Growing Strawberries in Grow-Boxes

Q.  How do strawberries do in the 18″ sawdust rows?  And how is the fertilizer regulated? 

A.  Growing strawberries in the Grow-Boxes can be very rewarding and successful.  With no weeds to compete with them, and make it difficult for you as the grower, they do very well.

As the runners leave the box and begin to root in the ground surrounding the box you need to cut them off, or they will very soon be in your aisles.

Fertilizing depends on the variety you are growing.  If you are growing a single-crop variety you will only need to fertilize 3 or 4 times the first year, and 3 times after that.

ever-bearing, or two-crop varieties will need more feeding.  Just remember that you don’t feed after the blossoms appear, unless it is a true ever-bearing crop that just “keeps on giving”, and then you stop 8 weeks before the first frost.

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!!

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

Using Dirt in Grow-Boxes – or Growing Right In the Dirt

To further clarify my last post, most of the time we grow right in the existing dirt, with no soil amendments – no matter how “worn out” or “bad” it is.  Whether you have heavy clay or straight sand, or enything in between, unless the soil is diseased, toxic, or under water you can grow a great garden right in the soil.

However, “If for some reason you really must use Grow-Boxes, because you have no ground, but only a driveway, patio, or rocks, (or if you just want the many benefits offered by Grow-Boxes) then go for it. But DO NOT USE dirt in the Grow-Boxes!”  Following are a few of the many reasons not to use dirt in Grow-Boxes.  I recommend you save this information if you are contemplating that method of growing.

Grow-Boxes are designed to give you an excellent growing environment if you can’t grow in the dirt.  They involve an investment of both time and money, and therefore you should obtain the maximum benefit from their use.  If you put dirt from the garden in Grow-Boxes you defeat some of the reasons for having them in the first place, such as:
1) There are always multiplied thousands of weed seeds lying dormant in the dirt, just waiting for conditions favorable for sprouting.  Putting dirt in a Grow-Box creates that favorable environment, and you will have thousands of weeds, instead of NONE as you should.
2) The likelihood is also high that there will be some bugs and/or disease organisms in the dirt you use.  Put it into your Grow-Box, and suddenly instead of a pristine environment, you have the same problems of fighting bugs and disease as if growing in the soil.
3) By putting dirt in your Grow-Box you have the problems of clay soil, too sandy soil, etc., etc. – again minimizing the benefits of the Grow-Box environment.
4)  The weight of dirt in the box is between 2,000# and 2500# in a single 18″ X 30′ X 8″-high Grow-Box if used exclusively, and much more when saturated with water.  This will put substantial outward pressure on the box, and you will end up re-building your box many times over the years.  On the other hand, using sawdust and sand, I’ve seen Dr. Mittleider’s Grow-Boxes still perfectly usable after 25 years!
PLEASE, don’t try and figure out the best methods by trial and error!  It’s been done for you by the best!  Follow the procedures accurately as outlined, and you will have great success.

Will Sawdust & Peatmoss Decompose and Disappear?

Q. I was looking for a fertilizer substitute in my country (tropical), and I mentioned I was trying to grow in sand+sawdust mix. The person I talked to mentioned 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, but what he said made sense.  What are your experiences with this?

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

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

Why don’t my plants grow well??

Q.  It doesn’t seem to matter what kind of soil, soil amendments, or fertilizer I add to my grow boxes, my produce is consistently miniscule and non-productive.  When I dig up the soil, the boxes are full of tiny fibrous roots.  There are several very large trees next door-20-30 feet away from my garden area.  Could it be that these roots are from the trees and are sapping all the nutrients from my garden?  What can I do?
A.  There may be several reasons, either individually or acting in concert, that are causing your crop failures.  Let’s investigate each potential problem.


1)  Trees nearby may indicate too much shade.  Are your plants getting at least 6 hours of direct sunlight each day?  If not, you will not get much produce. 8-10 hours is better – especially for plants which produce flowers and fruit. 


2)  What is the soil composition, and what are you feeding your plants?  We recommend sawdust, peatmoss, perlite, and sand – in any combination you like, but with the sand being 25%-35% by volume.  That has no nutrition, so you need to feed your plants regularly.  One application of calcium as lime in a Pre-Plant Mix and regular small applications of a complete, balanced natural mineral nutrient mix we call Weekly Feed, will assure healthy, robust plants.


3)  How often do you water?  a raised bed or container will drain faster than ground-level soil, especially if you have lightweight organic materials as a major component.  Daily watering, until water seeps out the sides at the bottom is important to assure adequate moisture to the plants.


4)  If all the other elements are properly taken care of, it would take an awful lot of tree roots to keep your plants from growing, but it is possible.  Dig a shovel-width trench the length of your containers, between them and the trees, at least one foot deep.  This should cut most of the tree roots that have ventured that far.


5)  Are the trees walnuts?  Walnut trees have a reputation for producing a substance which is toxic to some vegetable plants.  Tomatoes do not do well at all near walnut trees.  If they are walnuts, you may well have that problem.

Treating or Painting Grow-Box Lumber

Q.  I am worried about using treated lumber to make my Grow-Boxes because of warnings about harmful materials in store-bought treated lumber.  What should I use?

A.  One alternative is to paint them with a good exterior paint.  The Grow-Boxes in Dr. Mittleider’s back-yard garden have been there for 25 years, with only occasional re-painting.
A second alternative is to make your own wood treatment.  The following comes from an article in a recent Organic Gardening magazine.
  • “Melt 1 ounce of parrafin wax in a double boiler (DO NOT heat over a direct flame).  [That’s a great way to start a fire]
  • Off to the side, carefully place slightly less than a gallon of solvent (mineral spirits, paint thinner or turpentine at room temperature) in a bucket, then slowly pour in the melted parrafin, stirring vigorously.
  • Add 3 cups exterior varnish or 1.5 cups boiled linseed oil to the mix, stirring until the ingredients are blended. When it cools, you can dip your lumber into this mixture or brush it onto the wood.”

    This should give you several years’ extended life for your Grow-Boxes.



What Size Boxes Recommended?

Q.  What size Grow-Box should I use? I have the original More Food From Your Garden, and the grow boxes are 5’x30′.  Now when I look on the website it says the boxes are 18″x30′.  Which is correct?  And why in the heck did you change the sizes?

A.  We grow in both 18″ wide and 4′ wide boxes now, but you can use any width you want.  Dr. Mittleider’s experience has just shown him that these two sizes work the best, for many reasons, which only 75 major projects and 38 years’ experience in 27 countries can teach.