Greenhouse Plastic

The quick answer is ten to fifteen feet should be between each tunnel. However, below are some variables to consider when planning ahead on how to space your tunnels, especially if you want to set them up closer than the recommended spacing. 

Shadows cast from one tunnel to the next can reduce sunlight available for plant growth. This can be mitigated if the tunnels have a north-south orientation. However, if your growing context requires an east-west orientation (which is generally preferred), the lay of the land and the angle of the sun will need to be taken into consideration. Spacing between tunnels in relation to the sun is a concern due to shadows cast by the neighboring tunnel. This is more or less important in light of the growing season and crop selection. Ideally, tunnels are in an east to west orientation for solar gain. However, multiple variables must be considered. 

Snow also needs to be a thought for winter growers deciding how close their tunnels can be. When snow slides off the side of the tunnel it will build up on the tunnel walls. If the tunnels are too close, they will form a ditch-like-pocket where snow will collect. The distance between is relative to the amount of snow in a typical year. The greater amounts of snow, the greater the distance needs to be. Any snow that is removed has nowhere else to go. Depending on snowfall amounts and machinery size, one should count on at least 8-15 feet between tunnels so they can remove the snow from the side. You may find this article on snow useful as well. 

Rain is an additional variable to take into account, as the tunnels create a watershed. Thus causing issues with flooding or seed erosion for direct-seeded crops on outer rows. Soil type, lay of the land, and the typical rain intensity will play a role in this decision. With soils that absorb water better and areas that have less intense rain, the tunnels can be placed closer together.  Additionally, growing a cover crop in-between will help with water absorption and weed management in situations where they are closer than 30-inches or less.

Orientation (N-S, E-W) in relation to the lay of the land is something else to think about. Typically, we recommend tunnels follow the lay of the land lengthwise. In other words, like the caterpillar is inching up the slant, not across the slant. 

Wind passing over and around structures can create a wind tunnel effect. This can increase winds well in excess of the actual wind speed. Spacing out tunnels or creating windscreens can help with this. 

Spacing between tunnels depends on local weather context and tunnel orientation. Generally speaking, tunnels should be at least a tunnels height away or 8-10 feet, but 10-15 feet is ideal. However, they can be closer. 

Yes. However, below are some variables to consider, and caution with prudent planning is highly encouraged. These are only our guidelines and not a guarantee. 

Tunnel Orientation

You can install the tunnel perpendicular or parallel to the hillside. It is not recommended to trellis on an installation that is parallel to the hillside with a grade that exceeds three percent. This is due to gravitational pull from the weight of trellised plants on the bottom end of the tunnel. 

With an installation that is perpendicular to the hillside, one could install a basic tunnel with no trellising on up to twenty-five percent grades. 

Prevailing Winds

As far as prevailing winds, an installation of the tunnel parallel to the wind is best. The tunnel will more naturally shed the wind. In a perpendicular installation, in reference to the wind, the side plastic will have a tendency to catch wind and lift. 

This is exacerbated when the tunnel is on a hillside with prevailing winds whipping down the hill side. In this situation, one could still install a tunnel, however, it is recommended to seal off the uphill windward edge by burying the plastic. This will help prevent erosion and water shed inside of the tunnel as well.  See attachment. 

Land Grade

We do not recommend exceeding a twenty-five percent land grade (For Caterpillar tunnels), and no more than 3% (for Guardian and Haven High Tunnels, due to roll up sides and baseboards needing to be very level).  How do you determine your land grade? All you need is a 50” board, level, tape measure, note-taking device. Watch this video to see these tools in action. 

Erosion

The cardinal issue of growing on a hillside is erosion. Contoured rows, terracing, ditching, and raised beds are ways to mitigate erosion. In planning, the grower can incorporate tunnels into their hillside growing. 

In order to execute this, depending on the grade, you will need to cut the lift kit on the high side to compensate for the grade, or remove the lift kit from the high side and combine it with the low side after cutting it to the appropriate length. 

The Caterpillar tunnels are shipped on a 4x8 wooden pallet via motor freight (an 18 wheel tractor trailer). Depending on the order, sometimes multiple tunnels can fit on one pallet. Below is an example of what a past shipment looked like. 

Delivery Time

You will receive a pro number for tracking from Farmers Friend when your shipment is picked up from our facility. It is recommended that you contact the carrier prior to delivery to make arrangements for time and date. There is some flexibility in date and time of delivery, but customers in remote areas should accept delivery at the carriers convenience to avoid excessive delays or extra charges. 

Change of Shipping Address

If a change of shipping address needs to be made before your order is picked up from our facility, no problem. However, if this change is made after your order is picked up from Farmers Friend, there will be a reconsignment fee which generally ranges from $50-$150. Charges are determined by the carrier. 

