Adjustments to Mel's Mix

I jumped into square foot gardening with my horticulture students this year. We had a hydroponics system that was too automatic for the students to learn much from, so we converted to square foot gardening and now they make all the decisions. They each have 4 square feet.

My concern is that peat moss is hard to get wet when it is allowed to dry out. Much of the compost is similar material with a lot of wood material. We carefully followed the 1/3, 1/3, 1/3 mix. My point is that some times the water just moves around the peat moss even though we mixed it well and there are dry spots. I applied a wetting agent with the water and there still are dry spots after watering the heck out of it.

Wouldn't there be some merit in adding some perlite to the mix to encourage it to take in more water?

Also from past experience mineral soil is a good holder of minerals without having the micro-organisms tying up the nitrogen when the soil is mostly organic. Why not add a small portion of top soil?

What are your thoughts? I know that many may feel it non sacred to change Mel's Mix but...

Victor Noble, Horticulture Teacher, Vale High School, Vale Oregon

Ever thought of using a wetting agent like a quality natural bio degradable liquid soap in the dosing water to wet the peat , or perhaps experiment with the likes of sodium bi carbonate as a wetting agent if you let peat dry out .

Perhaps even trying a slightly acidic addition to the watering dose for after all naturally soft water has dissolved salts in it & it is a penetrator and slightly acidic .

As you'd only need to wet the peat once what I've said might well be an easier option but you will need to do a few growing experiments to prove it out.

Live steam might also be an initiator for water absorbtion if you need to wet loads of peat , once live steamed run cold water through the stuff using a lance & hose

What is mineral soil?

Greetings,

Dry MM is difficult to saturate, no doubt. I'm sure you fluffed your peat before mixing. Mel recommends misting as you are mixing to help reduce dust. That also begins getting the peat wet. I think he suggests (if he doesn't we do!) spraying water on the MM as you are adding it to your box.

It can take all day to properly saturate a box of dry MM. Add water, mix, wait, add, mix, wait,...

Furbalsmom is the only experienced SFGer on the forum who has measured, and posted, the necessary volume of water to properly saturate a basic 4x4x6" box.
It was 19 gallons! Maybe your class could do such an experiment and report back here with your results?

Vnoble, welcome to the forum!
And you are correct, it is somewhat "taboo" to discuss changing/making adjustments to Mel's Mix. Mel's Mix is the Heart and Soul of SFG
We are here to promote the square foot gardening method and Mel's Mix as presented by Mel Bartholomew himself. He spent decades perfecting the method and Mel's Mix. I don't think any of us here are qualified or have enough "expertise" to change that.
Boffer sums it up nicely. It would make a great class experiment to measure out the water and see what you come up with.
Again, welcome aboard and we look forward to your results!

Hi Victor:

This does sound like a great experiment for your students!

As noted, what we promote here on the Forum is Mel's Mix the way Mel teaches.

That being said, I think that if your students find a way that improves SIGNIFICANTLY upon MM, it would be great for your class to correspond directly with the SFG Foundation and Mel Bartholomew and provide them with the results of your research. Mel's a curious sort and the reason he improved upon the "old" method is because of feedback from users of the system.

Regarding your compost, you mention it's comprised mostly of "similar material" and mainly wood material. Of course I would suggest that before you start your experiment, you try to make it a little more "well rounded" with the addition of manures, etc.

Were you thinking of perlite instead of vermiculite, or in addition to it?

Kelly, the definition of mineral soil is: Any soil consisting primarily of mineral (sand, silt and clay) material, rather than organic matter.

Many people balk at having to find 5+ different compost ingredients and then the vermiculite. Personally if I told my students that in addition to jumping through these hoops, that they would need to find ingredients (remember some of them are growing on apartment patios/roofs and don't have access to "mineral soil") and screw up the simple 1/3 equation that they would hang me from the nearest trellis!

As noted in previous posts, we would LOVE to hear about their results.

Welcome!

Kim

vnoble.
I am on the Southern Oregon Coast and will have to look up Vale, OR as I don't know where that is located. I look forward to hearing how your students' SFG progresses.
I found that fluffing the peat moss (I even rubbed it between my gloved hands to break up the clumps) helps the peat moss to rehydrate more easily. Fluffed peat moss has almost twice the volume of baled or compacted peat moss. Fluffing (our scientific word) also allows you to have more equal volume measurements of the three ingredients as specified by Mel in his ALL NEW SQUARE FOOT GARDENING book.

