I am new here and am interested in growing in containers. From growing other things in containers I know that the medium is critical and you just cant put "whatever" into the container- what might be good for one plant might not be good for another, I would like to hear what folks are using in larger containers (7 , 10 , & 15 gl size ) for their mixes
Thanks!

Welcome to the Junction, @rusty !

There's a whole section here, about half way down the Home menu, where you'll find a LOT of information on that.

containers-earthboxes-and-raised-beds.html

Thanks Dawg

Welcome @rusty to the Junction.

For my 25 gal containers I am using an old recycled 511 mix I made years ago. If I remember correctly it was bark fines, peat and perlite. Over the years I have added peat and other miscellaneous things such as crushed egg shells, spent tea leaves and compost. I also have switched to using granular DE (Diatomaceous Earth)...Floor Dry from AutoZone instead of perlite. But primarily I add Kellogg's Patio Plus Premium Outdoor Organic Potting Mix. I fertilize with Garden Tone organic fertilizer. I use the same mix for my peppers, zucchini and anything else I decide to plant.
https://www.homedepot.com/p/Kellogg-Gar ... /100160888

I use the same Kellogg's Patio Mix in all my different sized containers, 5 gal thru 25 gal. I also use the Patio Mix as-is. For small pots I run it through a sieve to get the big stuff out.

Cheap soilless potting mix has worked well so long as fertilizer, either in liquid form or granules is added every week or ten days. After the initial higher nitrogen addition, a balanced formula seems to work best. Side dressing with 12-12-12 or 10-10-10 every so often keeps containers doing very well even with the cheap potting mix. Its the nutrients not the soil.

I made a large batch of potting mix in 2021 for all of my 5G, 20G and 30G containers.

It was a 3:2:1 ratio by volume of leaf compost:peat moss:perlite+vermiculite. Originally I was going for a 2:2:1, but I had a lot of compost and kept adding more until I liked the consistency as I thought there was too much peat moss in the mix (just visually). So, depending on what your compost looks like the ratio could vary. You could just use perlite instead of the perlite+vermiculite as well.

To that, I add:
1 tablespoon of dolomite lime per gallon of PEAT MOSS used in the mix
1 cup of granular organic fertilizer (chicken manure-based, 5-3-2 or 4-6-8 or 5-4-3 depending on what I buy) per 10 gallons of total mix

I add more fertilizer to the planting hole, and if I have worm castings I add that too (I don't buy it anymore though).

I re-use it each year. I dump out ~100G on a tarp and top it up with the a mix of compost/manure, peat moss, lime and organic fertilizer. I do that just visually.

In 2022 I mixed up another smaller batch, but used a pre-made potting mix (Sungro Sunshine Mix#4, similar to ProMix HP - it's just peat moss, lime and perlite) because I had some and added some sheep compost and organic fert to that. I mixed it all up about 1 month ahead, with the hope it helps to continue to break down the manure if needed.

I have not tested the potting mix for NPK or pH, but am going to do that this year.

Mix outside, be upwind (if any) of the mix, and wear a mask. Things like vermiculite, banned in some places, are nasty if breathed in.

I use the same mix for all size of containers, and I reuse it each year with additions. I have ended up with some perlite because it's helpful for mixes used in the house, so that ends up cycled out to the greenhouse too. Mine is compost and peat based, but the best thing I have added on the tip from bjbebs has been well rotted horse manure. This has really helped with moisture retention, and I'm able to grow better in smaller containers with less water stress. Not adding any peat any more, but varying the type of compost (bought stuff is peaty; garden is more moist and rich).
Also I've started to do more reconditioning of the mix in off season. Empty smaller containers with roots into larger tubs; add kelp and lime and chicken pellets, and fresh compost or aged horse manure, water it. Give the worms time to convert the organic matter. I still add ferts at planting time, but the overall condition is rich and bioavailable, meaning I don't have to worry too much about extra feeding during the short season we have.

