Soil Medium to Use for Grow-Boxes – Or How About Growing in the Ground!

Q.  In Trinidad, bagasse was the popular choice as a medium. The sugar industry is now closed and bagasse is no longer available. Is there a suggestion? There is no other crop by-product that can be obtained cheaply.  Simon Bedasie, Agronomist

(Trinidad and Tobago have over 200 commercial growers using Mittleider’s methods in boxes, using bagasse (sugar cane stalks) as their growing medium.  Now that the sugar industry has closed down, I wonder how they will cope.)

A.  Do you have access to coconut coir – which is ground-up coconut husks?  How about coffee or rice hulls?  Peanut shells?  You probably don’t have pine trees, do you.  Ground-up pine needles are good also.  Is there no wood industry there, where you could find sawdust? 
If you can find NOTHING in which to grow, I suggest you try growing right in the native soil.  We do that in most places around the world now, and have success everywhere.
Create a level soil-bed.  When growing commercially things like lettuce and other small crops the bed is 4′ wide, and whatever length you want.  Make at least 3′-wide aisles, and pull dirt from those aisles to make the beds a couple of inches higher  than the aisles.  Make ridges all around the beds at least 4″ high, to hold water.
Feeding, watering, and growing are the same as in the raised boxes, but you will have weeding to do.
Look on the website at in the Learn section to see how to grow in the dirt with the same success you have enjoyed in raised boxes for so many years.
Jim Kennard

Are Sawdust, Sand, etc. Used in Regular Mittleider Gardens – or Only in Grow-Boxes – and Why?

Q.  I have seen many pictures of both soil boxes and beds.  I read where
the soil in the boxes is basically a soiless mix, but the beds I see look as though they are made with the soil pulled up and ridged.  There is no difference that I can see between the beds and the paths in many pictues.  The soil color and texture is the same in both the paths and the ridged beds in many of the pictures, leading me to believe there was only soil used in their construction, unless of course the entire garden was amended, which seemed unlikely to me.

A.  You’re right. When we garden in the dirt we use whatever dirt is there.
And we promise people “a great garden in any soil” with no soil amendments.
That is no idle promise either, as we never amend the soil in any of the
projects we work on, unless it’s to till into the soil the clean plant residue
of the preceding crop.  The reason we can promise – and deliver – a great garden in any soil, is that the Mittleider Magic natural mineral nutrients provide the nutrition the plants need.  Perhaps that’s why some people call them “the poor man’s hydroponic mix.”

Growing in containers, on the other hand, is a different proposition, and we
recommend no soil be used.  There are several advantages to container gardening, among them avoiding any problems with weeds, diseases, and bugs, all of which often reside in the dirt found in our gardens.

Dirt is also MUCH heavier than sawdust, peat moss, perlite, rice hulls, pine
needles, etc., and over time pushes the container walls out.

Recommended container “soil” mixtures also perform the 5 essential soil
functions better than most dirt, without some of the negatives, such as clay
soil’s tendency to bake hard, crack, not drain well, and not allow roots to
penetrate easily. For example, it warms up better in the spring, yet it stays
cool in the summer; it holds moisture well, yet never stays wet enough to drown the plants and provides ample soil air; it anchors plant roots well, but they are easy to pull when necessary; it holds the fertilizers, and yet they don’t
become “fixed” or adhere to the soil particles as much as they do in the dirt.

And of course the lightweight materials are great for growing and harvesting
root crops.

With all these advantages, why don’t we promote Grow-Box gardening more?

Thirty years ago Jacob Mittleider promoted it heavily, because he felt that for a
serious gardener the advantages outweighed the disadvantages.  But over time he came to realize that the following negatives – for most people – outweighed the positives.

There are significant cost and time elements in building and filling containers.
Also, they are less forgiving for such things as neglecting to water or feed
regularly.  And in some locations the cost is truly prohibitive, materials just
aren’t available, or would be destroyed quickly by insect pests.

So, if you lack soil in a sunny spot, build a Grow-Box.  Or if you are infested with bugs, weeds, or diseases, build Grow-Boxes.  They really are a wonderful way to grow huge crops of healthy vegetables.  But for most of you – who have dirt to use and don’t want the expense and time commitment required to build containers – grow in the dirt with confidence that you really can have a great garden in any soil, and in almost any climate!

The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads. 

