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 www.foodforeveryone.org. 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 http://www.foodforeveryone.org 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 http://www.foodforeveryone.org

What direction should I face my Greenhouse?

Q. In "Grow Bed Gardening," Dr. Mittleider says, "In the nothern hemisphere, face the length of the building east and west. This gives the broadside a southern exposure and all plants get the maximum light when the days are short and the sun is farthest south."

In "The Mittleider Gardening Course," he writes, "If you have a choice, orient your Grow-Boxes north to south so the shadow changes as the sun moves from east to west."

These two statements appear to be contradicting each other, in that the greenhouse is supposed to be facing one direction, while the actual garden is built with rows going the other direction. Is this right, and if so, why is the garden different than the greenhouse, and how important is this anyway?

A. Strictly speaking both statements are correct. We believe that somewhat more light gets to the plants in a greenhouse with the long side facing the sun. And in the garden we prefer rows running north and south. However, over the years Dr. M. has determined that the direction - of greenhouses and rows in the garden - are not so very important. What is important is that there be no shade, either from fences, trees, shrubs, or buildings, or from other taller plants.

Just take care of those things and then orient your greenhouse and your rows whichever way works best for you.

More often than not it's the layout of the land and the watering situation that dictates the best direction for both greenhouse and garden soil-beds or Grow-Boxes. The greenhouse needs to be level, and if changing the direction makes that primary goal much easier or less costly, then you should do it.

If there is a prevailing slope to the garden, you will want to orient your soil-beds or Grow-Boxes in such a way that the water source is at the high end, and the rows will have a fall of no more than 1" in 30'.

This often requires putting your beds or boxes rows across the slope, rather than following the slope. The extreme example of this would be a hillside, with level rows terraced into the hillside.

Extend Growing Season 6 weeks both Spring and Fall

Extend Growing Season 6 weeks both Spring and Fall

Author: Jim Kennard

All who are interested in extending your growing season - particularly with vertical plants - may want

to save the following description of covered T-Frames. You can plant 4-6 weeks earlier in the Spring,

and harvest 4-6 weeks later in the fall if you do it properly.

In a garden with 18" X 30' beds and 3 1/2' aisles, place 8 T-Frames at 10' intervals in two adjacent

beds parallel with the inside stakes, so that the 4" X 4" posts are 3 1/2' apart. The top of the "T"

should be 32" long, and thus the width of both together is 6' 6".

For stability, nail each set of two T-Frames together - bridging the gap between them - with 6 1/2'

long 2" X 4"s. Next, tie all T-Frames together lengthwise using 6 - 10' 2 X 4's. Now you have a 6

1/2' X 30' greenhouse frame covering two Grow-Beds or Grow-Boxes.

Buy 32 - 3/4" 45 degree PVC elbows and 1" pipe straps. Nail or screw the straps and elbows at 2-foot

intervals along both sides of the 2 X 4 frame, with the elbows facing up and to the center of the

greenhouse.

Buy 16 - 10'-long pieces of 3/4" PVC Schedule 200 pipe, 16 - 3/4" pipe straps, and 4 - 8' pieces of 1"

X 2" lumber. Cut the PVC pipe and the 1" X 2" lumber to to 7 1/2' lengths. Nail the 1 X 2's

together, using the 6" pieces, making a single piece 30' long. Nail or screw the 3/4" pipe straps to

the 1 X 2" wood at 2-foot intervals, on the same side of the wood as the 6" pieces which hold the wood

together. Insert the 3/4" PVC pipes through the straps. With the wood on top, insert the PVC pieces

into the 45 degree PVC elbows - creating the arched roof.

Buy a roll of 6-mil 24'-wide greenhouse plastic at least 37' long (do NOT use construction plastic.

It will become brittle and tear within 3-4 months). Cover the greenhouse, with 3 1/2' overlapping on

each end.

Buy 8 - 1"-long eye bolts and 130' of 1/4" nylon rope. Attach eye bolts on the side of each T-Frame T

- 1" in from the edge and 1" down from the top. Cut rope into 8 - 16' lengths. Tie one end of rope

to each eye bolt. Hammer a 3 1/2" nail into the top of the 2" X 4" on the upper outside edge near the

eye bolt. Tie short loops into ropes at 10', 12' and 14' to give 3 levels of opening the sides of

your greenhouse plastic.

Buy 16 - 8'-long pieces of 1" X 2" lumber. Cut all to 7 1/2' lengths. Cut 2 into 4 - 3 3/4' lengths.

Place wood on both side edges of greenhouse plastic along both sides of greenhouse and screw

together, sandwiching the plastic between the two pieces of wood. Alternate lengths of 1" X 2"

between 3 3/4' and 7 1/2', to make the entire 30' length strong. Roll plastic sides up in warm

weather, and lower in cold weather.

Fold and attach plastic on ends to secure an air-tight covering in cold weather, and open when weather

is warm.

After a few of you handy builders have done this, you can help me improve the instructions, and

perhaps provide all of us with some graphic illustrations.

Heat Source(s) for Mini-Greenhouses

Q. In your answer on 'extending your growing season' you mention using a small heat source for the 'mini greenhouses'. What heat source would you recommand and how is the best way to use it?

A. Depending on the size of your Mini-Greenhouse and the severity of your frosts, you may be able to keep your plants from freezing by the use of a couple of lightbulbs placeda little distance from the ends. Or it may require a 1500 watt electric heater, generally turned to low heat. You will need to be careful that you don't cook your plants or melt the plastic. And always turn it off/unplug it when the outside temperature rises.

How to build a mini greenhouse with PVC

Building Mini-Greenhouses from PVC Pipe

Author: Jim Kennard

I will give instructions for building a jig and then making PVC arches for 18"-wide boxes or beds.
Materials needed:
11 - 5' lengths of 1/2" Schedule 40 PVC pipe - to place arches 3' apart - for each bed or box you are wanting to cover.

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).

The jig for bending the PVC 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 18" on the plywood and make 3 marks corresponding to the others. Draw lines between the marks.

Make marks 2" up from the bottom of both 18" lines. Drive nails into the 4 upper
marks, leaving 2" exposed. Drive nails into the marks 2" up from the bottom of the 18" lines, then drive nails 1" to the left and right of these nails.

Cutting and Bending 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. Place dirt on all sides of the plastic to hold it in place, as well as at the ends.

Whenever the weather is conducive, open the ends, and when it is above 60 degrees, take the plastic off from one side.

Remember, you must watch carefully that it doesn't get too hot in your mini-greenhouses. A thermometer in at least one bed is a good idea, to measure the temperature, and make adjustments in the exposure.

Remember also, that brassica's can grow in cooler weather than the warm- weather plants. Tomatoes, corn, peppers, etc. must be near 70 degrees or
above to do well.