i am a beginner in the plant nursery business and as such my budget is limited. How can I make a huge quantity of cheap but a good quality potting soil?

coconut husks make a quality but inexpensive potting soil called "coir" - ground coconut husk ....

deepsouth said: coconut husks make a quality but inexpensive potting soil called "coir" - ground coconut husk ....

Should something be added to the coir or can plants be grown using only coir?

Coir is substitute for peat moss (and can be used alone - or as a soil additive) - coir is what I put in potting mix for caudex plants, like: adeniums, Mexican yam...pony tail palm - along with chunky: sand, rocks, pebbles, perlite, bulk charcoal, sometimes bark and/or shredded bark

coir is available in pressed bricks of various sizes - a 10 lb brick will expand 5 to 7 times (2.5 cubic feet) when expanded in 12 gallons of water

@Phurpa Need more information. Are you actually starting a nursery business?

Your choice of potting media has a large impact on what kind of opportunity your plants will have to realize as much of their genetic potential as possible. The easiest potting media to grow in and the the type of media that allows your plant to realize as much of its potential as possible will be one that holds very little (or none at all) excess water. Excess water (aka 'perched water') is water held between soil particles where it displaces air and affects root function or health. Excess water in the medium can rob your plant of 100% of its growth potential because it kills fine roots via oxygen deprivation. Death of the plant's finest roots, the ones that do all the plant's heavy lifting, cause the plant's chemical messengers to inform plant central to stop all top growth until the plant has replaced/regenerated a volume of lost roots that makes the root system capable of adding new top growth.

The size of the particles that make up the grow medium primarily determines how water-retentive a medium is. Coir, is very fine. As such, it holds a LOT of excess water. Also, commercial ops that water from the top usually limit coir to less than 10% of a medium because coir compacts very easily which makes it even MORE water retentive. So physically, coir is quite different from peat. It is also quite different chemically. Using coir as the primary component of container media virtually eliminates lime or dolomitic lime as a possible Ca source because of coir's high pH (6+). Gypsum should be used as a Ca source, which eliminates coir's low S content. All coir products are very high in K, very low in Ca, and have a potentially high Mn content, which can interfere with the uptake of Fe. Several studies have also shown that the significant presence of phenolic allelochemicals (toxic to a notable % of plants) in fresh coir can be very problematic for a high % of plants, causing poor growth and reduced yields.

I have no idea what's available where you live insofar as media ingredients are concerned, but I would caution you against using a large fraction of coir in any medium for all the reasons listed. It just can't be considered as a direct replacement for peat.

Personally, I have experimented with coir (and CHCs [coconut husk chips]) several times and been disappointed every time I used it. Even when substituted for peat in a 5:1:1 mix of 5 pine bark, 1 peat, 1 perlite, results were conspicuously sub-par.

Unfortunately, there is no way to amend coir to make it drain well, especially after a few waterings from the top. You cannot start with a large fraction of coir and amend it by adding perlite. If you start with a half jar of coir and fill the rest of the jar with perlite (and mix), you would still have a poorly aerated medium. Reason: as long as there is enough coir to fill all the air spaces between the perlite, aeration will remain poor.

Too, coir's high pH precludes use of dolomite or other liming products, and it's high K content means you'd need to figure out a way to work around that issue as well. All the above is especially true if indeed you are starting a nursery business.

My suggestion would be to see what nursery ops are using for their media. I'm guessing their media will be based on a very large fraction of coarse material, like pine bark, and a small fraction of something finer (peat, boiled rice hulls, possibly a small fraction of coir, and they will be cognizant of the work-arounds coir requires for best results and have them in place.

Below see the 2 types of media I use. Both are based on very large fractions of coarse material adjustable for water retention by varying the volume of fine material they contain. I haven't purchased a commercially prepared medium since about 1980, reason being commercially prepared potting media based on fine materials like peat, coir, compost, composted forest products, sand, topsoil, etc., cannot offer plants an equal opportunity when it comes to realization of their genetic potential.




Al

If you're growing very large quantities (hundreds/thousands) of plants a 50/50 mix of sand and composted shavings or other plant material works. This is the typical mix for commercial nurseries around here.
You can mix in any other components like perlite, coir, rice hulls to change porosity or take advantage of local availability. Keep it to basically 50/50 organic and inorganic materials.

@tapla What exactly do your 2 types of media consist of?

@CalPolygardener What are composted shavings?

