Growing Through the Winter

A gardener asked the following question about building small greenhouses and growing in cold weather using information from the Mittleider Grow-Box Gardens book: “Since I am in zone 3 it would be very helpful if I could have the rest of the information the article referred to on “cold weather gardening” in chapter 12 if you think I need it. Is that the information that will tell me how to double-layer the greenhouse to have a 3-to-4 inch dead air space?”

Here’s my answer, which will be helpful to anyone who is building a greenhouse to grow in cold weather.

Chapter 12 of Grow-Box Gardens does indeed show and tell you how to double cover the greenhouse. I am sorry that Grow-Box Gardens is currently out of print and unavailable. Hopefully we can figure out how to get it re-printed inexpensively enough to have it available again by next growing season. In the meantime, let me tell you a few things the book says about winter gardening in cold climates.

Seedlings should be started in warmer weather and transplanted into the greenhouse by early fall if possible, so that much of the vegetative growth takes place before it gets cold.

During the cold months plants can be maintained and harvested at lower temperatures. It is important, however, to maintain soil temperatures above 50 degrees as long as possible, otherwise the plants will go dormant.

A greenhouse is important, and it should be double-covered, with a dead-air space of 2-4″. Building the greenhouse east to west, with the north-side wall built into a hillside or against an insulated wall, can reduce heating costs significantly, and even provide some heat from the mass of the north wall.

If you’re really serious about growing in cold weather, hot water pipes buried 4-6″ deep inside the greenhouse near the outside edges will provide some heat and ward off cold from the frozen ground outside.

If it is too cold to keep the entire greenhouse from freezing, consider a greenhouse within the greenhouse to protect valuable crops.

Arched PVC frames covered with 6 mil greenhouse plastic, with a small space heater inside, can keep a row or two of plants warm enough to save them even on very cold nights, if it is inside a greenhouse already.

If daytime outside temperatures rise above 65 degrees some ventilation should be provided in the greenhouse.

Using Greenhouses in Tropical Versus Temperate Growing Conditions

The question has been asked whether or not the height of greenhouses should be greater in warm climates – to allow for better/more air circulation.  The short answer is no.

To get free plans for building several styles of greenhouses visit and join the FREE MittleiderMethodGardening@yahoogroups.com, and go to the Photos and Files sections.

The height of the structure does not reduce air circulation.  The continuous ventilator along the entire roofline of the permanent seedling greenhouse lets hot air escape quickly.  Also, in warm climates the plastic on both sides is designed to roll up , to give excellent side ventilation.

The height of the structure was chosen to accommodate standard lumber lengths plus the reach of most gardeners. Seven feet is about as high as most of us can reach comfortably.

It’s also about the same height that tomato plants will grow before we cut the tops off 8 weeks before the first expected frost in cooler climates- where tomatoes and other warm weather crops are most likely to be grown in greenhouses – so they can mature all the fruit they have set.

For longer growing seasons such as in Central & much of South America, Africa, the Pacific Islands, and the Caribbean, let the plant turn over and come back down, rather than cutting it off.  This will require pruning leaves off the lower branches when fruit has been picked.

The in-the-garden greenhouse would be built the same in hot humid climates as in temperate zones, the way it shows in the YahooGroups pictures, except that you don’t keep the plastic all the way down except during a bad storm.

Rather than protecting plants from cold weather and frost, in warm climates the in-the-garden structure is mostly used to keep heavy pounding rains and hot direct sunshine from hurting tender plants.

In warm climates – and during mid-summer in temperate zones – I recommend you roll the plastic up to the top on all sides and tie it in place.

For additional shading if needed during the hottest part of the day, consider either throwing a 30-40% shade cloth over the top, or if the shade is needed for a long period of time consider splashing white-wash on the under side of the top plastic. Use material that will wash off when water is applied.

For more information on building and growing in greenhouses visit the archives of the Gardening Group.

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 https://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 https://www.foodforeveryone.org

What Direction Should I Face My Greenhouse – How About the Garden Itself

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.

Can You Recommend a Really Cheap Greenhouse That’s Good?

Q.  Many people tout their favorite greenhouse plans as the cheapest and best.  What makes the Mittleider designs better than the Hoop-House tunnel ones, or the glass paneled ones, etc.?  The permanent one in the Mittleider Gardening Course would be difficult and expensive to move, wouldn’t it?
 
A.  There’s cheap and there’s cheap.  The Foundation is very concerned with helping people do things the most economical way.  However, that is not always the cheapest way at the outset.
 
The greenhouse plans we give people don’t have to be “permanent”.  My greenhouse at Utah’s Hogle Zoo Garden is on Stirrups and is entirely screwed together for quick dismantling and removal; it’s covered with a single sheet of 6 mil greenhouse plastic; it has the best ventilation system of any comparable-sized greenhouse in the world, and it costs virtually nothing extra.
 
Anyone with a garden large enough to need a greenhouse of this size will be greatly blessed financially by doing it right.  There are many reasons why this greenhouse is better than the cheap hoop-type, given the sizes are comparable:
 
1) It’s structurally very sound, and will not be blown down by storms.
 