Verifying Contents

Prior to moving or unloading, please take pictures of the order. This is in case items are missing or damaged we have a way to verify contents and condition. We recommend conducting an inventory of the shipment with your included packing list as soon as possible after unloading.

Unloading

Prior to mov­ing or unload­ing, please take pic­tures of the order. This is in case items are miss­ing or dam­aged we have a way to ver­i­fy con­tents and con­di­tion. We rec­om­mend con­duct­ing an inven­to­ry of the ship­ment with your includ­ed pack­ing list as soon as pos­si­ble after unloading.

As far as unload­ing, it is the cus­tomer’s respon­si­bil­i­ty. The car­ri­er will not have a fork­lift to unload. A fork­lift or trac­tor with forks is not required, as the ship­ment can be unloaded by hand with two peo­ple. Simply break the bands and remove the pack­ag­ing. The indi­vid­u­als unload­ing should be capa­ble of team-lift­ing 130 pounds. Out of con­sid­er­a­tion for the car­ri­er, we request you pre­pare to unload as quick­ly as possible.

Farmers Friend will not autho­rize the use of any lift­ gate ser­vices, and they are not includ­ed in any ship­ping charges, nor is it includ­ed with free ship­ping. If the local ter­mi­nal or dri­ver offers lift gate ser­vices, do not accept them for any rea­son as there will be an addi­tion­al charge billed to you from Farmers Friend at $150.

Each pallet will not exceed 2500 pounds. Below are some estimated example weights:

(This is only an example and not your actual order)

• 4x8 Pallet            100 lbs
• 50' Tunnel Kit     350 lbs
• 100' Tunnel Kit   625 lbs
• 24' Silage Tarp    61 lbs
• 32' Silage Tarp    83 lbs
• 40' Silage Tarp    99 lbs
• 50' Silage Tarp    124 lbs

Some carriers have lift gates, but there is a charge associated with its use. If you want lift gate, please let Farmers Friend know before purchase if possible. Lift gate services are not included in any shipping charges, nor is it included with free shipping. Lift gate service charges generally range from $50-$200 depending on the carrier. R and L is the only exception—they have free lift gate but their standard service rates are higher. Charges are determined by the carrier. 

If the driver offers lift gate services on site and you have not paid for them in advance, please do not accept as there will be an additional charge billed to you from Farmers Friend. 

Damage

In the event of your shipment being visibly damaged, we recommend both the driver and you taking pictures. The driver should also note the damage on the Bill of Lading (BOL) and you should send pictures to Farmers Friend. If the damage is excessive (obvious multiple items missing/damaged, pallet has been re-packaged) please refuse the shipment and contact Farmers Friend. We will arrange for a replacement order to be shipped via a different carrier. If there are only a few items damaged/missing, please accept the shipment and Farmers Friend will gladly make arrangements for quick replacement. 

As always, if you have questions or concerns, please contact Farmers Friend Customer Service at 931-583-0397 or support@farmersfriendllc.com. 

 

The forecast for wind or snowstorms can give rise to anxiety for many farmers. How do you best prepare for these events? The tips below can assist you in reducing the chance of sustaining damage to your investment. As the elders say, “An ounce of prevention is worth a pound of cure.”

The wind is best prepared for by anchoring, bracing, breaks, orientation, and sealing. In anticipation of a forecasted wind event, loose items should be secured or stowed. Additionally, all hardware and rope or strapping should be inspected to ensure tightness and serviceability.

Anchoring. The most desirable anchoring for tunnels in sustained high wind contexts is either cement or ground anchors. Ideally, ground posts should be anchored on the corners and every other bow. The bows which are not anchored should be driven at least two feet deep. Traditional caterpillar tunnels with rebar should be secured using ground anchors in high wind contexts (see Fig. 1). 

     

Bracing. Appropriate bracing for high wind includes wind or end wall bracing at each corner and a solid ridge purlin (see Fig. 2a and 2b). Wind bracing and purlin prevents racking of the tunnel from end to end. A lower profile tunnel is better in high winds. The lower profile is one advantage of caterpillar tunnels. 

Breaks. Sustained high winds are the greatest danger to your tunnel. This does not negate the potential risk associated with gusting winds. One way to mitigate both types is by installing windbreaks if natural ones like trees are not present (see Fig. 3). Windbreaks can slow down the wind and offer a protected distance zone ten times its height.

Orientation. Understanding the wind pattern of your farm is important when choosing the orientation of your tunnel. Prevailing winds can be an indicator of how the tunnel should be positioned. However, wind can be unpredictable and orientation rendered useless. The ideal orientation is with the narrow end facing the prevailing wind. This makes the best use of anchoring and bracing while presenting a smaller profile for the wind to catch. 

