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
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
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!

Replacing Soil-less Growing Medium

Q.  When I told someone I was growing in a sand+sawdust mix, he said that the sawdust will decompose with time, leaving me with only sand.  I recall reading on your website that the planting mediums do not require to be replaced.  What is your experience with this?

A.  Organic materials will, indeed, decompose over time.  They do not disapear altogether, but you will need to supplement them occasionally.  Sawdust is slower to decompose, and thus is useful for a longer time than peatmoss.  And perlite – if you can get it inexpensively – lasts a very long time.  Coconut husks also hold up well, but rice hulls decompose rather fast.

Dr. Mittleider has had the same Grow-Boxes in his backyard garden for over 25 years, and never totally replaced the materials, to my knowledge. He has supplemented regularly, however.

When we say the materials don’t need to be replaced, we mean that so long as there is no disease present, you can continue to use them – supplementing as necessary to keep the box full of soil mix.

Also, in a tropical country, organic materials will decompose faster than they do in colder climates, because not much decomposition happens when materials are frozen during the 4-6 months of winter.

How to Grow the Healthiest Vegetables

Q.  I want to grow the healthiest vegetables possible. Isn’t organic gardening healthier than the Mittleider Method – tell me the truth!

A.  This is a very good question and it deserves a straight answer. I will therefore tell you some very important things about plant nutrition. First of all, plants receive nutrition only as water- soluble mineral compounds, through their roots. When we put compost or manure, etc. into the soil, the organic material must first decompose, and the nutrient compounds must revert to water-soluble minerals before the next generation of plants can use them. This takes time, and sometimes as much as half of the nutrients are lost in the process.

Secondly, there is no difference between organic, mineral, and chemical nutrients.  Everything in this world is a chemical!!  To the chemist everything in the soil is called chemicals, to a geologist they are called minerals, and to an organic enthusiast they are called organics, but they are the same substances.  To quote J. I. Rodale, “we organic gardeners have let our enthusiasm run away with us. We have said that the nitrogen which is in organic matter is different (and thus somehow better) from nitrogen in a commercial fertilizer. But this is not so.” And “actually there is no difference between the nitrogen in a chemical fertilizer and the nitrogen in a leaf.” (Organic Gardening)

Thirdly, there is no difference between soil and rocks except for the size of the particles, and 12 of the 13 mineral nutrients plants require are essentially ground-up rocks! There is really nothing “synthetic” about them.  So, you see there is no difference between “organic nitrogen”, mineral nitrogen and chemical nitrogen – except the nitrogen that is part of an organic substance must decompose and revert to the water-soluble mineral state before being available to plants.

This being the case, what should we do to assure we have the best garden and the healthiest plants possible? Give the plants the best combination of nutrition we possibly can.  Remember that 99% of us depend on 1% to feed us, and the big growers feed their crops! The big fertilizer companies use formulas similar to Dr. Mittleider’s and call them “The preferred horticultural mix.” Just check out Scott’s Peter’s Professional Pete Lite as an example.

Now, this is not to say that organic materials don’t have a place in the garden. You can improve soil texture and tilth by adding materials that have desirable characteristics.  However, improving the soil in that way is not necessary to having a good garden, and people often introduce weeds, rodents, bugs, and diseases into their gardens, or provide a haven for them with their organic mulching practices. It is for this reason that we do not emphasize and encourage composting and manure. 

Mittleider gardens qualify as “organic” because we don’t use pesticides or herbicides.  However, I suggest they are even “better than organic”, because the plants receive just what they need, they grow fast, and we almost never have insect or disease problems because they aren’t in the ground long enough for the pests to get established.