Simple and Inexpensive Mini-Greenhouses for Containers and Soil-Beds

It’s not too early to begin preparing for early spring planting!  By covering your containers, which we call Grow-Boxes, or Soil-Beds with “Mini-Greenhouses” using PVC arches and greenhouse plastic, you can be in the garden with cool-weather plants by the end of February or the first of March.  They will warm the soil and protect your plants from light frosts.  This is often enough to extend your growing season by several weeks in both spring and fall.

Pictures can be seen in the Photos section of the free MittleiderMethodGardening Group. Invitations to join are on every page of the Food For Everyone Foundation website at The pictures show arches over Grow-Boxes, or containers. Following are instructions for building a jig and then making PVC arches for 18″-wide boxes or soil-beds.

Materials needed:

11 – 5′ lengths of 1/2″ Schedule 40 PVC pipe – to be placed 3′ apart in each bed or box to be covered.

6-mil greenhouse plastic – 5′ wide and 33′ long – one for each bed or box to be covered.

For Grow-Boxes only – 3 10′ lengths of 3/4″ Schedule 200 PVC pipe, cut into 24 15″ pieces for each box to be covered. Plus 22 2 1/2″ nails and small 2″ X 4″ block.

One 30″ X 30″ (or bigger) sheet of plywood, plus 6 – 2 1/2″ nails.

One heat gun (to heat and bend pipe).

With a pen, make 3 marks at the top of the plywood sheet – one in the center, and one each, 9″ to the left and right of the center. Go down 9″ on the plywood and make 3 marks exactly corresponding to the first 3. Draw lines from the outside lower marks to the top center mark. Place marks on both lines 10″ up from the bottom. Go down 27″ from the top of the plywood and make 3 marks corresponding to the others. Draw lines between the 9” and 27” marks. Make marks 2″ up from the bottom of both 18″ lines. Drive nails into the 4 upper marks, leaving 2″ of nail exposed. Drive nails into the marks 2″ up from the bottom of the 18″ lines, then drive nails 1″ to the outside of these nails. This is the jig for bending the PVC pipe.

Cut 5′ lengths of 1/2″ schedule 40 PVC pipe. Mark them at 18″ and 28″ from each end. Place one end of PVC pipe between nails on one side, with the end at the 18″ mark (2″ below the first 2 nails). With heat gun, heat PVC pipe at each spot where PVC pipe encounters a nail, and carefully bend the pipe to fit the jig. Allow to cool before removing pipe from jig.

For Grow-Boxes, place 15″ pieces of 3/4″ PVC adjacent to the Grow-Box at each end and at 3′ intervals on both sides. With a hammer, and using the small 2″ X 4″ block of wood, hammer the PVC into the ground until the top is level with the Grow-Box. Pre-drill a hole through the PVC pipe 2″ up from the dirt, and hammer the 2 1/2″ nail through both pipe and Grow-Box. Bend the nail over on the inside of the Grow-Box to avoid getting scratched later. Slip the 1/2″ PVC arches into the 3/4″ PVC holding pipes until they encounter the nails – about 6″ deep.

For Soil-Beds, just push the 1/2″ PVC arches into the ground at the peak of the ridge on each side of the Soil-Bed – again about 6″ deep.

Lay the 6-mil plastic over the entire box or bed, centered, with 18″ overhang on each end. Fold excess plastic to avoid a messy appearance. Place dirt on both sides of the plastic to hold it in place, as well as at the ends.

Whenever the weather is above 50 degrees, open the ends, and when it is above 60 degrees, lift the plastic from one side and lay it in the aisle.

You must watch carefully to ensure that it doesn’t get too hot in your mini-greenhouses. A thermometer in at least one bed is a good idea, in order to measure the temperature and make necessary adjustments. Note also that brassica’s (cabbage, cauliflower, etc.) can grow in cooler weather than the warm-weather plants. Tomatoes, corn, peppers, etc. must be near 70 degrees or above to do well. © 2006 – James B. Kennard

Jim Kennard, President of Food For Everyone Foundation, has a wealth of teaching and gardening training and experience upon which to draw in helping the Foundation “Teach the world to grow food one family at a time.” Jim has been a Mittleider gardener for the past twenty nine years; he is a Master Mittleider Gardening Instructor, and has taught classes and worked one-on-one with Dr. Jacob Mittleider on several humanitarian gardening training projects in the USA and abroad. He has conducted projects in Armenia, America, Madagascar, and Turkey by himself. He assists gardeners all over the world from the website FAQ pages and free Gardening Group, and grows a large demonstration garden at Utah’s Hogle Zoo in his spare time.

Gardening Books, CDs and Software are available at

Carrots are Bitter – What’s Wrong?

Q.  My carrots taste bitter, what’s wrong?   I am watering for 20 to 30 minutes using a drip system 3 times per week.  I use the Mittleider organic method of growing, and grow in containers, or Grow-Boxes.

A. Your problem is a lack of water.  You need to water daily until you see water coming out the bottom of the container or box.  I’ve never seen a soaker hose that would adequately water a sawdust/sand grow-box in 1/2 hour.  And it will dry out too much if you only water every other day. 

If you were growing in the soil, water still would most likely be the culprit, although if you are not feeding accurately and doing so every week for 5 times, you also might have a nutrient deficiency.  Be sure you are using the Mittleider natural mineral nutrients as fertilizers.  You can mix your own from formulas on the website, or get them pre-mixed.  Look at in the Store under Materials.

I recommend you automate your watering using the PVC pipe system taught and demonstrated in the Mittleider gardening books.  This system is inexpensive to build, it waters very accurately, and will last practically forever, if you take care of it. 

The books are available at, and you can even download the chapter of the Mittleider Gardening Library free, by going to the Store section and clicking on that book.

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