Sealing. Once you are in an actual wind event all openings should be closed. The side curtains should be dropped and secured with sandbags. If doors have been installed on the ends they should be closed and latched. If the ends are left open for summer ventilation a windbreak should be installed. 

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References

Bartok, J. W. (2018, August). Prepare your greenhouse for high winds. Retrieved October 17, 2019, from https://www.greenhousemag.com/article/tech-solutions-prepare-your-greenhouse-for-high-winds/.

Fortier, J.-M. (2014). The market gardener: A successful grower's handbook for small-scale organic farming. New Society Publishers.

Sparks, B. (2016, February 17). Tips to help reduce wind and snow damage at your greenhouse. Retrieved October 17, 2019, from https://www.greenhousegrower.com/technology/tips-to-help-reduce-wind-and-snow-damage-at-your-greenhouse/.

The forecast for wind or snowstorms can give rise to anxiety for many farmers. How do you best prepare for these events? The tips below can assist you in reducing the chance of sustaining damage to your investment. As the elders say, “An ounce of prevention is worth a pound of cure.”

Snow and ice are best dealt with by shape, bracing, spacing, removal, and preparation. In anticipation of a forecasted windy winter event, loose items should be secured or stowed. Additionally, all hardware and rope or strapping should be inspected to ensure tightness and serviceability.

Shape. The best shape for shedding snow is a gothic peak. This is in comparison to a quonset or rounded peak. The steeper angle increases the chances of snow naturally sliding off, and makes it easier to remove the snow that does accumulate. This does not mean that the quonset peak cannot withstand snow loads. It just means that the snow is easier to remove. 

Bracing. Appropriate bracing for snow and ice includes wind or end wall bracing at each corner and a solid ridge purlin (see Fig. 2a and 2b). It is recommended that only one overhead purlin be used, as two purlins create a holding pocket for snow. This increases the weight and likelihood of tunnel collapse or plastic damage. Wind bracing and purlin prevents racking of the tunnel from end to end.

Additionally, if a serious snowstorm is forecasted, one might consider shoring up the tunnel with notched 2x4’s that have 8inch x 8inch feet. For gothic peaks, this bracing should be wedged under the end of truss supports or under the ridge purlin. For quonset peaks, the bracing should be wedged under the purlin or in the center of the bow. It is recommended to place these every other bow or every fourth bow.

                

Spacing. The NRCS high tunnel initiative CODE 325 recommends that a minimum of ten feet or a recommended twenty feet around the tunnel be clear of obstructions. This is to allow space for snow removal equipment and room for the snow which is removed from the sides of the tunnel. The uneven pressures created by snow buildup on the sides unevenly because of neighboring obstructions or uneven removal from each side is a common reason for tunnel collapse. 

The spacing between neighboring obstructions or tunnels is not the only span to be concerned with. Decreasing the space between each bow (also known as rib or arch) is one way to increase the high tunnel strength. Generally, in areas with snow events, the bows should be spaced four feet apart. 

Removal. The weakest part of the tunnel from end to end is in the middle. This is because there are no end wall braces or anchoring. High tunnels are most stable when there is an even amount of snow build up on each side. Before removing the snow from the top of the tunnel, you should remove it from the sides by shoveling or using a snowblower. 

Snow and ice can be removed from inside the tunnel by bumping the bows or pushing up the plastic. This can be accomplished with a soft bristle broom or a long handle with a tennis ball on the end. Start at the bottom and work your way up. If you start at the top, the snow will have nowhere to go. Doing this from inside the tunnel is preferred as you can alternate from one side to the other easily. 

Sometimes snow cannot be removed from the inside. To remove snow from the outside, tie knots in a rope every couple of feet. Toss the rope over the tunnel and with another person, drag the rope back and forth using the same principles mentioned above. 

Preparation. You will find it prudent to keep a few items on hand. The lumber for bracing to shore up, soft bristle brooms or long handle with a tennis ball, back up poly for covering or patching, and greenhouse repair tape. Also, servicing snow blowing equipment in advance is wise.

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References

Growing for Market. (2011, January 20). How to get snow off a hoop house. Retrieved October 25, 2019, from https://www.growingformarket.com/articles/snow-off-hoophouse.

Grubinger, V. (2014, December). Prevent greenhouse collapse. Retrieved October 24, 2019, from https://www.uvm.edu/vtvegandberry/factsheets/PreventGreenhouseCollapse.html.

Lemieux, A. (2011, March 15). Johnny's winter caterpillar tunnel structural trial. Retrieved October 21, 2019, from http://johnnystooldude.blogspot.com/2011/03/winter-caterpillar-tunnel-structural.html.

Natural Resources Conservation Service. (2018, October). High tunnel general specifications. