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 MittleiderGardeningGroup@yahoogroups.com, 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.

Which material is best for building Grow-Boxes? And what about gravel in the aisles?

Q. I was telling my husband I needed 8″ Redwood or Cedar for the grow boxes and he asked if it wouldn’t be better to use “Trex” as that doesn’t seem to ever wear out.  Is there a reason to NOT use Trex?  (web site about Trex https://www.trex.com/)  Is there an advantage with Redwood/Cedar that is not there with Trex?

Also, we are getting dirt to put under the boxes and level the area.  They tell me it would be much less expensive to get crusher tailings (rather than topsoil).  Would this be just as fine since I’m putting grow boxes on top or should I get top soil since the roots may go down into the dirt?

A.  Redwood and cedar are good for Grow-Boxes because they last a long time, and do not deteriorate like pine.  However, they are expensive, and it costs much less to use pine and paint it, or even to use treated lumber.  Trex looks great, and will last indefinitely, but I suspect it is very expensive.  We encourage people to do things without incurring any more expense than necessary, so I probably wouldn’t recommend Trex for that reason.

Anything you put down on your soil will be there a LONG TIME.  Unless you want to deal with crusher tailings forever, I wouldn’t put them there.  Paying for topsoil isn’t necessary, however.  I would get any clean fill-dirt that’s available.  On the same subject, sometimes folks want to put gravel or wood chips in the aisles.  Unless you get a lot of rain and your aisles would be muddy most of the time, I recommend you leave them alone.  Just do the nominal amount of weeding it requires to keep them clean, and with no watering, they remain dry, clean, and pleasant.  Gravel, wood chips, etc., can be a real pain to push tillers, wheelbarrows, etc. through, and even walking isn’t as nice as on clean, hard, dry dirt.

Materials to use for Grow-Boxes – Or Why Not Grow Right In The Dirt??

Q.  We are starting a container, or Grow-Box project at an orphanage in northern Mexico. We are having a hard time finding saw dust or peat moss. There is soil conditioner available at a nursery for $3 a cubic ft. Is this a feasable alternative to mix with the sand?   Thanks. Dr. Don
A.  May I inquire first as to why you are not growing right in the regular soil?  If you’ve been told “nothing will grow there”, or “the soil’s worn out,” don’t believe it!  “SOIL IS SOIL”, as Dr. Mittleider often says, and what he is trying to convey is that you can grow great gardens in virtually any soil, anywhere in the world!!  Therefore, unless there has been a garden in that spot recently which was diseased, I would suggest you just make level, raised, ridged soil-beds and grow “right in the dirt”. 
The Mittleider gardening book Grow-Bed Gardens actually has pictures of great soil-bed gardens in Mexico, as well as many other places throughout the world.  It’s available as part of the Mittleider Gardening Library CD at www.growfood.com.
By using the balanced natural mineral nutrient fertilizers we recommend, your crops will thrive in any soil that is not toxic or diseased. The formulas are on the website, in the Learn section on the Fertilizer pages, and you can get them already mixed in the Material section of the Store – also at www.growfood.com.
If for some reason you really must use Grow-Boxes, because you have no ground, but only a driveway, patio, or rocks, then go for it.  But DO NOT USE dirt in the Grow-Boxes! 
And I DO NOT RECOMMEND soil conditioner as a viable alternative to sawdust and sand in your Grow-Boxes – especially at $3 per cubic foot.  There are three reasons I think of at the moment:
1) the cost amounts to about $90 per 30′ Grow-Box.  We are all about making gardening affordable to those who have very little money, and this flies in the face of that philosophy. 
2)  Usually, soil conditioners have small amounts of a few of the nutrients in them, but you rarely know what is there, and it is never just what is needed.  So it can actually do more harm than good if it creates an excess of any nutrient. 
3)  Unless you KNOW the source of the materials used in the soil conditioner – that they are all clean and free of diseases, bugs, and weed seeds – you run the risk of introducing problems from those sources into your garden.
I DO RECOMMEND you look for other clean finely ground-up organic materials that are available free locally, or at very low cost.  A few suggestions include 
1) coffee hulls,
2) rice hulls,
3) finely chopped coconut husks,
4) sugar cane refuse (Bagass, or the result after pressing the sugar from the canes),
5) leaves (but avoid scrub oak below 5,000 feet elevation and black walnuts), and
6) a really good option is pine needles (yes, these work great, and will not ruin your garden!). 
If you can find a hammer mill to chop the materials finely, any of the above will work well for you.  Have success, and don’t hesitate to ask questions!

Wood For Grow-Boxes

Q.  I am a bit confused about what type of wood to use for my grow boxes. I was told by some one that I should coat the inside of my grow box with Asphalt Emulsion to keep the moisture from getting into the wood. Is this true?

A.  Check to be sure there is no creosote, or other harmful material in anything used for painting the inside of your Grow-Boxes.  Painting both inside and outside will help preserve the boxes, and I have seen boxes in continuous use for 25 years in Dr. Mittleider’s own garden.

If using treated lumber, make certain it does not contain harmful substances as well.  Most people use pine or other inexpensive lumber, and then paint it.

Bricks and cinder blocks, as well as other materials, have also been used successfully.  It is best to use mortor, to give the walls strength, if bricks or blocks are used.

The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased as digital downloads.  I HIGHLY recommend that you look here https://www.hightechhomestead.com/Products.htm for the best gardening books available anywhere!  They are available INSTANTLY, as well, with no time or cost for shipping.  Do it now.

Containers – Depth, Width, Materials & Drainage

Q. I’m building a large Grow-Box 3′ high 3′ wide 15′ long. We receive 10-12″ of rain per year; we have mostly clay soil. 1) I’d like to promote better drainage and have a 3″ soil augur. Is it better to fill my holes with a gypsum and soil conditioner mix or a gravel and gypsum? 2) I’m hoping to get some County compost to mix with sawdust, sand, gypsum and clay to fill the mankiller in disguise.

A.   A real drainage problem is almost unheard of when using containers, and especially in the dry country you describe.  If you must dig, fill auger holes with course gravel. More likely, you would want to preserve every drop of water for the plants, rather than expediting the drainage. For example, even without raised containers, by making level, raised, ridged beds right in the soil, and having the planting area an inch or so above the aisles, you will normally solve any drainage problem in the low rainfall area in which you live.

Why is your Grow-Box 3 feet deep? If bending over is a problem, I recommend 18″ or at most 2’.  If you like working in a Grow-Box rather than the soil, and low bending isn’t a problem, consider building it 8″ deep.  And for any depth box, fill with peat moss, sawdust, perlite, and sand, in equal amounts by volume.  Any combination is fine, so long as the sand is 25-35% maximum. 

Also, build it 4′ wide, rather than 3′, if you have the space. This size will give you 4 rows of most vegetables, while still allowing plants the light they need, while a 3′-wide box only gives you 2 rows.  Excellent detailed instructions for building Grow-Boxes are in most of the Mittleider gardening books, available at www.growfood.com.

You speak of gypsum as if it was a major ingredient in your soil mix.  In a Grow-Box 8″ deep X 4′ wide X 15′ long, apply just 2# of gypsum evenly over the surface of the soil under the Box before you fill with the planting mix. Then, after filling with the planting mix, apply another 2# evenly over the surface and work it into the soil mix.   After each crop apply 2# to the soil mix and work it in.

Perhaps you only meant to use the gypsum in the holes you propose drilling into the clay soil beneath the Grow-Box.  If that’s the case, I would use sand and gravel in the holes.

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://www.hightechhomestead.com/Products.htm for the best gardening books available anywhere!  Get one NOW and be gardening TODAY!!

Growing Commercially – Mittleider VS Hydroponics

Q.  We want to go into gardening commercially, and hydroponic greenhouse growing has been recommended.  How is your Method similar or better for us than going hydroponic?

A.  Before you spend any money on Hydroponic buildings and equipment you need to learn about the Mittleider Method, for sure! Building a Mittleider-style greenhouse will save you many thousands of dollars in the building of it and many thousands more in operating costs.  The Mittleider Method is sometimes referred to as modified hydroponics, because we feed the plants the 13 necessary nutrients, in a scientifically balanced ratio.  However, rather than putting expensive instantly water-soluble formulas in the water supply, we use Natural Mineral Nutrients that are easily and inexpensively obtained and apply the nutrients right on the soil – then water them in.  Also, as alluded to in the previous paragraph, unlike hydroponics, we grow plants right in the ground, or if we’re in Greenhouses we use raised Grow-Boxes with open bottoms, so the plants still have access to the natural soil – to obtain other nutrients they may want or need.  Mittleider gardens are well known for producing tremendous yields, even approaching those of hydroponics, while our crops like tomatoes are better tasting and cost a small fraction of those grown by hydroponic methods.