A digital copy costs 30-40% less, and is available instantly!  I HIGHLY recommend you look here for the best gardening books available anywhere!  Get one NOW and be gardening TODAY!!

Sawdust/Sand Mix – Problems with Termites or Wind?

Q.  Doesn’t using sawdust attract termites? Is sawdust the only planting medium that goes in the boxes? How do you keep it from blowing away?

A. Termites seem to like wood that has not already been chewed, as we have never had a problem with them taking up residence in the Grow-Box materials. On the other hand, if you don’t protect your wood frame by treating or painting, you may see some termite or other activity.

Four things prevent the sawdust from being blown away by the wind: 1) The walls of the Grow-Box on all sides protect it. 2) It is mixed with sand – with at
least 25% by volume being sand. 3) Daily watering keeps the mixture moist, and heavy enough that it won’t blow away. 4) Plant roots, stems, and leaves hold the material in place and protect against wind action.

Containers on Concrete – Depth of Soil Needed

Q.  I am constructing some 18″ wide Grow-Boxes.  I have run out of dirt area, but have a slab of concrete on which I’m putting 3 boxes.  My question is: If I am going to grow kale,chard, spinach, and greens, how deep does the soil really need to be in the boxes?  Will 4 to 5″ be enough?  Or do I need to fill the box to the top?  For carrots, I’m assuming I’d need to fill it to the top. 

Also, My bell pepper plants survived the summer and are producing again, but the peppers are small.  There are a lot of them on each plant, so should I prune them some?

A.  Do not skimp on the soil mix in your Grow-Boxes.  All root crops obviously need the full 8″, just so the roots can grow to full length, but other plants also need space for their root systems.  You need the 8″ depth for several reasons, including:

1) sufficient room for roots to grow properly,

2)  enough soil mixture to hold sufficient water for the plants,

3)  enough soil mixture to keep from heating up too fast in the hot weather,

4)  matching amounts of fertilizers to soil mixture, so you don’t end up with salinity.

Each of these are important.

Don’t prune the peppers unless you have close to freezing temperatures and you know they won’t mature.

The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads. 

A digital copy costs 30-40% less, and is available instantly!  I HIGHLY recommend you look here for the best gardening books available anywhere!  Get one NOW and be gardening TODAY!!

Small Containers – Figuring Nutrients

Q.  I live on a very small city plot and have almost no spots that get
southern exposure enough that veggies will grow. I have a couple of

1. I would like to put a grow-box in a 20″x90″ site for tomatoes.
This spot is between the house and the sidewalk. Will this work? How
do I figure for nutrients, watering, etc.?

2. The only other place I have is also small; however, it is a cement
slab. Will a grow-box work over cement? Would I have to increase the
heighth of the box to help accommodate for the lack of ground soil?

A.  What you have is a 7 1/2′-long Grow-Bed or box – you can grow in the dirt, or in a container.  It will certainly work, if you have full sunshine for 8+ hours.   You can grow 11 tomato plants in that space – enough to produce about 200# of fresh vine-ripened tomatoes!  Who said you can’t grow a garden in a small space!

If you’re going to grow in the dirt, just dig it thoroughly, eliminating all weeds.  While digging add 8 ounces of Pre-Plant Mix and 4 ounces of Weekly Feed Mix, and mix thoroughly with the soil.

Make 4″-high ridges around the edges by pulling soil from the center of the bed. You should end up with an actual planting area about 12″-wide and 7′ long.

Each time you feed, you should use 4 ounces of Weekly Feed Mix.  Watering should be every day, because the location will be very hot, with the house on one side and a sidewalk on the other.  In the heat of summer you may need to water a second time.  Apply enough water to leave 1″ of water standing in the bed.  If that doesn’t soak in within a couple of hours, then put less in until it does soak in within 2 hours maximum.

You can also build a Grow-Box on your cement slab.  Thousands of MM gardeners have grown this way, with no more height than 8″.  Watering daily is critical, because the sawdust/sand mixture won’t hold water the same way clay soil does.

Fertilize an 18″-wide bed or box with 1 ounce per foot of Pre-Plant Mix – one
time.  Weekly Feed should be applied at the rate of 1/2 ounce per foot of bed or box.

Most things you plant will be on both sides of the bed or box, so you are
actually feeding two rows of plants with that feeding regimen, unless it’s
tomatoes, cucumbers, or other climbing plants, which are only planted one row per 18″-wide bed or box.