For me, the key is keeping any peat away from the soil surface, where contact with air dries it out quickly. Whether it's having two different soil mixes, with the top one having little peat, or one mix then later covered with a layer of mulch, anything to help retain more moisture.

I have used ProMix BX for the last 5 yrs. for my tomatoes and peppers. 15 gal grow bags for tomatoes & 7 gal. grow bags for peppers with outstanding results. I use it for 3 yrs. then discard it. I fertilize with Master Blend.


Dan

Tormato wrote: ↑Sun Feb 05, 2023 1:11 pm Mix outside, be upwind (if any) of the mix, and wear a mask. Things like vermiculite, banned in some places, are nasty if breathed in.

This is good advice for working with soils, especially if you're doing it frequently (like occupationally) or in a confined area. Keeping the mix damp also is advised.

Just want to clarify, vermiculite mined and sold these days most likely is not any more dangerous than any other soils and soil additives/components. The danger came from asbestos contamination of vermiculite mined at the Libby Mine in Montana, which closed in 1990. Now that the Libby Mine is no longer the source, vermiculite is not generally expected to contain asbestos, and without asbestos, vermiculite poses the same health threats as any other nuisance dust.

The US EPA says: "Vermiculite ores from some sources have been found to contain asbestos minerals but asbestos is not intrinsic to vermiculite and only a few ore bodies have been found to contain more than tiny trace amounts. See: http://www.epa.gov/asbestos/pubs/verm.html"

The main sources of vermiculite now are the Eastern US (Virginia and South Carolina), South Africa, Russia, China and Brazil. All vermiculite mines now are regularly tested for asbestos (at least, they're supposed to be).

Here's what a representative Material Safety Data Sheet says:
Summary: Vermiculite is a naturally occurring, mica-type mineral. This product does
not contain asbestos at the level of detection of the analytical methods employed.
No serious health risks have been found resulting from exposure to vermiculite that
is free from asbestos and crystalline. OSHA has classified vermiculite as a
Particulate Not Otherwise Regulated (PNOR), which has the same Permissible Exposure
Limit (PEL)as that used for nuisance and inert dusts. Dust levels should be
maintained below the OSHA PEL for PNORs and respirators used when airborne dust is
present. Excessive inhalation over long periods of time may cause harmful
irritation. Vermiculite is considered a nuisance dust by ACGIH.
Medical conditions which may be aggravated: pre-existing upper respiratory and lung
disease such as, but not limited to bronchitis, emphysema and asthma.
Target Organs: Lungs, eyes.
Route of Entry: Inhalation, dust contact with eyes.
Acute Health Effects: Transitory upper respiratory irritant. May cause coughing or
throat irritation.
Chronic Health Effects: Excessive inhalation of any mineral dust can overload the
lung clearance mechanism.

I don't in any way mean to downplay the dangers of asbestos or the terrible human health toll of the Libby Mine. I worked in toxic chemical regulation for many years, so I take this stuff seriously.

Seven Bends wrote: ↑Sun Feb 05, 2023 4:33 pm

Tormato wrote: ↑Sun Feb 05, 2023 1:11 pm Mix outside, be upwind (if any) of the mix, and wear a mask. Things like vermiculite, banned in some places, are nasty if breathed in.

This is good advice for working with soils, especially if you're doing it frequently (like occupationally) or in a confined area. Keeping the mix damp also is advised.

Just want to clarify, vermiculite mined and sold these days most likely is not any more dangerous than any other soils and soil additives/components. The danger came from asbestos contamination of vermiculite mined at the Libby Mine in Montana, which closed in 1990. Now that the Libby Mine is no longer the source, vermiculite is not generally expected to contain asbestos, and without asbestos, vermiculite poses the same health threats as any other nuisance dust.

