Yesterday I attended a webinar on hoop house construction that was presented by the National Sustainable Agriculture Information Service. There were 600 on-line participants with 450 still tuned in at the end of the webinar. Tammy Hinman and Andy Pressman were the speakers.
The focus of the webinar was extending the growing season for farmers to give them a head start on getting their produce to market, but the principles can be applied to even backyard gardeners. The full webinar will be available in a few days on their website, but I’ll hit the highlights.
- Hoop houses are used to give you an earlier start on the growing season, a longer harvest, and can even be used to grow through the winter.
- Yields are typically larger in a hoop house.
- You can have heat gains of 4 to 12 degrees.
- Hoop houses are generally not heated.
- A width to length ratio of 1 to 2 will achieve highest solar gain.’
- A narrow tunnel tends to lose less heat.
- Taller tunnels have better ventilation.
- Two days earlier in the ground equals one day earlier harvest.
- Beneficial insects aren’t prone to go into the houses, so you should introduce them.
- Shade cloth can lower temperature.
- Using a low tunnel within a high tunnel can make a difference equal to two zones south
- For winter success you should start your crops while the days are still long.
Types of Hoop Houses
- Low tunnel: inexpensive, easy to install but labor intensive
- High tunnel: high enough to stand up in. Can be semi-permanent, permanent, movable.
There are two basic shapes: quantic (rounded roof, sloped sides) or gothic (high pointed peak).
- Foundation needs to be firm.
- Soil should be well drained.
- You should have full sun and protection from winter elements.
- Orientation is specific to location, but north of 40 degrees latitude should be oriented east to west.
- Construction begins with ground posts.
- Frame can be made from wood, pvc, electric conduit, galvanized steel.
- Pulins run horizontal and helps stabilize the structure.
- Baseboard sits on ground and it’s where the plastic is attached.
- Hip boards run along sides a few feet off ground.
- End walls are constructed separately.
- Greenhouse poly film is a better choice.
- 4ml or 5 ml plastics can be used.
- Make sure plastic is applied tight enough to not cause flapping.
- Roll up sides, which allow access, are made using the hip board.
- Avoid soil salinazation – (I was sleeping a little on this one. I think it has to do with the condensation causing salt buildup in the soil).
- Add nutrients (compost at a ratio of 5 gallons for every 40 sq ft).
- Typical crops are lettuce, tomatoes, cucumbers, specialty flowers.
- You can do succession planting. For example, lettuce and greens then tomatoes and melons followed by strawberries in the fall.
- Your bed systems can be raised beds, permanent beds or annual beds.
- Containers such as grow bags and buckets can be used for quick turnaround.
Here are a few more highlights:
- Plastic can be used for weed management and warming the soil.
- Drip irrigation can be used and is especially good for longer season crops.
- For weed management, hand weed or mulch, although hay is not recommended as a mulch.
- There is usually a lower incidence of disease, and proper air ventilation is important. One form of management is to open structure in winter to allow spores to be killed.
- Common pests are aphids, mites and white fly. They recommend using biorational controls.
If you have question or want more info, you can visit the site (there are 300 publications available for download) or contact the speakers:
or call their help line @ 1 (800) ASK-NCAT
After the presentation, questions were fielded. Here’s a condensed version of the questions and answers:
Q: In a high elevation with a three-month growing season, should a high tunnel be considered?
A: Yes, because in the west you may have inclement weather, but the sun shines 300 days a year which will help with the solar gain which will help the warm season crops.
Q: Any info on Elliot Coleman’s quick hoops concepts?
Answer: Elliot is a Maine grower and author. He wrote The Winter Harvest. He pioneered the use of low tunnels. He uses low tunnels in high tunnels. He also wrote The New Organic Grower, the Four Season Harvest.
Q: Any info on kits and design sources?
A: Look locally to avoid high shipping cost. Haygove has an American supplier. Farmtech is a supplier that also has roll-up and roll-down sides. Farmers can also be suppliers.
Q: Can gray or black window screen be used as shade cloth?
A: May work, not familiar with using it. May not provide the needed protection.
Q: Any help with wind issues?
A: Wind is top issue with setting up house. Many plastic coverings are lost due to wind. One option is take it down during windy months.
Q: How to attach plastic in high wind area?
A: Depends on structure. Use heavier plastic, 4-6 mil. Can use grommets. Can use sand bags. Attach to hip and base board for security. Roll-up and roll-down sides help with wind issue.
Q: Anyone use carpet mulch in commercial setting?
A: Haven’t heard of it being used commercially, but be careful with glue in carpet. Can cause soil toxicity issues.
Q: Regarding companion planting, what kind of flowers to plant to attract beneficials?
A: Farmscaping to Enhance Biological Controlsis available as publication at ATTRA. Typical plants that attract beneficials are umbels such as flowering dill, fennel, yarrow, and nectar type of flowers. Most flowers will attract beneficials.
Q: Are there issues to be aware of as far as crop rotation?
A: It is important to prevent disease and insect build-up. If you can only have one hoop house on a farm, a movable type is good for crop rotation. For smaller growers, you can rotate within the house to help more with disease but not so much with insects.
Q: Any suggestions for season extension for warm season crops?
A: Not seen situation where crops are direct seeded. It may be possible further south. Often times what’s seen is plants started ahead of time. Hoop house may increase soil temp a little, only 4 to 10 degrees. Plastic mulch will help warm the soil to 60-70 which is what warm season crops like. As season progresses and it gets hotter, shade cloth can be helpful.
Andy has directed seeded in northeast with success with spinach, chard, kale. When the temps were negative 20 outside it was 15 degrees inside. If crops freeze, once they thaw they’re fine. Shade cloth can benefit southern growers.
That, in a nutshell, is the contents of the webinar. They plan on having two or three more this year.
As I said earlier, even though the presentation was aimed at farmers, the concepts can be scaled down for use by the backyard gardener. And remember, about 45 minutes of the presention will be available to be listened to in a few days at ATTRA’s website.