Having Trouble Finding Good Soil Products

Q.  since the goal is to use inexpensive materials, and also the right mix of ingredients, I am now at a stopping point.  Other than very pricy small bags of peat I cannot find organic media as recommended in the Gardening Library.  What should I do?

I can get topsoil in bulk, but which is preferred?  Mushroom Mix or some other type?

I estimate I will need 10-15 cubic yards. I will be container gardening in 100 – 5 gallon buckets.  No way to build grow boxes because I live in a rental that has low maintenance rock garden and desert shrubs.

A.  If you just need enough for 100 – 5-gallon containers, you should only need 2 1/2 cubic yards of material.  One cubic foot = 7.5 gallons, so 500 gallons = 67 cubic feet,  and 67 cubic feet (67/27) = 2.48 cubic yards.

I recommend you stay away from topsoil, or any other type of dirt, for that matter.  In buckets, or other containers, dirt will set up and become very hard.  It’s also very heavy, and disagreeable to work with. 

I take it there are no lumber mills nearby.  What about forests or stands of pine trees?  Pine needles would be excellent.  Are there any stands of cedar trees in your hills?  the “copi soil” beneath those, which consists of previous years’ dropped needles, would be good also.

The lighter the material the better, so long as it is clean and weed-free.
In Utah, mushroom mix has no dirt in it, but is organic material made from shavings, sawdust, turkey droppings, etc., and therefore it could be very good.

Growing in 5-gallon containers in the heat of the Southern Nevada desert will be a real challenge.  I hope they are at least white, to reflect a little sun.  Your biggest challenge will be to keep them moist and cool.  Anything you can do to keep the sun off the containers will be helpful, and watering multiple times each day will likely be necessary.

If that is all you need, perhaps you can find some help with peat moss,
perlite, etc. and not end up with dirt in your containers, which will be

Additional information on container gardening can be found in Gardening by the Foot and the Mittleider Gardening Course, available at

The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads. 

A digital copy costs 30-40% less, and is available instantly!  I HIGHLY recommend you look here for the best gardening books available anywhere!  Get one NOW and be gardening TODAY!!

Growing in Pots – How Much Fertilizer to Use

Some of you who grow in containers may want to grow in pots of different sizes, and will need to know how much Pre-Plant and Weekly Feed natural mineral nutrients to use. 
Starting from the basics:  Dr. Mittleider tells us to mix 1 1/2 ounce (3 tablespoons, or 9 teaspoons) of Pre-Plant into the soil of an 18″ X 18″ X 2 3/4″ square flat, and 1/2 that amount of Weekly Feed.  All of this before planting seed or seedlings.  Let’s do the math and see how much soil we have, then we can translate it into other size containers.  18 X 18 X 2.75 = 891 cubic inches.  With 1728 cubic inches in 1 cubic foot, we have .5156 cubic feet of material in an 18″ square flat.  We will round to 1/2 cubic foot.
Suppose you have a 6″ round pot that’s 6″ deep, and want to know how much to use.  Multiply pi X radius squared X height, or 3.14156 X 9 X 6 = 169.64.  Divide by 1728, and you have .098, or 1/10th of a cubic foot.
Since you will apply 9 teaspoons of Pre-Plant to 1/2 cubic foot of material, you would apply 2 scant teaspoons to the soil in your 6″ pot.  Plus, you apply 1 scant teaspoon of Weekly Feed.
For on-going feeding of the plants in your pot, you either water with the Constant Feed solution of 1 ounce (2 tablespoons) in 3 gallons of water, or you can sprinkle 1 scant teaspoon of WF on the surface and water it in.
Now suppose your pot is 6″ square, instead of round.  Multiply 6 X 6 X 6 = 216 cu in.  Divide by 1728 = .125, or 1/8th of a cubic foot.  Nine is to .5 as X (the unknown) is to .125 = 2.25.  So you apply 2 1/4 teaspoons of Pre-Plant and 1 1/8 teaspoons of Weekly Feed to a 6″ square pot of soil mix.  Did everyone follow that?  Probably not, but if you will follow those simple formulas you can know how much PP and WF fertilizers to apply to any size container you might be using.
Isn’t it nice to know what you’re doing, and be able to eliminate some of the unknowns in the gardening equation?  For an excellent book on growing in containers get Gardening By The Foot (NOT Square Foot Gardening) by Jacob Mittleider, available at

P.S. The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads. 