It is important that all the ingredients be well mixed, again so it will be evenly moist and to make sure your compost, vermiculite and peat moss are distributed evenly. I also notice you mentioned wood compost products, if you go back to the home page, on the upper left you will see "hover" In the section there is a great write up on Mel's Mix How Strong is Your Backbone and how important it is to have a mix of at least five different types of good composts.

If you water in each layer of Mel's Mix as it goes into the SFG frame, you avoid having dry spots. If you put in a couple of inches of MM, then water well, by the time the box is filled, the peat in the lower layers has had a chance to fully hydrate and that allows it to soak up additional water easily. Don't let your MM dry out, ever. It becomes hard to rehydrate once it has dried out.

Edited again to add: Found Vale, OR on the far eastern side of OR at the ID border. Wow, much different climate from mine

Hi there Vnoble! I am hapy to see you here and

I am excited that you are doing Square Foot Gardening with your horticulture students, BRAVO!
If you don't yet have the book (2006) it is worth the purchase. In the book Mel does address the issue of perlite, which is a perfectly good substitute for the vermiculite, Mel doesn't use it because he doesn't tolerate the dust well.

I have found the wetting issue as well, but as the season goes on and more organic material (homemade compost) is added to the growing medium the mix in the garden retains more moisture for longer, as it should and as one would expect. Some folks very successfully use drip irrigation systems to retain desired moisture levels of the growing medium.

As to the source of your compost, it is not advisable, as you may well know, to add wood chips into the compost mix, bark is fine though.

As previously stated, the compost portion of the Mel's Mix is recommended to be a mixture of five sources, eg: poultry, cow, horse, crab, seaweed, rabbit, what ever you can find, but really, the diversity of the compost is the key and it IS what gives the mix it's nutritional value.

Mineral soil: Hmm..... well if I was going for the soiless growing mix I would not be adding dirt components. If you are seeing nutritional deficiency signs and symptoms, proper procedure would usually be soil test before adding amendments.

It is kind of exciting that you have students available to you. Perhaps, if I may be so bold as to suggest, this would be a perfect opportunity to allow them to devise their own small scientific research project, revolving around differing ingredients, water retention percentages, pelite vs. vermiculite, nutrient availability to the plants as a result of differing composts, etc.
I am glad you stopped in! I would love to see your student's gardens!

And don't forget the peat substitute coir. I believe there have been comparisons run on water retention of these as well. I attended a SFG session and the teacher used coir instead of peat.

Kay

walshevak wrote:And don't forget the peat substitute coir. I believe there have been comparisons run on water retention of these as well. I attended a SFG session and the teacher used coir instead of peat.

Kay

Coir is a good substitute and a renewable resource just as the north American sphagnum is, but the carbon impact from transporting it and the incredible water usage needed to process it keeps me going back to the native sphagnum.

kelly wrote:What is mineral soil?

Mineral soil is regular soil (sand, silt, and clay with a little oragnic matter. Mels mix has oragnic matter but no sand, silt, or clay unless it was part of the compost that was added.

We put all the peat moss and compost through a 1/4 inch screen so it was well fluffed and the mixing crews did a super job with the rest of the ingredients. The compost was from 5 sources however like the ingredients list on your food labels the ingredients lists are miss leading. If bat guano or worm castings is on the list and it is down the list, you can be sure that there is very little of it in the mixture. We mixed the soil with plenty of moisture at mixing time but allowed it to dry before planting. We will have this same problem during summer and when we start up again next fall after the summer. I thought I had heard some say that organic matter (most of MM) holds more nutrients than mineral soils but this is not exactly true. Organic soils will eventually release minerals that are tied up in the organic matter or the microorganisms that are breaking it down but truth is a mineral soil has the potential for more available nutrients right now. It seems a little of it would be good for the plants in the short run. Other than nitrogen the moneral soil holds most nutrients until the plants need them. I have had many people that do container gardening that use a straight organic mix that they show up with a lot of nutrient deficiencies especially nitrogen.

Furbalsmom wrote: vnoble.
I am on the Southern Oregon Coast and will have to look up Vale, OR as I don't know where that is located. I look forward to hearing how your students' SFG progresses.
I found that fluffing the peat moss (I even rubbed it between my gloved hands to break up the clumps) helps the peat moss to rehydrate more easily. Fluffed peat moss has almost twice the volume of baled or compacted peat moss. Fluffing (our scientific word) also allows you to have more equal volume measurements of the three ingredients as specified by Mel in his ALL NEW SQUARE FOOT GARDENING book.

