How to Build a Garden Low Tunnel (for Free)

low tunnel complete
Low tunnel ready to protect plants from endless winter.

Like many Minnesota gardeners, I’m getting itchy to put some plants in the soil. I have lettuces and greens under lights in the basement and some tomato seeds planted, but not yet germinated, in a warmer spot upstairs, but that’s not the same. It’s still pretty cold here and as I write this post on Friday afternoon it is snowing. Ugh.

Given the rather gloomy forecast, I decided to take things into my own hands and build a low tunnel where I could plant out greens and keep some of the seedlings as they get growing. I’ve been reading a lot about season extenders in the past year or so. We had a great article by Colleen Vanderlinden on them in the September/October issue of Northern Gardener and I recently read with enthusiasm Barbara Damrosch and Eliot Coleman’s new book The Four Season Garden Cookbook, which includes lots of practical tips on using cold frames, movable greenhouses and low and high tunnels to grow food in colder climates.

One of the designs involved using welded wire fencing and plastic. I had both on hand and knew I could fashion something serviceable pretty easily.

plastic ties
To make a longer tunnel frame, I joined two sections of fencing with plastic zip ties.

Here’s what I did: I took a length of 4-foot tall welded wire fencing and cut it in two equal pieces using a bolt cutter, making the cut in the middle of a square so that each end had a little tail on it. (Careful, these are sharp.) The raised bed I have the tunnel over is about 3 feet wide by 8 feet long, and the two welded wire pieces were about 4 1/2 feet across — just enough to create a bend for the greenhouse effect. I joined the two pieces to form one long one using plastic zip ties.

Next, I laid a painting drop cloth on the floor of the garage and put the wire tunnel on top of it. (If you have a heavier grade of plastic sheeting, use that.) I pulled the sides up and attached the cloth by poking the wire tails through the plastic. I left as much plastic as I could on each end of the tunnel and on the sides. I plopped it on the bed.

tunnel in plastic
Sheathed in plastic, the tunnel is ready to go to the garden.

Now came the tricky part. We live in an area that is really, really windy, and I knew I would have a flying low tunnel if it was not secured. I ended up doing two things. On each end of the tunnel I placed a piece of 2-by-10 lumber about 3 feet long. (I happened to have these on hand from another project.) Then, I took some rope and lashed the plastic down in three places, tying the ends of the rope to some winter-sowing jugs. Any fairly heavy plastic jug with a handle to tie the rope to would work. Voila!

The tunnel stood up to a fairly stiff breeze last night with no problems. I’ll start planting seeds and putting out seedlings on Sunday, when the weather is predicted to be a bit warmer.

It’s rare that I have all the equipment on hand for a project like this but this time I did.  There are many videos on youtube about hoophouses and tunnels. While the production quality isn’t great, this one has good step-by-step information on how to put together a low tunnel using PVC pipe and plastic.


Hardening Off: Seedlings on Wheels

Ready to roll back into the house!

I haven’t written much about seed starting this spring, because I’ve cut back on the number of plants I’m starting. After several years of seed-starting efforts, I’ve figured out that I do best starting tomatoes, Yvonne’s giant salvia and maybe a few brassicas (this year, Chinese cabbage and broccoli Romanesco). The brassicas are in the garden already, but the rest of the plants are still on my seed-starting shelf — which is a cheap metal shelf unit from which hang shop lights with fluorescent bulbs.

The seedlings started in the basement, but I was neglecting them, so I moved the shelf up to my office, which is now on our first floor. During the move, an inspiration struck — put the shelf on wheels! A quick trip to the local hardware store got me the wheels I needed, and today I wheeled the seedling cart from the office out to the deck for a couple of hours of fresh air. So easy! So quick! This might make hardening off, which I normally consider a huge pain, fun.

