Low tunnels don't seem to make sense?

veggievicki(7b)February 12, 2013

I put up a 4x20 low tunnel about a month ago, just so I could get something up and running. But the more research I've done, it just doesn't seem to make economic sense to bother with them, except maybe insect control. I've read a few studies on line, university type studies, not anecdotal personal experience stuff (not that those are not valid as well), and indicators are the low tunnel only gives you maybe three degrees of protection and very little increase in yields. Cost wise, I'm going to use a ten foot section on the low tunnel. Two ten foot sections will give me an eight foot high tunnel, which, if you believe the research, is going to give me more like seven or eight degrees of heat gain and significant increase in crop production. I guess the end walls are the big leap in switching to high tunnels?

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It depends on what you need, for me, I would need more early and late heat. Where you are at you should need as much.

    Bookmark   February 12, 2013 at 2:34PM
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little_minnie(zone 4a)

When you say low tunnels do you mean just wire hoops with row cover or Eliot Coleman's EMT low tunnels? He still uses many so I guess they must work.

The ones I am making this year will be mobile by taking apart and moving as the season goes. They will look a little like the one in the link only 50 feet long and instead of a raised bed they will be stuck onto rebar sticking out of the ground.

As for hoops with row cover, I had many beds this fall covered with wire hoops and 2 or 3 row covers on top. They brought cold hardy veg through much of December until it snowed deeply. That was sure worth it!

nice pic

Here is a link that might be useful: a pic of a homemade low tunnel

    Bookmark   February 12, 2013 at 6:40PM
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My question wasn't whether they work but whether they make economical sense. If you're only going to cover a couple Of raised beds, yes. But if you're covering more maybe not. I could cover a four by twenty four bed with one pipe per hoop or I could cover an eight by twenty four with two hoops and get a lot more protection and harvest. Us I can still use low tunnels inside the high tunnel. In the spring for me there's always that one night where the temPs plunge and the low tunnel just isn't enough. I've had better luck in the fall with Established plants.

    Bookmark   February 12, 2013 at 8:08PM
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The busiest vendor at my market in May is the guy who sells early strawberries, produced under row covers.

    Bookmark   February 12, 2013 at 9:28PM
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If you can be the first of anything, then YES they make sense. They don't have to be expensive, I've bought some smaller ones for less than $10 and it doesn't take long for get that back. If you can get $1 more for just 1 week, all you have to see is 10 lbs.

I have kept mine for a few years. After I don't need them, I gather them, fold them up and store them in a darker room. The thinner the more light and I found that they are more delicate. For those that keep the in the fields for weeks, they may not be able to re-use them for as long.

    Bookmark   February 14, 2013 at 8:53AM
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I use low tunnels (row cover on #9 wire hoops) on about 3/4 of my market garden. Do they make economic sense? Yes they do for a lot of crops. They do no make sense for trying to start seeds in January anywhere but the Gulf Coast but they are great for protecting hearty greens like kale and collards from cold weather and wind (which is what does most of the damage, not the cold).

they are great for starting direct planted seeds. We use the flat on the ground to keep the soil evenly moist and to stop it from crusting over in heavy rains as well as keeping the seeds from floating away in said rains.

We use them to keep insects off the crops

We use them to keep wind, heavy rains and hail from ruining leafy green crops.

We use them to get really high quality arugula and lettuce

We use them inside of hoop houses to gain another planting zone

We use them to isolate plants we are saving seed from

We use them year round and probably go through 2500' each year (and that is with using the covers for at least 1.5 seasons, most go 2.5 seasons)

    Bookmark   February 14, 2013 at 11:13AM
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little_minnie(zone 4a)

Well are we talking about low tunnels, what Johnny's calls Quick Hoops, or are we talking about wire hoops? They are two different things and the area covered is quite different.

    Bookmark   February 14, 2013 at 11:44AM
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I can relate to what you are saying Vicki, I do live in a warmer climate though. I continue to use row covers and other climate modification stuff to better "be in the business" or try to be. I figure some plantings are lower profit but need to be grown to represent our farm better nonetheless. (trust me it's a work in progress).

The guy the colerobbie mentions, who is selling strawberries in May , may or may not be making much on them but he has built his customer base if he intends to keep selling as warm season crops come in.

Sometimes I do think, we should just do what's easy in the easy time of year, but our markets are year round even though growing/having much to harvest is a big challenge in some parts of the year.

The markets need us to do our best to maintain a quality experience for as many customers as possible. If we don't we have no place to sell.

I think this could apply to selling to restaurants or other outlets as well. Who does a good job for them matters.

    Bookmark   February 14, 2013 at 12:24PM
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i use wire hoops. they are cheap and easy. they don't handle snow/ice/hail very well. but we were harvesting spinach, pac choi, collards, chard, and arugula from under them until mid january or so, when we had that 10" snow storm.