The US EPA says: "Vermiculite ores from some sources have been found to contain asbestos minerals but asbestos is not intrinsic to vermiculite and only a few ore bodies have been found to contain more than tiny trace amounts. See: http://www.epa.gov/asbestos/pubs/verm.html"

The main sources of vermiculite now are the Eastern US (Virginia and South Carolina), South Africa, Russia, China and Brazil. All vermiculite mines now are regularly tested for asbestos (at least, they're supposed to be).

Here's what a representative Material Safety Data Sheet says:
Summary: Vermiculite is a naturally occurring, mica-type mineral. This product does
not contain asbestos at the level of detection of the analytical methods employed.
No serious health risks have been found resulting from exposure to vermiculite that
is free from asbestos and crystalline. OSHA has classified vermiculite as a
Particulate Not Otherwise Regulated (PNOR), which has the same Permissible Exposure
Limit (PEL)as that used for nuisance and inert dusts. Dust levels should be
maintained below the OSHA PEL for PNORs and respirators used when airborne dust is
present. Excessive inhalation over long periods of time may cause harmful
irritation. Vermiculite is considered a nuisance dust by ACGIH.
Medical conditions which may be aggravated: pre-existing upper respiratory and lung
disease such as, but not limited to bronchitis, emphysema and asthma.
Target Organs: Lungs, eyes.
Route of Entry: Inhalation, dust contact with eyes.
Acute Health Effects: Transitory upper respiratory irritant. May cause coughing or
throat irritation.
Chronic Health Effects: Excessive inhalation of any mineral dust can overload the
lung clearance mechanism.

I don't in any way mean to downplay the dangers of asbestos or the terrible human health toll of the Libby Mine. I worked in toxic chemical regulation for many years, so I take this stuff seriously.

My state was very late to the game. They banned it about 5 years ago, and then lifted the ban a couple of years ago. With no information on it, like you supplied, I think retailers are still wary of stocking it, here.

I am usually weary of having to much moisture- scared of root rot, to heavy where roots wont want to grow out in. I am more of a perlite / porous type of fella versus vermiculite. Lots of good info posted here folks, finding this is a great place.

I like the outside, upwind, masked advice even for perlite. That fine dust is truly nasty enough, whatever it's made of.
I have a container with a lid that I make my potting mix in. Out in the greenhouse is as close to outside as I can get in winter.
I put some bagged compost (which is damp) into the container first, then pour some dusty perlite on top and slam the lid until it settles down. And then I make sure it has all been dampened with compost before adding more.
Just lately I've been adding chicken pellets to the mix and leaving overnight so it disintegrates and can be dispersed throughout, as a mix for potted vegetables in the house. It definitely beefs up the potting mix... (hmmm mixed barnyard metaphors? )
The damp tropical climate is special @rusty and for sure you'll find your best tricks from our Florida and other southern growers, who have struggled with the same issues and tried it all!

Bower- thanks for the tips
I have never heard of chicken pellets before-- Alphalpha pellets yes but not checken pellets
Will have to do a www search on those

Pro mix, perlite, and a handful of worm castings. Peppers and tomatoes also get osmocote.

I don't know where you are, so don't know if you can get it, but I use Vermont Compost's Fort Vee for everything. They also have a Fort Light with perlite to make it lighter if you need to move big containers. Both have wonderful well balanced fertility, and, as far as I can tell, both are great for everything except maybe orchids.

Lots of GREAT feedback
One of the best forums I am on!!!!

It depends on the climate. If you're in a dry climate you want something that holds more moisture that if in a humid climate.
Basically peat or coconut coir, compost, and perlite or vermiculite. Then whatever amendments you want to add.

Late to party post !! But I use 3 to 5 gallon buckets I’m switching to grow bags this season same size easy for me to move!! I’ve used masterblend and wormcasting , indoor garden peppers have worn casting and I’m trying a new fertilizer for tomatoes jacks!! Can’t tell how it’s going yet for tomatoes just do to having to restart my inside situation again !!peppers are thriving