Hardening off means gradually acclimating seedlings to the outdoors. It is best done over a couple of weeks. (Northern Gardener has a good article by Colleen Vanderlinden on how-to harden off in the March/April issue.) I tend to rush the process because it’s such a pain moving all the plants in and out. With the wheeled cart, I can easily bring the plants out or in, depending on the weather and the sun. Hopefully, this will mean stronger plants when the time to put them in the ground comes.

Garden Recycling

I was going to call this post “Putting the Garden to Bed,” because that fancy climbing apparatus now adorning one of my vegetable beds is a headboard.

This is one of my dad’s clever ideas: Instead of buying a more expensive bed with a headboard, you build a headboard and attach it to the wall behind a mattress and box spring. More than a decade ago, he made two of these — one for each of my daughters. They looked really cute in a bedroom for little girls, but you know what happens to little girls — they grow up. So, the headboards were traded in for a more mature look a few years ago. We gave one away, but the other one had been in our basement.

It’s too nice too just collect dust, so I decided to recycle it in the garden. I attached it to the back of the raised bed with some deck screws, so the total cost of the project was $0. While it is shorter than most trellises, I think it will be attractive and useful. Birds love places to perch during the winter, and I enjoy watching the blue jays, cardinals, red-tail hawks, and other birds that frequent our garden during the fall and winter. Second, I think the headboard will work great for shorter climbing plants, such as this cucumber, or for plants the like the climb and tumble too, such as ‘Spitfire’ nasturtiums, which could grow up one side and down the other. It would also be a convenient place to tie tomato plants.

What’s your favorite example of garden recycling?

Deck Garden, Year 2

Deck garden today (that's my brother's foot in the corner.)

Last summer, I wrote two posts (here and here) on how to build a garden box for a deck, based on the one created by my sister and her husband. They hosted a barbecue on the 4th of July this year, and I got a chance to see how the deck garden is doing in its second year.

The answer: great! They planted different tomatoes this year, opting for slicers rather than cherries, and have plenty of green ones on the two plants growing in the box. They also have several beautiful looking basil plants, as well as oregano, parsley, rosemary, and chives. All of this is just outside the door to the kitchen, making it convenient to snip a few herbs for cooking projects. The deck box, which is made of cedar, remains attractive, despite heavy rains this year and its sunny location.

A $10 Greenhouse

Functional, not elegant.

Maybe greenhouse is an overstatement, but the recent cool weather plus my indoor seed-starting area getting over crowded required a spillover space for plants. There are many ways to fashion cold frames and hoop houses, and dozens of smallish greenhouses available for purchase. But I was looking for a quick way to get some of those darn pots out of my basement.

Here’s what I came up with: One of my raised beds has a decorative (also useful) trellis at the back of the bed. Before going to the store for the rest of the gear, I weeded this bed thoroughly. Then, I bought three scrap boards at the local big box ($ .49 each) and screwed them together with deck screws in the same way I have built raised beds before.  The box serves two purposes: it provides a little extra protection around the plants from wind and it gave me something to attach the top of the greenhouse to.

For the top of the greenhouse, I bought a  3 mil. paint cloth ($3.99). I had other paint cloths at home, but wanted the thickest grade I could find for strength.  To attach everything together, I found a cheap ($4.99) set of spring-fired clamps. I set the 3-sided box on top of the raised bed, then cut small slits in the plastic to slide over the top of the trellis. I arranged the plastic so it covered most of the back of the trellis and flopped over the three-sided box. Using the clamps — which came in two sizes — I attached the plastic to the frame. The plastic is not completely sealed so air will flow through the set up but the extra protection should also hold in heat. On hot days, I can peel back the plastic and clamp it to the trellis to keep it out of the way.

While the system is not beautiful, it seems to work. When I went out this morning, after a night where temperatures sunk below 40 degrees, the plants looked good. I made one additional modification, though. The plastic was not tight enough and was flopping on some of the plants, so I put a tomato cage at the end of the box opposite the trellis and tightened the plastic slightly in another place. The forecast calls for “breezy and cool” so I will be monitoring the set up to make sure the plastic stays where it belongs. I’m expecting the greenhouse will only be needed for a couple of weeks.

