Greenhouses allow you to extend your growing season and have more plentiful harvests. With proper construction and plant selection you can grow all year long. There are a countless number of designs that you can find online. If you're like us, you've spent months researching greenhouse designs that would be both economical and easy to build.
Hoop greenhouses have several benefits over other greenhouse plans for effective growing all year long. We build our hoop houses on the coast of North Carolina which are prone to high winds and rain from hurricanes and tropical storms.
This free greenhouse guide was put together after building several greenhouses on our property. It will give you detailed plans on building a DIY greenhouse that minimizes cost and maximizes ease of build. It is our hope that you find these free greenhouse plans helpful.
How many plants do you want to grow? How much room do they take up? Do you want to bring equipment into your greenhouse? These are questions you need to ask yourself before you get started. Make sure you build a greenhouse with a size that best fits your needs. These greenhouse plans are for both a 6 foot wide low tunnel greenhouse and a 10-24 foot wide high tunnel hoop house.
The Low Tunnel Greenhouse stands 4 foot high and will be 6 foot wide. The low tunnel hoop house is a great choice when planting low-growing plants, including:
|Peas||Kale||Other Low Growing Plants|
The high tunnel greenhouse plan can be built anywhere from 10-24 feet wide and approximately 6.5 ft (easily adjustable to 14 ft or higher for 20-24 feet wide) high structure. A high tunnel quick hoop house is an ideal choice if you plan to have a walk-in greenhouse. These are great if you want to have a wide variety of plants or want to be able to work inside of your hoop house.
In the heat of summer or climates in hardiness zone 8 or higher, greenhouse ventilation is critical. If you don't want your plants to cook in the heat, we absolutely want roll-up sides with a hand crank. This allows you to easily manage the venting. We also recommend roll-up sides with a hand crank for all low tunnel hoop houses as it allows for easy access to your plants from the sides.
During the intense summer heat, we may need to throw a shade cloth on top of our greenhouse to keep it cool and reduce the solar radiation. In the frigid winter, we can consider adding another layer of greenhouse film for extra insulation. Check out this great video from Dr. Nate Storey at Bright Agrotech on double layer greenhouses if you live in an especially cold environment.
First, pick an area that is flat and not prone to flooding (More information can be found at Selecting the Ideal Location for your Greenhouse). If you have an existing greenhouse on your property you want to make sure it is at least 8 feet away from existing one.
Tools Needed (See the complete list of Greenhouse Tools)
Our instructions assume ground posts and bows every 4 feet. We sink the ground posts 2 feet into the ground, allowing for higher tunnels and stronger frames. 20-24ft houses in high wind areas should make deeper ground posts and secure the plastic lock channel with extra screws.
Start by placing your first marking stake at least 8 feet away from an existing greenhouse or other small structure. For larger structures such as a home you will want to place your greenhouse significantly further away.
Lay down weed barrier if you prefer. (This is optional depending on your needs.)
Secure the weed barrier with garden staples or dirt.
Making Your Greenhouse Square
Mark each corner of your planned greenhouse area with any kind of marking stake - First measure length to length (its best to stick with lengths divisible by 4'). The width should be 10, 12, 20 or 24 foot for our high tunnels. Then measure diagonally, making sure the diagonal measurements are equal to each other. Double check that each length, width and diagonal measurements are equal.
This ensures your greenhouse will be square.
Once your area is measured out, place a temporary stake to mark the location of each corner as this will be where your first ground posts are located.
Pre-Cutting Greenhouse Ground Posts (If not using ourground posts)
To make the job much quicker cut all your ground posts ahead of time. These high-tunnels require 1 5/8" fence line posts found at the big box hardware stores.
To calculate the number of posts you will need take the length of your greenhouse in feet and divide it by 4 and then add 1. This gives you the number of hoops you will have.
Example Length = 100 feet. (100 ft / 4) + 1 = 26 hoops. 26 hoops = 26 pieces of fence line posts.
Cut each into (2) 48" pieces for 10'-24' greenhouses.