2) Strong built-in tables keep plants off the ground avoiding cold, wet, bugs, and diseases.
 
3) Built-in continuous ventilators in roof and sides keep plants cool in hot weather without electrical fans.
 
By the way, while the plans show a twenty by forty-foot greenhouse, it can easily be scaled down to any size that fits your needs.  Even an 8′ X 16′ greenhouse, that would be a real boon to the backyard gardener, is easily built using these plans.
 
And for those folks who only want an even smaller one, the Grow-Box Gardens book has a couple of plans that cost very little, yet are sturdy and practical.
 
These greenhouses have been built, tested, and proven highly effective in many countries throughout the world – from 60 degrees North latitude in Russia to 20 degrees South latitude in Madagascar – and many are still in use after 25 and 30 years.  Remember that initial cost is only a small part of the investment equation.

Free Greenhouse Plans – & Greenhouse Growing Instructions

Q. Does anyone have plans for mini greenhouses that you can build and start seed in to about 3 -4 feet tall?

A.  We have plans for greenhouses available free on the Foundation website. 

The plans for the recommended Mittleider-style greenhouse, with a “continuous ventilator” running along the peak of the roof, are available for the asking, just by sending me an email at jim@growfood.com.  The pictorial description of building the greenhouse is included in the free down-loadable chapter in the Books section of the website at https://foodforeveryone.org/grow_bed_gardening/, next to the Grow-Bed Gardening book.

And plans and explanation for a smaller, quonset hut-shaped structure are included in the free down-loadable chapter from the book Grow-Box Gardens.

All seven books have an important chapter included for your inspection and study, and we invite you to avail yourselves of the opportunity to learn all you can in this way.

The question is asked if a person can grow his plants to 3 or 4 feet tall in one of these greenhouses (and then presumably take them out to the garden), and I would counsel against it.  By the time your plants are about 12″ tall their roots are crowding a one-gallon pot, and the stems are susceptible to falling over, plus they take quite a bit of space for proper light.  If you are going to have them in the garden you should time the planting of the seeds to be no more than 12 weeks before that final transplant time.  the plants will be about 12″ tall, with strong stocky stems, if you have pruned and cared for them properly.

On the other hand, if you want to grow tomatoes, cucumbers, peppers, etc. throughout the growing season in the greenhouse, they should be transplanted into the final bed location by the time they are 8-12″ tall.  And they should be at or near ground level, rather than on tables at that point, in order to give them plenty of height to grow more than 7′ tall.

What Kind of Greenhouse to build

Q.  Are greenhouses really worthwhile?  And what kind should we build – quanset/tunnel, PVC, steel rebar, or wood, and what about heating and cooling?

A.  Greenhouses are an excellent way to give you between 4 and 8 weeks longer harvest period in your garden, as well as minimizing problems with pests and diseases, by allowing you to have strong, healthy and robust plants ready to place in your garden by the time others are just planting seeds.

Please consider three greenhouse issues Dr. Mittleider has dealt with – and the way he recommends they be handled.  While every family’s situation may be unique, there are several common elements, and we will discuss how to avoid three common problems.

In Dr. M’s book called Grow-Box Gardens (AKA More Food From Your Garden), chapter 10 is devoted to building small greenhouses, and the plans are quite thorough.  Go to the Store on the website, click on Grow-Box Gardens, and you can download and read the chapter on building a small Mittleider-recommended family garden-size greenhouse.  It has a strong wooden frame, supplemented with PVC, and that is the first issue I’d like to address.

We recommend you build your greenhouse to last, rather than have the first heavy snow load break it down, and so would recommend a wood or steel frame – at least for your main structure.

The second issue is heating/cooling and air flow, which is almost as important as the first.  Unless your quanset or tunnel-type greenhouse can have the sides easily rolled up, you will likely have problems with cooling in the summer months, because electric fans are expensive, and not always even available in gardens. 

The “Continuous Ventilator” running the length of the roofline on the current Mittleider-recommended greenhouse plan (Chapter 10 in Grow-Bed Gardening – free download in Store section) is the best solution, in our experience, since heat rises, and venting out the top eliminates the hottest air while drawing in cooler outside air from the sides and ends.  On large structures and in hot climates we also have at least one side able to roll up from table height to the roof line, thus increasing the venting to the maximum.  If flying insects are a problem we recommend screen be placed on all vent areas.

Thirdly, we recommend you make your greenhouse tall enough so that you can have all your plants off the ground on tables.  Some tunnel/quanset plans are very low, and plants are on or in the ground.  Using tables will help avoid problems with pests and diseases, which will spread like wild-fire in a greenhouse if they get started.

To summarize, I recommend the “continuous ventilator” wood structure design as my first choice, and as a second choice I would recommend the plan in chapter 10 of Grow-Box Gardens – making sure you allow for rolling up the sides for continuous ventilation.

Mini-Greenhouses to Extend your Growing Season

Simple and Inexpensive Mini-Greenhouses for Grow-Boxes and Soil-Beds

It’s not too early to begin preparing for early spring planting! By covering your 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 MittleiderMethodGardening@yahoogroups.com in the Photos section. The pictures show arches over Grow-Boxes. 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 – 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.