    Bookmark   February 14, 2013 at 12:52PM
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I have a 6' X 100' low tunnel where is packed full of thousands of plants that I use to transplant later in my garden, or to sell as potted plants at farmers market ( I sell about $14,000 in plants a year). The thing which is MUST additionally have is an agribon frost cloth to cover over the whole thing when temperatures get into the upper 20's. It requires me to bend down a lot, but the whole thing works perfectly and was very cheap to purchase and to maintain. Low tunnels are also great to get a head start on any kind of garden plant which is planted directly into th soil, but yes, you must have a frost cloth on standby, because plastic doesn't hold much heat.

    Bookmark   March 16, 2013 at 8:26PM
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I was thinking more exclusively for heat. Not insect control or shading. It seems cost wise you can do a high tunnel for what the low tunnel costs because you exponentially cover more and you get considerably more protection. I suppose if the low tunnels do double duty, then that would increase their effectiveness.

    Bookmark   March 16, 2013 at 11:01PM
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For winter you really need high tunnels to do a lot of produce and be able to get that produce out of the fields. There are lots of problems with harvesting in snow using low tunnels; starting with how to get at the crops, than how to keep the crops from freezing (harvest into warm coolers) and how to get harvest lugs/coolers out to the field (we use a toboggan). Not to mention, comfort-it is usually cold wet and windy when harvesting in winter outside. With high tunnels you don't have to deal with most of these issues other than how to get produce back to the packing shed with no freezing through snow (cooler on a toboggan).

That said, row covers in high tunnels are a very good thing as it gives a lot of extra protection to the crops. But cost wise I can put up probably 20 low tunnels for every high tunnel. Though low tunnels cover 1 bed and high tunnels cover 4 beds. The high tunnels are home made as well and only cost about $900 to make. A commercial high tunnel would cost more like $5K and for 5K I can cover all 300+ beds on my farm for 10+ years with low tunnels

And realize low tunnels and high tunnels do very different things are are not meant to replace one another but rather complement one another.

    Bookmark   March 17, 2013 at 5:42AM
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little_minnie(zone 4a)

I am making 2 low tunnel/quick hoops to the dimensions I want. A guy from this website's forums who lives in MN (soilent green) has been helpful in bouncing ideas off and telling me they won't work.
My 2 tunnels will be 48 feet long each and the hoop part will be made with poly tubing 3/4 inch available locally for $60 for 400 feet. That will make about 32 hoops at 12.5 feet each which is a little more than needed. The tunnels will be covered with 14 foot row cover and 14 foot greenhouse film so that the film can be removed when it gets warmer but the row cover is there for cool nights. The hoops will be placed over rebar. This will be a decent expense. However, being I rent the land I cannot put in a high tunnel so I figure 2 low tunnels should work pretty well for me.
greenhouse film 14x110 delivered =$184.00
tubing 400 is a little more than needed but that is fine =$60
row cover 14x110= $40
shade cover 6x100 with grommets, I didn't get a final invoice on this I think it was =$200
sand bags 50 c each may use 50= $25
rebar 64 pieces 32 for each= around $85 -less if I cut long pieces when on sale
twine already have
EMT for spine 10x 10 ft long= $15.60
Clamps I haven't found the ones I should order yet= ?

The low tunnels will equal around $300 each. But the materials should last several seasons. I will admit it does seem high but that is how I have to do it. The tunnels will cover 2 beds each and have a path in middle. They will be moved from tender crops in April and May to cool season crops in summer and back to fall crops in mid September. I may reinforce the two into one tunnel and leave it up through winter depending on how they seem to hold up. I hope the early veggies, extended lettuce and brassicas, extended summer veggies and fall crops into December will pay for it.

    Bookmark   March 17, 2013 at 1:30PM
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I think that whether to use low or high would depend upon the area that you're in. Northern growers might need more protection, while southern (zone 6-7 or more) need less.

We need to keep in mind that what might work in AR/Tx might not work in MN/WI and vice versa.

    Bookmark   March 17, 2013 at 1:39PM
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Little minnie, I think you and I aren't using the same terminology. I think of a high tunnel as one you can walk in and a low tunnel as one that just covers a crop. The university studies I have been reading indicate that low tunnels don't do much more than frost protection. That the crops under low tunnels do not grow faster or more productively than without. I seem to be coming up with the same results. I planted 32 brocolli, two varities out with a low tunnel. Then a month later planted about 100 more without cover. I even left the cover on the 32 for a couple weeks after the others were planted. They are pretty much at the same stage now, and in fact the biggest ones are in the later planted bunch. Plus I didn't have the hassle of removing the plastic to water and fertilize.

    Bookmark   March 17, 2013 at 4:04PM
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The definition that is used for low tunnels, people can't stand up straight in them (of course, some people are shorter than others) and high tunnels are designed for people to walk/work inside of them.