Vegetable Garden on the Deck? You Bet!

Squaring the boards up.
Squaring the boards up.

My sister and her husband have a large, sunny backyard, but they prefer to leave that space open for pickup football games and other neighborhood fun. (They have four children of their own and lots of little visitors.) So, when they decided they wanted to grow some vegetables, the solution was to build a deck-side garden. My brother-in-law, John, is an engineer, so he had no problem coming up with a good-looking, efficient design. It’s also easy enough to construct that you don’t have to be an engineer to build one. So, here’s John’s Deck Garden — and thanks to my sister, Elly, for sharing the photos. (By the way, these are larger photo files, so feel free to click on the thumbnails to get a closer look at what’s happening.)

Attaching boards to the supports.
Attaching boards to the supports.

John and Elly wanted a garden large enough to grow a couple of tomatoes, some basil and a few other herbs, so they decided to build a box 6 feet long by 2 feet wide. After buying 1-by-8 cedar boards for the sides, some 2-by-2 lumber for the support pieces and a piece of plywood for the bottom, John (with assistance from my dad) went to work. He cut the lumber to size, then used wood glue to attach the boards on top of the plywood bottom (top photo).  He started building the box, attaching the side pieces to the supports using deck screws. (This is where having two people working makes the job much easier.) He built it one layer at a time, so that the final box is about 22 inches deep.

2-by-2s raise the box off the deck.
2-by-2s raise the box off the deck.
Plenty of room for roots.
Plenty of room for roots.

Once the box was complete, John flipped it over and attached four strips of 2-by-2 to the bottom to raise the deck garden off of the deck. It’s not shown in the photo, but he also drilled some drainage holes in the bottom and lined the box with landscape fabric. The fabric helps the bed retain some moisture and the holes make sure it doesn’t retain too much.

Nothing beats fresh herbs right outside the kitchen door.
Nothing beats fresh herbs right outside the kitchen door.

With the box ready, John and Elly filled it with a mixture of top soil and compost and planted their tomato and herb starts. The photo at right was taken right after planting, and I’ve since heard that the plants are all doing well and the tomatoes have gotten big and already have blossoms. What a great way to raise vegetables in a small space!

A Beautiful Easter and a New Raised Bed

What a nice day it was on Easter! The weather was near perfect as we attended Mass, had a nice dinner with the girls, went for a walk in the Carleton Arboretum — and, oh yes, in between those activities, I built a new raised bed for my vegetable garden.  I mention all the other things I did Sunday to emphasize how easy it is to build a raised bed for your garden.

Raised beds are essentially wooden boxes to which you add soil and compost. The advantages of raised beds are many: They look neat, you can control the soil better, you’ll need less water, they produce more per square foot, they tend to heat up a little faster because they are above ground, and it’s a bit easier to set up fencing to keep critters away from your garden. If you are a beginning vegetable gardener and are not sure about the quality of the soil in your yard, raised beds are the way to go.

Upside down and ready for installation.
Upside down and ready for installation.

I had purchased the lumber for my bed a week or so ago. Because I wanted a little extra height, I bought three 2-by-10 inch boards, about 10 feet long,  and three 2-by-4 inch boards of the same length. The guys at the lumber yard cut one of each width of board in half, so I ended up with two short boards and two long boards of each type. To build the box, I measured and drilled pilot holes for each point of connection. (Drilling pilot holes is the key to getting things together fast.) Then, using deck screws, I attached the boards to each other. When the basic box was together, I added some 2-by-4s I had around as corner pieces. The whole job took less than two hours. (Truth in advertising: My first raised bed took all day to build — but I did not know about drilling the pilot holes then!)