A digital copy costs 30-40% less, and is available instantly!  I HIGHLY recommend you look here https:// for the best gardening books available anywhere!  Get one NOW and be gardening TODAY

Build Grow-Boxes From Old Tires – They Last “Forever” and They’re Free

Group:  Joe – kindly shared with us his experience making Grow-Boxes out of old tires.  I believe this has merit, and perhaps some of you who want to use Grow-Boxes will want to save this set of instructions against the time you need it.  It’s just another way of doing container gardening. Thanks Joe!
“Hope this will help someone.  In our area we had hurricanes this past year, and lumber is terribly expensive, so we just had to have an alternative.  The tires are not my original idea.  You can learn more at the Robert Noble Foundation website  And some good pictures – also from the same website, are
Here’s how to make Grow-Boxes using old tires.
1) Get some free 15″ tires that are all same size.
2) Cut the sidewalls off with a sharp knife or jigsaw. 
3) Cut all the way across tire with a hacksaw. 
4) Lay tire over work area thread side up.
5) Take another tire and slide 6″ under end of first tire. 
6) Screw sheet metal screws into the 6″ overlap, 1″ in from each corner.
7) Continue on till you have the length tire board you want (over 30′ does not stretch correctly). 
8) Leave enough on each end to fold back over tire (make a tight fold back but leave space to slide in a piece of 5/8″ rebar).
9) From another tire thread cut some 6″ wide pieces.
10) Starting from fold back on the tire board, measure and mark at 18″ intervals,  all the way to the other end.
11) On thread side at these marks center and screw the 6″ pieces with sheet metal screws, 1″ in from each side and centered from top to bottom. 
12) Stretch a tight string 1′ high and length of box – plus 2′ more on each end .
13) Drive 1 piece of 5/8″ X 36″ rebar into ground at starting point of grow box. 
14) slide board end loop over post, being sure that thread, with patches face out.  Later it will be easy to replace if necessary. 
15) Push 2 pieces of rebar into ground at 3′ intervals and 1″ outside string.  Slanting the rebar away from string thus creating a wedge to hold tire on edge.
16) At loose end of board slide the 10″ piece of rebar through loop.
17) Straight in line with string, put temporary post in ground inclined away from the box and 6 to 7 feet from the end of the Grow-Box.
18) Make sling to go around ends of 10″ rebar. 
19) Connect one end of come-a-long through loop you just created. 
20) Attach other end of come-a-long to incline post  that is 6-7 feet away but in line with where end of stretched tire board will be. 
22) Drive one 18″ piece of rebar down between each of the outside 6″ tire pieces and tire board thus anchoring the grow box side every 18″. 
23) When you reach the end remove come-a-long and the piece of 10″ rebar. 
24) Slip corner post through loop and drive rebar into ground. 
25) Make other side of grow box the same way.  
26) Cut one more tire. Use as is (after cutting to fit) and loop from inside end of one tire board to the inside end of the other tire board.
Parts; Sheet metal screws – tires – Rebar – 3/8″ X 18″ Stakes for every 18 inches,  5/8 X 36″ – 4 corner posts, 5/8 X 10 – 1 for stretching tire board – String and stakes to stretch line where box side will be.
Happy gardening. Joe

4′-Wide Grow-Boxes – How Many Rows of Climbing Plants to Grow

Q.  Since we can grow 4 rows of plants in a 4′-wide Grow-Box, shouldn’t we also grow 4 rows of beans, tomatoes, and other climbing plants?  That way we could just run each row of plants up a set of strings to one side of the T-Frame.
A.  You should have only two rows of any of the vining or climbing plants in a 4″-wide Grow-Box.  They are planted 10″ to 12″ in from the outside edge of the box.  Pole beans should be planted 1 1/2″ to 2″ apart in those two rows.  Tomatoes  are 9″, cucumbers may be anywhere from 6″ to 8″, depending on variety, and eggplant and peppers are 7″ apart. 
T-Frames are installed on the inside edges of the Grow-Box, no more than 10′ apart.  Galvanized pipe (1/2″ preferred) or #8 wire is placed 1″ from the ends of the T to give you 4 rows of plants as they climb up the strings.  Every other plant should be trained to go up strings to opposite sides of the T.
If you were to plant 4 rows instead of 2, you would make the care and feeding of your plants very difficult, so just plant a single row of plants for each set of T-Frames, but plant them half as far apart.  Then separate them as they grow up the strings.  They will get plenty of light from the separation, and plenty of food and water, because the roots will spread throughout the entire box.  And you will have an easy time weeding, feeding, watering, and harvesting your plants, because the bed is open and available to you.
Excellent pictures are in Gardening By The Foot, and illustrations are in the Mittleider Gardening Course, both available at


The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads. 