The basic mixes are:

5:1:1 mix
5 parts pine bark screened from dust to 3/8" (10mm)
1 part sphagnum peat moss
1 part perlite
dolomite lime

Gritty mix
1 part screened Turface MVP or Allsport
1 part poultry grit (crushed granite or quartzite) screened 1/8 - 3/16" (3.2 - 5mm)
1 part pine bark screened 1/8 - 3/8" (3.2-10mm) OR fir bark 1/8 - 1/4" (3.2 - 6.5mm)

I grow hundreds of woody plants and succulents in the gritty mix, and all else in the 5:1:1 mix.

It should be noted that one can have a number of media components which, if mixed correctly can make almost the perfect soil; yet, the same ingredients can be mixed in such a way that the end product is closer to unusable than usable. The problem with most commercially prepared mixes or custom mixes is that they typically contain too much fine material. If one is to take advantage of the several advantages of a well structured medium (fast drainage and added air porosity), it's essential that the medium has a VERY large fraction (about 80%) of coarse ingredients. Whether or not it's mineral or organic doesn't matter. When a medium is structured such that there is enough fine material to fill all the spaces between the coarse ingredients, you're growing in a medium with drainage/aeration properties which are essentially that of the finest materials. If you have a jar of marbles with huge air spaces between the marbles and you add enough peat or coir to fill all the spaces between the marbles, you're growing in a medium with the same properties as the peat/coir.

Al

Composted shavings are wood shavings from a lumber yard that have been composted for several months. It could be any kind of wood product, such as wooden shipping pallets, that has been reduced to shavings or small chips that have been composted for several months.
Due to the high carbon content, it will need additional fertilization especially nitrogen.
These are components that are relatively inexpensive and so are more affordable in large quantities for nursery production. They are best suited for general landscape plants and not for sensitive specialty species.

@tapla The sphagnum peat moss, is that the fluffy kind or the compacted brown kind?

Sphagnum peat moss:


Sphagnum moss:


@Phurpa If you are fortunate enough to have access to pine/ fir/ spruce bark, you would be much better served to use that instead of any form of milled wood chips or sawdust. The sapwood of hardwood trees is very high in cellulose which breaks down quickly and ensures significant immobilization of nitrogen (already mentioned). Heartwood and sapwood don't have nearly as much lignin (a natural polymer that makes woody plants woody) or suberin (another natural polymer often referred to as Mother Nature's water-proofing for plants because of it's ability to resist soil biota's efforts to cleave the hydrocarbon chains that make up the bark. Together, these natural polymers ensure that media made with conifer bark retain their structure far longer than media made from hardwood products or hardwood bark. When it comes to judging how productive a medium will be, the primary considerations are it's structure and it's ability to retain that structure. It's likely you'll use half the volume of a medium based on hardwood products due to soil organisms cleaving the bark's hydrocarbon chains and the carbon gassing off as CO2. Too, media with notable fractions of hardwood products in the mix will be inclined toward a pH high enough to preclude the use of dolomite as a liming agent.

The composting process is exothermic, meaning it gives off heat. If all else is equal, temperatures of roots grown in a sawdust-based medium can be 10-15*F higher (than if the sawdust was conifer bark) due to the accelerated rate at which soil life breaks down the soil particles. While this might not strike some as a serious issue, it IS serious. On those dog days of summer when soil temps are in the 100-110* range, that extra 10-15* can easily be a life/death matter to the plant material you're growing.

If you're going to save a bit of money here and there, I suggest you don't skimp on the soil. Before you can hope for a healthy plant, it's essential that you're able to first keep the root system happy. A good medium also allows you to water correctly w/o concern about over-watering; it makes fertilizing extremely easy; and, it will help you avoid a lot of problems that would otherwise BE problems because of the stress caused by inefficient or infected roots.

Vigor is a genetic trait and speaks more to what the plant's 'potential' might be. Vitality is a measure of how a plant deals with the cultural hand it's been dealt. Almost every plant has the genetic coding it takes to become a wonderful example of the species and cultivar/variety. Whether or not it ever becomes that exemplary specimen depends on how well the grower is able to identify and eliminate stress factors. In fact, it could be said that's our only job.

When growing in containers, you can put two-bit (cheap/ inexpensive) plants in a ten-dollar soil (a structurally stable, well aerated soil) and have a beautiful garden; but, if you put a ten-dollar plant in a two-bit soil the most highly favored outcome is disappointment.

Al

One thing I can tell you about the sawdust/sand mix is that it worked great for roses and fruit trees. For the 7 years I worked there and the previous 25 as well. In summer temps ranging from 80s to 110+. I can't quote you the physics or chemistry, but I can tell you it worked.

Idk what the original poster plans on growing but I'm growing Adenium, succulents, tropical houseplants, a couple of coffee plants (which I'm struggling with) & a few other odds & ends. I'm in Northeastern Illinois, zone 5b where I have to bring everything in for long winters.

I really appreciate y'all sharing your knowledge with me as I really struggle with getting the soil right & truly want my plants to thrive, not just survive.

I think we all get to decide how hard we're willing to strive or how far we're willing to go to achieve excellence in anything we aspire to. We also get to decide if we are willing to stay our additional efforts once we reach a point where the results meet our minimum standard for 'good enough'. "If it's worth doing - it's worth doing right" isn't part of a skillset, it's an attitude, and having that attitude can at varying times be viewed as a virtue or a curse.

I find looking at things from the plant's perspective as opposed to trying to determine what the grower might be thinking is probably the best way to help growers get the most from their growing experience, e.g., telling them what they can do to achieve the best results as opposed to telling them how to avoid effort by settling for mediocrity, or something well short of excellence. I can't stress enough how important media choice is in determining both the quality of the results and the personal satisfaction that comes from doing something, or anything, well.

Telling someone how to achieve the best results ensures the grower knows how to excel, which leaves all the room anyone could ever need to decide on a personal level whether excellence is worth the effort. Providing information that would find the grower falling well short of whatever degree of success (s)he anticipates not only sets the stage for disappointment, it also leaves growers w/o an understanding of how to rise above any limitations imposed by a mediocre medium.

Al

Some info on various planting mixes...
Here is a listing of soil mixes produced by a company here in Oregon for nursery use.
I use their 5F product for most vegetables, annuals, perennials and shrubs from 4"pots to 2 gals. If a plant requires better drainage than this mix provides, I add 10-25% more perlite or pumice depending on the plant variety.
Clicking on each product will get you to a detailed evaluation of all the ingredients.
https://pro-gromixes.com/lands...
as an aside, my most recent purchase of 5F was $71.40/yd. picked up.

Phurpa said: i am a beginner in the plant nursery business

That quote screams "caution" to me!
But to answer your question, you must mix potting soil that meets this description:

attra.ncat.org said: It will have pore space to allow for the retention of both air and water and the rapid growth of roots throughout the media. It will be chemically balanced, with the right pH and nutrients for plant growth – or the ability to retain nutrients that may be added later in a liquid fertilizer. And it will be biologically active, with the microorganisms needed to mineralize organic fertilizers, suppress plant pathogens, and support the health of the plant.
https://attra.ncat.org/publica...

Before you pick up a shovel, ask yourself if you can make that mix described above cheaply and in huge quantities?

We are all beginners at some point, but looking for the cheap way has cost me big in unmarketable nursery product in the past. Learning things like this is the expensive way to learn and might just put you out of business before you get started- Especially if you make a "huge quantity" of a mix that doesn't grow your plants well.

As a fellow beginner in the plant nursery business, I would advise:
1) Seek out the soil needs of the plants you will grow.
2) Realize that locally-sourced materials for your mixes will usually be cheaper due to smaller transportation costs. As an example, in my area in the western U.S., Canadian sphagnum peat and wood byproducts from the local lumber industry are far cheaper than coir that must be shipped to me from the other side of the world. Then, knowing this, apply my point 1, above.
3) Seek local advice from people WHO ARE EXPERIENCED in your area. There are super-smart people here, of course, but your government agricultural & farm agencies and local universities with horticultural or plant science departments are great local sources, generally with a desire to see local businesses succeed. They might help you with testing your soil as well.
Local nurseries can also be helpful- visit them and watch how they work. Learn their secrets.
4) read up on soils from quality sources if you haven't already done so! When you can recite the definition of "humus" (spelled with ONE 'm'-) during casual conversation at the dinner table, you are well on your way. These links are two of my favorites- and the first one gives away a lot of "secret recipes" you've probably already heard about. The second one makes sure you have a rock-solid understanding of - uh- weathered rocks, minerals and humus we call soil?

https://attra.ncat.org/publica...
https://extension.psu.edu/intr...

Try your searches using Google Scholar at
https://scholar.google.com/
to find the more detailed scientific information you need.

Happy researching!