I use homemade "Mel's mix" from the square foot gardening guru.
I found sq ft too jungle like but like the mix.
Basically 1/3 of each of the following:
Perlite
Peat Moss
Compost manure - differing manufacturers of this.

Dump similar amounts of each by volume on a tarp and flip back and forth several times. Then load your pots or raised beds.
I use Texas Tomato food with it and it works well.

[Ed of Somis]

I have tried to mix similar products as above. However, my compressed bales of peat moss are just impossible to separate and take apart.

[peppero]

does anyone have any thought/experience about using nut shells such as peanut, almond, pecan etc

jon

[squirrel789]

I did a lot of research on Tapla's now-famous 5-1-1 or perhaps 3-1-1 mixture, and I am starting to understand why this can be good for container gardens and it really makes a LOT of sense... for next year.

I am wondering if there is a post-planting fix I can devise for this year. I'm using a very large container (170 gallons) as described in the "trough" thread here in the container section. My mix was compost, peat, and vermiculite. I thought I was doing the right thing by adding nutrients and water retention for our very hot and drought-prone MO summers. A similar mixture to what I use has been suggested elsewhere, and without realizing it, I definitely made a mixture that I fear retains too much moisture. I'd like to maximize the production/container-space ratio, and I guess I'm looking for all the info I can get to make it the best it can be.

Despite drilling tons of holes, I now know I created a mixture that likely retains too much water and I am concerned about the PWT and the negative effect it could have on the health of my roots, or their growth. I planted close together as an experiment (newbie) hoping that the 170 gallon growing medium volume and a good, comprehensive fertilizer would allow for the plants to succeed. I have used some TTF, and want to use more, but am now afraid of over saturating the soil. The troughs are on 5" heavy-duty castors so I can move them around the patio if need be for more sun, shade, protection, etc. However, what I thought was a good idea turns out to make the PWT issue even worse since it raises the containers off the ground, which might have helped wick way excess moisture. I also plan to keep plants pruned to 2 vines each and given lots of vertical space to grow since they are all indeterminate.

So, is it worthwhile or recommended to try to drill a few holes in the sides of the tank near the bottom (where I presume the PWT to be) and perhaps insert some sort of wicking ropes or material deep into the center of the mix and string it out to the patio or ground (container is on a patio, but the ground isn't that far away). Perhaps this would help decrease/eliminate the PWT? Might this work, and if so, does anyone think it would be beneficial?

More to the point, is it necessary? Will the PWT actually help during hot summers, or will it just encourage root growth into this area when the plant is drier and wants more moisture. Will these roots later be drowned and rot when the container is watered again, re-establishing the PWT?. Right now the plants are growing very well and seriously look bigger every morning. I am worried that the mix I used, and hence the drainage and PWT issues, could cause the plants serious problems later on and they will fail, or produce poorly. I know I said this garden was an experiment, but I'd really rather it not fail

Before I learned last night what a PWT is, though I certainly don't claim to fully understand how it functions, I thought squirrels would be my biggest problem Now I wonder if my tomatoes have a good chance of being healthy at all.

As I often do, I could be over thinking the situation, or just being paranoid.

I'd truly appreciate any feedback anyone has to offer.

[ChristinaJo]

Ed, I tried to look up Tania's post and found this. But I think it was for seed starting...
I copied and pasted into my "notes". Hope it helps.


It used to be Promix HP for me. Not anymore. It was a great mix for seed starting, but pepper seedlings will not thrive in it.

We now make a mix from 75% coco coir and 25% perlite. Works so much better for pepper seedlings! When potting up, we just add 50% compost.