Tuesday, March 29, 2016

Grow more earlier (and later) with a hoop house

The local newspaper recently ran a gardening column about building hoop houses, so I reached back into the archives and found this article I wrote about a speaker at a Small Farm Conference in Columbia nearly 15 years ago. It still has some good information, I think.

An Iowa market grower looking to lengthen the short growing season up North has come up with a low-cost idea that Ozarks gardeners can use, too.

“You get better prices the earlier you can get (produce) to the farmers market and the later (in the season) you can stay,” says Doug Webster, of Rolling Prairie Acres, Sigourney, Iowa. The question he asked himself was this: How can a market grower, whose livelihood depends on how much he can pull out of the ground for his customers, start harvesting greens earlier in the season and keep picking tomatoes later?
The answer; “Build low-cost hoops from hog and cattle panels,” Webster said.
By hoops, he means hoop houses, which are unheated greenhouse-like structures built in the shape of a Quonset hut with a skin of greenhouse film covering the arches.
These hoop houses can be built from various materials of various costs, but a market grower like Webster is looking to find an inexpensive way to put up a hoop house. Ozarks gardeners will concur with that goal.
“We’re trying to keep our costs low,” Webster said, explaining that he and his family grow 65 vegetable crops on 2.5 acres of the 10-acre farm. They also raise Katahdin sheep, turkeys, chickens and rabbits.
They sell their produce at a large farmers market at Fairfield, Iowa, and to 30 members of their CSA (Community Supported Agriculture) program. Their customers want spinach, lettuce and greens early in the season, but Iowa’s weather isn’t conducive to early harvests.
“We’re 190 miles north of here,” he said.
Rolling Prairie Acres has two wood-heated greenhouses, but those structures don’t provide enough room to get a head start on the produce for those customers. Building another wood-heated greenhouse is expensive.
That’s why Webster likes his hoop house design made from the animal corral panels.
“ I like 16-foot hog panels, because they’ve got more steel in them, so they’re stiffer,” he says. “A 16-foot panel can be arched to give you 8 feet in width and 6 feet of head room, and I can stand up in one of these.”
Moreover, in Iowa, so many hog farmers have left the business in recent years, that he has been able to find an ample supply of hog panels at no cost.
The lengths of the hoop houses can vary. Webster built a 22.5-foot long hoop house in 2004 using eight 34-inch panels. He used 12 54-inch panels to build a 54-foot long hoop house in 2005. This year he built another 22.5 foot house.
Has it helped? Weber says it has, noting that he has over-wintered spinach and can harvest in March. He has planted tomatoes the first week of April and harvest the first one on May 31. At the November 2-4 conference, he said he had eaten fresh tomatoes (in Iowa) just that previous week, thanks to his hoop houses.
He plans to build another 22.5-foot house in 2007 to use for growing strawberries.
To build a hoop house, you’ll need corral panels, 2x4 lumber for the base frame, 1x3 lumber to fasten the plastic, deck screws, fencing staples, cable ties (black, UV protected) and 6 mil greenhouse film.
Webster gives the following steps of construction:
  1. Build a base frame of 2x4’s; make it as a long as you want. Drive a pipe into the ground and fasten it to the frame to hold it during high winds.
  2. Bend panels and staple them to the frame. This will take two people. Fasten each panel end to end with a cable tie.
  3. Build door frames on each end and install them.
  4. Fasten film on one side of a door frame on one end; stretch over the length of the arch and fasten to the door frame on the other end with 1x3 lumber. Use 1/3 on the length of film next to the base frame, too. It helps to have 8 arms on this step.
  5. Install the film on the doors, using scraps from the ends.
  6. Build and install flat shelves for plants if wanted. The frames for these flat shelves can be made with 3-foot lengths of 2x4’s attached at one end to the side of the hoop and on the other end to a length of No. 9 wire hanging from near the top of the hoop.
Webster noted that by putting up shelves, you can grow plants in the ground and in flats on the shelves.
He cautioned that long hoop houses can be difficult to ventilate. He added a fan to the 54-foot hoop. He opens the doors on the shorter hoops.
Houses longer than 22.5 feet need supports every 16 feet on the base frame.
Webster also cautioned that you should use 6 mil greenhouse film, not 6 mil plastic.
He also said non-treated lumber should be used so no chemicals leach into the soil.
“Place straw bales around the base during winter to help with keeping the ground warmer,” he said.

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