We recommend using a reciprocating saw with a vice to hold the poles in place while cutting, and you should be finished in about an hour. A hacksaw will work too but it is much slower.
After all the ground posts are cut we want to mark both the depths to drive the post into the ground and the hole for EMT hoop attachment.
10-24 ft Wide Hoop House
Mark the pole down the middle at 24". Put an X on one end which will be the end in the ground. On the above ground end you will be drilling two holes. Make sure these holes are perpendicular from each other (90 degrees away from the other hole). Drill the top hole 2" from the top with a 1/4" bit. Spin the pole 1/4 of the way around. Drill the 2nd hole 23" from the top with the same drill bit.
You will first install each corner ground post. Place your posts where you had previously marked the corners and begin driving those into the ground. When driving your ground posts make sure you use a Ground Post Driver. This will prevent your pole from becoming warped.
While driving the posts into the ground you want to make sure the poles are level in all directions. As you are driving the pole into the ground check for levelness on the front and sides and adjust as needed. Also pay attention to those holes you drilled. The top hole needs to be facing in the direction of your ground posts (if you were really talented you would be able to shine a laser light from one end of the greenhouse to the other passing through all the holes). The bottom hole should be facing toward the inner part of the greenhouse.
Once corner ground posts are installed re-measure length, width and diagonally one last time. If you made a mistake it's not too late to fix it without too much work. Once you are satisfied tie a string line around the outside of the corner posts. This will help to keep all your ground posts in alignment so you don't get wavy hoops later on.
To further help to keep your ground posts straight use a 6', 10', 12', 20' or 24' (same length as the width of your greenhouse) piece of lumber as a guide for measuring an equal distance between each ground post. This saves measuring each time and ensures the greenhouse is exactly the same width for the entire length. In conjunction with the string line, this will help to keep the top and bottom of your ground posts in a straight line.
Install each ground post 4 feet apart. As long as you chose a multiple of 4 as suggested earlier your poles should be evenly spaced. If you are building a longer greenhouse it may make sense to create a jig out of a piece of dimensional lumber and cut out notches 4 feet apart that your poles can fit into.
For baseboards we use 1" x 8" x 8' white-wood ledger boards. This will be in contact with the grounds so some people like to use pressure treated wood here. You could, however, but we don't because of the harsh chemicals that are used to treat the wood. Pressure treated wood contains chromium, copper, and arsenic. Government studies have shown that these chemicals can leach from the wood into your soil. We don't want this anywhere near our food.
For the first baseboard we cut off the first 1 foot so that a board doesn't end on a ground post. Line up the cut board with the front of the first ground post. Clamp the board to the post and use your 1/4" drill bit and drill through the wood by going through your previously drilled hole in the ground post.
Insert a 4" x 1/4" Tap Bolt & tighten with a washer & nut on the outside as pictured.
Where two pieces of wood butt together connect them with a scrap piece of 1" x 8" and attach with 1.5" wood screws (Phillips flat head #7). Be sure not to overdrive these screws as you don't want the screw tip poking out the other side as it could pierce your greenhouse plastic.
Once you have all the side baseboards attached you can install the baseboards on the end walls with a 2" x 6" x 8' board and a carriage bolt, or you can do this later while building the end wall.
Lay out the poles with them all facing with the 'swagged' (male) end in the same direction. Mark each pole at 9" on both ends.
This mark will tell us where we insert the pole into the hoop bender and how far to insert our poles into the ground posts.
Securely attach the hoop bender to a table or bench. Your hoop bender should come with screws or bolts to anchor it in place.
Slip each pole through the holding strap on the hoop bender and push the pole up to the mark you made. Bend the pole every 18". We laid out some scrap pieces of wood on our bench so that the pole stays level while bending. You want to try to keep the pole from twisting while you bend. When you reach the end of the pole find a scrap piece of pole with a male end to use as a pole extension. This will make bending significantly easier.