Both high and low tunnels usually have drip tape installed to help with the watering.

    Bookmark   March 17, 2013 at 4:39PM
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little_minnie(zone 4a)

See link to explain what low tunnel is and how they work.

Here is a link that might be useful: eliot coleman's article

    Bookmark   March 19, 2013 at 10:53AM
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I'm wondering if they would help to get tomatoes, peppers, etc. out earlier, even if you have to uncover them later (and of course can't extend the season into the fall, at least not tomatoes, b/c they're too tall)?

    Bookmark   March 19, 2013 at 12:59PM
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little_minnie(zone 4a)

I will be using mine over tomatoes, peppers and melons planted one month early. I will use them over later planted tomatoes, basil and peppers in October and part of November and also some greens. In the middle they will be used to shade brassicas and greens.
Being spring here is the latest on record I think it will be very good I am making these.

    Bookmark   March 19, 2013 at 3:26PM
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Sheila, what Eliot does will probably work for you, since you are both in the same area. Some of his ideas doesn't work for me, I've tried. I've even went to one of his seminars and bought one of his 'updates' to one the books. $20 for 10 pages of paper, not worth it to me.

There are actual definitions of low and high tunnels per the USDA now, along with greenhouses versus high tunnels.

    Bookmark   March 19, 2013 at 3:27PM
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I can't read the whole thread but want to chime in anyway :). I agree with marla, Low tunnels work great dependiing on when and where you want to use them.

In my warmer sunnier climate they are season extenders for warm season crops, mostly start of season with other tricks like black plastic. I am going to try dwarf tomatoes in the fall under row cover and see where that gets me. Some cold season stuff grows better with the low hoops and row cover, but it's not really needed much.

A high tunnel could be good as a wind block for seedling starting transplant protection, but not that useful otherwise compared to low tunnels. low tunnels can cover flats of seedling just fine a lot of the time too. 20 miles away on the coast they can do passive hot house high tunnel tomatoes in the winter because nights are much more temperate.

    Bookmark   March 19, 2013 at 6:09PM
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little_minnie(zone 4a)

Arrrggghh! I have to majorly complain. So back some weeks ago I was checking out where to get all my needs in as few places as possible. Berry Hill had the plastic (4000 feet black and 4000 feet b&w) and drip tape and fittings but they would not sell me the amount of row cover I wanted. I wanted 15' wide for the low tunnels but 200' long. They were all snotty and said they would never cut so little. So I thought it was better to try elsewhere. I found a good deal at Robert Marvel on the plastic (4000 ft black and a better 2400ft w&b) and drip tape but they didn't have the right fittings and I needed just a few more for the year. They didn't have 15' wide row cover so I got the 7' they had and took it to the alterations shop to have 100 feet long sewn down the middle so I could make 2 50' tunnels. I didn't think it would cost that much and it saved me buying and shipping more row cover than I needed.
Guess how much they charged me?
I haven't even inspected their work yet.
So obviously I am pissed at myself for making stupid calls! I should have just bought all the stuff I needed from Berry Hill and gotten the shortest length of 15' wide they would sell me and the drip tape and plastic and fittings all there! So mad at myself and so much money has been spent it makes me neurotic. And yes it is another blizzard outside right now. I ordered the few tape fittings I needed to add footage from Dripworks. Fedco was way more expensive. I spent $48 total on that. What a bad season this is!!!

    Bookmark   April 22, 2013 at 8:10PM
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jrslick (North Central Kansas, Zone 5B)


I have learned the hard way too, just buy more than you need and you will use it, and it keeps really well!

Also, when you need extra(for a cold night) you will have it on hand.

For me, example tonight, cold and up to 3 inches of snow forecasted. We had two layers, we upped it to 4, only because we had it on hand.

    Bookmark   April 22, 2013 at 8:24PM
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We always buy row cover in 1000'+ rolls as it is cheaper (by a lot) than getting it cut to length and we use every bit of it. Nothing like a deer or other critter putting some big holes in your covers over night and not having anything to replace it with.

    Bookmark   April 23, 2013 at 5:52AM
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little_minnie(zone 4a)

I do have tons and tons already and nowhere to put it. I wanted brand new for this project but yes I wish I had just ordered from Berry Hill. The guy on the phone was a real jerk so I can put some blame on him to make myself feel better!

    Bookmark   April 23, 2013 at 3:40PM
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So did you get any spring crops in under the tunnels before the snow came?

    Bookmark   April 23, 2013 at 3:43PM
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little_minnie(zone 4a)

The tunnels are not built. They were supposed to be built the third week of April and planted on the 23 and 29th. The ground has been pretty frozen until recently and I have never seen ice on the lakes this late. My first day in the garden will be tomorrow but there are still snow patches.

    Bookmark   April 24, 2013 at 11:39PM
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