A digital copy costs 30-40% less, and is available instantly!  I HIGHLY recommend you look here for the best gardening books available anywhere!  Get one NOW and be gardening TODAY!!

T-Frames in 4′-Wide Grow-Boxes

Q(s).  I have questions on building the T frames.   I read in one of your earlier posts that when you have a 4′ x 30′ box you place the 4×4 posts on the inside of the box but at the outside edges.  Is that correct?
1. So I would use 8 posts ( four on each side) on each bed?
2. Why have 16″ or half of the T hanging over my grow box into the 3.5′ isle?
3. Why not just use 4 posts placed in the center of the two foot-wide bare spot in the middle of the four foot bed.  The end of the T”s would be 16″ narrower than the bed or 8″ short from the edge on each side.  Would it hurt to have the plants climbing up on an angle from the outside of the box towards the center 8″?

4. I may try the PVC frame over the T-frames to make a greenhouse, in order to extend the growing season.  Is that a good idea?

If I try enclosing the bed is this the reason for placing the T posts on the edges of the box?  Then would I walk down the 2′ isle in the middle of the 4′ bed?

5. How much Pre-Plant Mix do I spread on the inside of the grow-box before I fill it with my mixture of sawdust & sand?  The Gardening Course says 2 lbs. For a 18″ X 30′ bed.  Do I double that and put 4 lbs. Down and not put any gypsum down in the center of the box?  The Grow Box Garden book said 10 pounds of gypsum for a 5′ X 30′ box?


1.  Yes, if you are using a 4′-wide box, one big reason for doing so is to maximize your yield in a given space.  You can put two rows of climbing plants in a 4′ bed, which produces as much in 7.5′ width as an 18″ box or bed grows in 10′ of width.  But you should expect to be diligent in your pruning!
2.  The T hangs out into the aisle only 12″ or 13″.  This maximizes the sun-exposure for your plants and uses the space most efficiently.
3.  Have you ever seen poles placed like an indian tepee, with plants placed around the outside, and trained to climb the tepee?  That’s a similar idea, and it is just the opposite of what you want.  As the plants grow taller and bigger they need more light, but because they are growing toward each other and getting closer and closer together, they get less and less light, thus greatly reducing your yield.  If you place your T-Frames in the middle of the Grow-Box, in order for them to get adequate light, you can only grow 1/2 as many plants in the same space.
4.  A PVC frame over the top, such as the one shown in the picture in the Photos section of the, is a very good idea.  You can then use your Grow-Box as a greenhouse in the spring, and it will extend your harvest by several weeks in the fall.  I recommend you take the plastic off, however, in the summer, as it provides some shade, and you want maximum sun (unless you are in the tropics and the temperatures are over 100 degrees fahrenheit).
If you are using the Grow-Box as a greenhouse in the early spring, you may want to keep it tightly enclosed and walk down the center, but you should ONLY do it after placing 2″ X 12″ boards the length of the box and supported, so you don’t compress the soil mix.  After your plants are growing, and especially when they have begun to mature, you should not walk down the center of your Grow-Box.  And there will be no room for you to do so, even if you wanted to. 
In building the frame and covering it with plastic, you should nail 1″ X 2″ boards to both sides of the plastic at the bottom, on the sides of the Grow-Box.  String ropes under 4 points along the side, and tie loops in the ropes.  Then raise the sides by hooking the loops to a stratgeically-placed nail for maximum light on warm days, and so that you can get into the box to feed and harvest.
5.  Since Grow-Box Gardens was written 30 years ago, Dr. Mittleider has determined that 5# of Pre-Plant mix is adequate to be placed on the dirt under a 5′ X 30′ box.  For your 4′-wide box spread 4# of Pre-Plant Mix evenly on the soil under the box.  Of course you will also mix 4# of Pre-Plant,along with 2# of Weekly Feed into the soil mixture as you are filling the box.