Note the following:
After bending the poles, join male and female ends and screw together with 3/4" self-tapping screws. (Be sure not to place the screws on the top of the hoop where it would rub against the plastic.)
Start inserting all your hoops you built into the ground posts. Use the line you previously marked at 9" to know how far to push your bows in. You should expect your hoops to be a little wider than your ground posts. This is perfectly normal as you will just bend them in a little as you get each end of the hoop into the ground posts.
After setting all of the hoops into place, you may have to adjust some of these in or out to make all of the hoops look even when viewing it from the ends.
Once satisfied use your 1/4" bit to drill through the hoops (at your pre-drilled hole) in the ground posts. Attach with a 2" 1/4" hex bolt with washer and nut.
Once all hoops are secured in place, begin inserting your ridge pole into the cross connectors or spring slips. You will be using 1-3/8 cross connectors.
Center all your cross connectors in the middle of the hoop which should be the highest point.
10-24 ft Greenhouses: You will be using the same 1-3/8" fence top rail poles you used for the hoops as ridge poles. Slide each pole through the cross connectors and connect each ridge pole together by inserting the male end into the female end and securing with a 1/4" screw (again from the side or bottom but not the top).
Stand back away from your greenhouse and adjust left or right until the whole connected ridge pole is straight.
Before tightening the screws on the cross connectors, ensure each bow is 4 ft from each other then tighten or screw the cross-connectors. Be sure to screw from the side and not the top as you don't want your plastic to get caught on the screw.
Make sure each end of the pole is flush with the end of your greenhouse by cutting off the excess from one end with a hacksaw. You don't want any excess sticking out as it could get caught on your plastic.
We also like installing duct tape on the ends of the ridge poles. This will prevent the plastic getting hung up on any sharp or protruding edges.
There is no hard rule as to where you should place your hip boards. You want to set hipboards as high as you want your roll up sides to go.
**If you are not using roll-up sidewalls, you still want to install the hipboard for stablility, However, it gets mounted on the INSIDE with the bolt flush with the outside, so it doesn't interfere with the plastic.
For our hoop houses we typically place the bottom of the hip board about 36 inches (usually a little higher for larger greenhouses) from the top of the ground post. Mark each hoop at your desired height (I like to mark from the top of the hip boards as it's easier to see).
Similar to your baseboards you want to cut the first 1 foot off your hip board so the butt joints don't land on a hoop.
Hip Board attachment : Line up your boards on the marks and use a clamp to hold in place. Drill a 1/4" hole through your board and then through the hoop. Place a zinc plated 1/4" x 4" carriage bolt through the wood and attaching with a washer and nut on the hoop end. **Note board will go on the inside if you don't plan on using roll up sides.
The wiggle wire channel can now be installed on the hip boards if you have roll up sides, otherwise on the baseboard. (Further wiggle wire installation information can be found here) It is helpful to pre-drill the holes before installing (at least 4 holes per 6.5′ piece, 6 in higher wind areas and on larger sizes). Be sure that the lock channel is installed straight from one piece to another. If the wiggle wire lock channel is not straight it can create corners where it butts together and the plastic may snag.
Once the channel is installed on the hip board (and or baseboard), install wiggle wire channel on the first and last arches (over the entire hoop but not over lapping the hip board), using a clamp to help you keep the channel in place while you bend it along the curve. Your lock channel should easily bend to the curvature of your hoops.
There are many ways to build end wall doors. Searching online you will find an endless number of ways to do this however we are providing what we find to be the easiest.
If you haven't already done so now is the time to install the baseboards on the front and back of your greenhouse. Simply run the baseboard the entire length of your greenhouse and attach to your baseboards that ran the length of your greenhouse. Connect to the end ground posts using a 4"x1/4" carriage bolt.
Installing the Door Frame
You will want to make sure that your door is wide enough to fit a wheelbarrow or tiller through.
Determine the height you want to make your door. Add an extra 7/8" to account for the reveal around the top (3/8") and bottom of the door (1/2"). Measure up from the baseboard along one of the inner door frame boards to that measurement and make a mark. Repeat for the opposite side as well.