There are several instructional pages on the web and Patti Moreno has an instruction video on raised beds, which is worth watching. Grab your tools. This is a great project for those weeks before you can plant.

Condo for Bees Open

Unlike so many condos for people, I am hoping my just completed condo project for orchard mason bees will soon be abuzz with activity. I’ve been meaning to build one of these since I read an article in Fine Gardening about raising raspberries and the importance of orchard mason bees as pollinators.

Last fall, we had an article in Northern Gardener on the honeybee crisis. Honeybees, which are responsible for much of the pollination of commercial crops such as almonds, have been dying off in large numbers. Marla Spivak of the U of M is a bee expert, and she believes several factors may be causing the die-off, including mites or diseases and changes in habitat, such as prairies becoming residential areas and large monoculture crops (corn). If you are interested in honeybees or just want to see pictures of people with bee-beards, please check out the U’s great Bee Lab web site.

Well, no matter what the situation with honeybees, gardeners need bees of all types for pollination. Orchard mason bees are perfect bee neighbors. They are not social bees–each little bee wants her own condo. They are very gentle and pollinate like crazy. To build the house, you need a block of wood deeper than 4 inches (see comment below) of any length (mine is about a foot) with an angle cut on one edge. You also need a spare piece of wood or a cedar shingle for the roof, and another piece of wood to mount the house on. If you are lucky and have a friend with lots of spare lumber and a rotating arm power saw, the job is a snap. (Thanks, Steve!)

Once you have the wood, you drill holes 5/16th of an inch in diameter about 3 inches into the wood. Drill as many holes as you want, but there should be about 3/4 of an inch center to center between the holes. I got 28 on my block. Then, attach the roof to the block, and the block to the mounting piece and you are ready to hang your bee house. The bees like it facing south, so I mounted mine on one of the posts of my pergola. The bees use the holes in the house for nesting. They love pollen from apples and raspberries and I have both very close to the bee house. With any luck, the bees will help produce a good crop of raspberries, apples, veggies, flowers, and more bees this summer.

Fun with Wood

It’s still too early to be tromping around in the garden, so the great weather on Saturday seemed like an invitation to finish some garden building projects. So, after picking up some deck screws and 2-by-2 posts at the local lumberyard, I started work on my new raised bed. (I bought the cedar for the sides last fall.) This bed will be 3-feet-by-5-feet and will be devoted to tomatoes.

The raised bed, upside down and waiting for installation.I’ve built raised beds myself twice before, and several years ago, my dad built a pair of them at my old house. His beds turned out nice and square–mine, not so much. I followed the guides set out by Sunset books on how to build the bed. I liked the idea of putting the posts down and basically building the bed from the top down. To put it together, I used deck screws. It worked better for me to drill a pilot hole for the screw, then to put it in and use my power drill to install the screw. This bed is 11 inches deep, with a 3-1/2 inch board on top and a 7-1/2 inch board underneath. (In the photo, it’s upside down.) On the next sunny day, I’ll go out and dig the holes to fit the posts in, and fill the bed with soil. The mix that I have heard recommended is one-third garden soil, one-third compost, and one-third sand. The Sunset guides indicate you can put the bed together in a few hours, which proved true. However, I’d recommend having someone around to hold the boards in place while you are attaching them. With the long boards especially, it’s tricking to keep them in position without a little help–hence, my somewhat trapezoidal bed.

The other job I finished is the building of a frame to use to hold up my raspberry canes. For the frame, I used four 1-by-2 boards with a pointed bottom, and four 2-by-2 boards for cross-beams. I will be adding eight hooks and then running wires between them. The idea is to create two channels of wire through which the raspberry canes will grow. The frame is supposed to improve air circulation and make the raspberries easier to pick by keeping them at eye-level. When I was installing the frame on the raspberry bed, I noticed that the raspberry canes left standing over the winter had buds on them. With any luck, there will be a July crop of berries, as well as the early fall crop that we had last year.