It is important that all the ingredients be well mixed, again so it will be evenly moist and to make sure your compost, vermiculite and peat moss are distributed evenly. I also notice you mentioned wood compost products, if you go back to the home page, on the upper left you will see "hover" In the section there is a great write up on Mel's Mix How Strong is Your Backbone and how important it is to have a mix of at least five different types of good composts.

If you water in each layer of Mel's Mix as it goes into the SFG frame, you avoid having dry spots. If you put in a couple of inches of MM, then water well, by the time the box is filled, the peat in the lower layers has had a chance to fully hydrate and that allows it to soak up additional water easily. Don't let your MM dry out, ever. It becomes hard to rehydrate once it has dried out.

Edited again to add: Found Vale, OR on the far eastern side of OR at the ID border. Wow, much different climate from mine

vnoble wrote: I thought I had heard some say that organic matter (most of MM) holds more nutrients than mineral soils but this is not exactly true. Organic soils will eventually release minerals that are tied up in the organic matter or the microorganisms that are breaking it down but truth is a mineral soil has the potential for more available nutrients right now. It seems a little of it would be good for the plants in the short run. Other than nitrogen the mineral soil holds most nutrients until the plants need them. I have had many people that do container gardening that use a straight organic mix that they show up with a lot of nutrient deficiencies especially nitrogen.

Fascinating! Thanks for the info!!! I have noted others with similar results about N deficiency.Again, thanks for the info!
A lot of folks don't have the experience or the background knowledge that you have and I think the beauty of the SFG method is that it can bring pretty uncomplicated gardening to the uneducated masses.
I will be interested to hear how you take care of your watering issues. Do you have any photos?

Hi, vnoble,
Welcome.
Hot water soaks into peat moss much better than cold. I always pour boiling water on it to get it going.
Also gets rid of weeds, and boils your carrots in place. ;-)

j

vnoble, maybe you can help with this question...

I don't doubt your comment of releasing minerals as microbes break down topsoil. But, I think Mel may have mentioned (nobody quote me on this) that the difference with using soil vs compost is compost is 100% decomposable. Topsoil has inorganic matter in it that never fully breaks down even after it's nutritional value is used up.

Over the years, the inorganic portions of topsoil would build up and throw off the mix, yes? Only leaving behind stuff we couldn't use.

MM is already inorganic enough with the peat moss and vermiculite. That 1/3 we have left to supply nutrients needs something that is completely broken down in time.

I agree that topsoil has tremendous benefits. I believe that rivers flood farmlands to replenish nutrients and that there is no better way to revitalize soil. But, I don't know that we should have any more than 2/3 of our mix as inorganic matter. That's the only thing that concerns me with soils in our MM.

I will send pictures when I return to Vale. We have a 1500 sqft greenhouse that we raise poinsettias in the fall and bedding plants and hanging baskets in the spring in 2/3 of the house. The other third we had in bag/spayer hydroponics and the students individual hydroponics systems mainly raft and deep pot design. I decided that the square foot system would give them more decision making opportunity. It is also more likely that they will use the sqft method at home rather than the hydroponics methods.

Growing though the winter is a challenge as the days are short and we do not run the heat high for ideal growth. We got started late while we planned and built our boxes. I encouraged the students to select short season crops so we could get a harvest before christmas. The students got a good lesson on warm season crops and cool season crops as the cool season crops did well and the warm seson crops cucumbers and okra did not do much. They harvested raddishes, lettuce, and chard before Christmas and will harvest turnips and beets after. We will be replanting when we return in January.

We just sold our poinsettia crop in early December and will start our basket and bedding plant crops the end of January. We have run the green house for 24 years. In the beginning we mixed all of our soil which was a mix of 1/4 perlite, 1/4 vermiculite, and 1/2 peatmoss. The perlite adds air to the mix and vermiculite and peat are primarily water holding. Later on I decided that with our small cement mixer that too much time was spent mixing so we tried commercial premixed soil medias. We now use a Sunshine mix that is about 1/4 perlite and 3/4 peatmoss with a wetting agent added. The perlite (basically popped volcanic cinders) adds an air dimension to the soil and lets the water and air move into the media better. I have left over perlite from the hydroponics so I thought why not add some to MM to increase water and air intake. I was thinking the equivelant of say 1/5 of the mix.

Some of the students had trouble with damping off of seedings which would be lessoned by a little more air to the mix.

I would think that growing in the greenhouse compared to outdoors is an entirely different matter when it comes to soil mixes. Outdoors you plan to have your veggies/flowers growing there forever while in the greenhouse, its only short term. That's why we use specific seed starters and potting soils as opposed to compost and garden soil for the outdoor gardens.

I've always wanted a greenhouse. Would love to see yours.

Quiltbea,

We have our first frost in September and and our last frost in May or June so growing outside during the school year is not likely for us, while school is in session. If we start early and get things going before the days start getting too short we can get cucumbers producing by mid October and and Tomatoes by thanksgiving and then can grow on slowly till the end of January and then they take off, when the days get longer, until school is out the end of May. We usually keep things going with the hydroponics till mid July for the school staff and maintenance crews and then clean out the green and let it bake for a month and a half and then start all over again. This year will be different since the students will have their own crops so they may continue harvesting until the July clean out and bake time. The bake time kills bugs and diseases that may be in the greenhouse so we can start clean each fall.

Vnoble,

When you mention that soil holds various nutrients that leech out of " MM "or get consumed you appear to have missed the point that every time you take produce out of the beds you add a well balanced dose of five or more sources of composted animal manures and multi species/sources of composted waste vegetation .
The animal manures especially the horse muck can & in my mind should also contain hoof clippings, tail clippings and general hair that been brushed out the animal , The straw based poultry should also have feathers & the occasional broken rotted down egg in it.

When you add the extras like wood ash ,crushed eggshells , coffee grounds & things like fish waste ,dog/cat hair the quality rises , adding composted comfrey increases it even more but the final dose of combined compost given to the place in the box where the plant has been harvested does have to be well combined & evenly mixed before using it.

The use of dried worm castings aspect and having live worms in worm feeders in the beds munching on various fresh green waste obtained as domestic or industrial veg waste takes it even further .

Because you experienced problems of watering when no one was there could you not use small sections of buried drip hose running through beds , drippers or mini sprays at the water tap pressure triggered by battery operated timers twice or so per day like I did when I went away on seven weeks holiday .

Are there no crops such as root crops or things that need blanching you can sow , grow & grow a bit more under a thick blanket of straw that's put on the beds for frost protection.
Here in the UK up inScotland I believe it's quite a normal to bring things on that have been strawed & protected in this manner for several months and then harvest them as needed covering up after taking the crop to keep the ground from being frozen.
Your frost season is like much of the UK so instead of loads of salad criops we also use overwintering crops that can stand some heavy frost for a few days at a time such as kale , carrots , leeks ,cabbages . some times we construct poleyethen clotche type covers or use fleece blankets to hold off frost .

For the last three years in february /march time I have has temps as low as minus 18 centigrade for a run of three week or more and still had things I can eat out of the gardens because of using fleeces and putting them on in time.

My last plantings have been Japanese over wintering onions planted out at the middle of October & garlic cloves planted out four days ago . Broad beans would have also been planted but my family don't like them except me .
You can also plant overwintering peas here .

Thanks for the comments to help me think this through.

Microbes do not break down inorganic soil they work to break down organic ingredients. Inorganic soil ingredients sand, silt, and clay do not break down they remain and act to hold plant nutrients and either provide water storage (as with silt and clay) or aeration ( as with sand). That is why it is important to continually incorportate organic matter into the soil so there is a source of nutirents to be broken down to feed the plants or add fertilizer.

Mels mix is 1/3 inorganic as vermiculite, the compost and peat moss is organic. If we added a percentage of top soil it would not increase in percentage over the years because as the peat moss and compost break down, it is replaced with compost to keep the same level. The soil portion would remain the same because it does not break down and no more would be added. Regular soils value is that it stores minerals where organic soil of it self does not other than what is locked in it and it comes available as the compost continues to breakdown. Vermiculite being inorganic is just like regular soil other than water holding ability, it has no future mineral availability because as mineral soil, it is not organic and does nnot break down.

Peat moss is organic but breaks down so slowly that it supplies very little to the plants other than moisture holding and it is a poor holder of plant nutrients that become available from decomposing compost. Mineral soil especially silt and clay stores nutirents until plants need them with the exception of nitrogen which is free floating and does not attach to any soil particles.


When the rivers flood it does not usually add any nutrients. What it adds is more topsoil usually as silt that adds depth to the existing top soil which provides for more storage potential for nutrients that are made available from deteriating organic matter or added fertilizer. Mineral soil is not ever used up it is replenished by the addition of either fertilizers or the break down of organic matter by microorganisms. This is why we use green manure crops or plow down old plant material so that the soil is revitalized.

The mix of sand, silt, and clay is so different from place to place is why Mel came up with his mix. He wanted to have a consistant mix that was easy to work and everyone could count on. I have heavy clay soils in my area and they are a pain to work with since they are hard and cloddy. In my raised beds at home I added perlite and a lot of organic matter (manure, grass clippings, old cornsilage, composted shavings, etc) and it is better but not great. If I had a silty soil or loam soil they have low levels of clay and are easy to work. Mel did not swear off mineral soil because they have not value or get used up from what I have read in his book , he eliminated it because it was not consistant from place to place and his mix was. He was also trying to simplify gardening without having to give a long lesson on soils and their properties.

BackyardBirdGardner wrote:vnoble, maybe you can help with this question...

I don't doubt your comment of releasing minerals as microbes break down topsoil. But, I think Mel may have mentioned (nobody quote me on this) that the difference with using soil vs compost is compost is 100% decomposable. Topsoil has inorganic matter in it that never fully breaks down even after it's nutritional value is used up.

Over the years, the inorganic portions of topsoil would build up and throw off the mix, yes? Only leaving behind stuff we couldn't use.

MM is already inorganic enough with the peat moss and vermiculite. That 1/3 we have left to supply nutrients needs something that is completely broken down in time.

I agree that topsoil has tremendous benefits. I believe that rivers flood farmlands to replenish nutrients and that there is no better way to revitalize soil. But, I don't know that we should have any more than 2/3 of our mix as inorganic matter. That's the only thing that concerns me with soils in our MM.

Surely vermiculite in the mix does act as a reservior for the liquified nutrients that form out of the decaying compsted manures and vegetation matter. That is doing the same job as the clays except the vermiculite actually allows for better access by the plant root hairs to drink the nutrients due to the fact that when clays dry out they lock in the nutrients .

It's a well known fact most clays contain everything for plants to grow they just don't like releasing it when the plants want it hence the tilling, manuring and adding compsts by farmers & gardeners over the centuries to get the clays in small enough particles ( ading lime ) and wet enough to make their reserviours of moisture & nutrients available when the plants need it.

Ordinary soil does indeed break down into several components as well as the sand breaking down from pepbbles , grains & dust sized particles go to any tidal river estaury and you'll find gloopy mud in all sorts of stages of break down .. add a few million years , have a crush on it , it compacts and becomes a form of slate.

You say river flooding does not bring nutrients with it , I'd say otherwise.
Haul up a couple of buckets of flood water , filter it out and see what is in the filter , it certainly is'nt Scotch mist .
Look at it under a microscope and besides all sorts of dead or alive animal life there is loads of decayed & decaying vegetable matter .

Also think about once the flood subsides , whats left .... usually some stinking slimy mud containing very little coarse grit , having loads of rearranged vegetation in it and dying rooted in the flood plain plants that the flood waters& mud covered .

Surely that's why you get the stinking mud which becomes an excellent fertiliser with decaying matter in it ?

I'm not going to nit-pick with you, vnoble. I truly appreciate the detailed answer to my question.

One concern with clay, though, is compaction. So, we obviously would need to watch our levels of clay as a percentage of the mix.

I think you said it best yourself, though. Mel wanted to keep things simple and consistent from place to place and provide an easy medium people could count on. So, I guess I go back to.....why change it? We know it works.

Tinkering with soil composition is natural for a lot of our personalities. I don't personally have a problem with it if someone knows enough of what they are doing. However, while posting on the forum, I firmly stand by Mel's techniques because they work (first and foremost) and most people here are new enough they wouldn't know what to tweak and would just make themselves a mess of an imbalanced garden, then proceed to come here and blame the forum, and it's members, for their mistakes.

I would love to chat with you because I'm sure you can teach me a ton about the details of soils, etc. However, if it's not 99% in line with Mel's book, we might want to chat about changes/tweaks in the Non-SFG subforum since we are deliberately going "against the grain" a bit.

Sorry, but you guys are getting to darn technical for this old broad. Geniuses! Please move to the back of the room.

quiltbea wrote:Sorry, but you guys are getting to darn technical for this old broad. Geniuses! Please move to the back of the room.

I think you mean "move to the front." Either way, I definitely need to sit with the majority of the bell curve.