Cut a 2" x 4" to fit in-between with the bottom lined up with your marks. Make sure your header is level using a level and adjust as needed. Secure your header using 2.5" wood screws by screwing to your posts. Cut another 2" x 4" to fit directly above your header to form an L as a header. This should be flush with the outside of the lower header piece. Secure this piece with the 2.5" wood screws as well.
Now you want to install posts on the sides to form an L similar to how you did the header. These provide areas to secure your wiggle wire lock channel later on. The easiest way to measure these side posts is to place the bottom on the ground and just mark underneath the hoop and cut. Secure these additional side posts with the same 2.5" wood screws.
To build the door frame use two 1" x 4" boards to create a door frame. The width of your door should be 3/4" shorter than the opening and length 7/8" shorter. This allows for 3/8" of expansion on each side and top of your door when it gets wet. Allow for 1/2" expansion on the bottom of your door. To provide your door some support we sandwich plastic and chicken wire between the two 1" x 4" boards. You also want to add a 1" x 4" board in the middle of your door for stability, Install your door with some zinc plated hinges, making sure while installing to keep the spacing between the door and frame even.
After your door is installed place your lock channel around the frame of your door.
First, make sure you can finish securing the plastic before you end for the day so it doesn't blow away on you.
Roll the plastic out and drape over the length of the greenhouse, equidistant from each end. Securing the plastic only on one end by installing the wiggle wire from the top of the arch to the hip board.
Once the plastic is secure on the first end arch move to the opposite end and secure the greenhouse plastic in the arch the same way. Pulling the plastic tight as you go. Just install the wiggle wire down to the hip board. We will install the remainder of the wiggle wire after we complete the roll up sides.
Now is the best time to install your roll-up sides. Doing this now will help pull down the plastic tight before the wiggle wire is installed on the hip-boards. This will ensure even venting when the hand crank is used.
Connect 3/4″ EMT conduit along the length of each side of the greenhouse, using 3/4" couplings to connect the pieces together. Extend the EMT a foot past the edge of the greenhouse on both sides. If you are using our 3/4″ couplings, use self-taping screws to secure the poles together.
If you are using a standard EMT coupling make the screws as tight as you can to prevent slippage. Roll the ends of the plastic around the connected EMT until the greenhouse plastic is tight and the pole is flush with the bottom of the greenhouse.
Install snap clamps every 2 ft to ensure even ventilation. Put a screw through each snap clamp for permanent installation. After all the snap clamps are secure, the greenhouse plastic should be hanging down taught.
This is the time to install the rest of the wiggle wire onto the hip boards. Work your way down from one end to the other. The plastic should already be somewhat taught from the weight of the EMT conduit.
When the length of the greenhouse has all of its plastic secure, now is the time to move to the front and back of the greenhouse to secure the plastic. If you find that the plastic is not tight enough hopefully you used wiggle wire. You can simply just wiggle the wire out of the channel. Pull the plastic tight and reinstall the wiggle wire. If you stapled your plastic to your hip boards you may be better off just leaving it.
Use the wiggle wire to install the plastic on the end walls, in the same manner as before, starting from the top and working down towards the ground. The plastic will need to be cut in half to be used for each end.
You can install the greenhouse ventilation gear crank now. The wiggle wire should be secure on the top ends and at the hip board all along the sides first. The EMT on the roll up sides should be extending a foot past the greenhouse on each end. You will just have to eye this one out a bit, but it's very simple.
There are different ways to secure the guide rail for the hand crank, but all I did was take a scrap piece of 1" EMT, about 3-4 ft, and hammered that into the ground near the edge of the 3/4" EMT conduit. I then put a 6 ft piece of EMT conduit about 2 ft down into this pipe and put in 2 screws at ground level to secure it.
Put your hand crank on the guide rail, slide in the 3/4″ conduit, drill a hole and use the included screws to secure and you’re done!
Here’s a 12 ft x 100 ft tunnel shortly after construction: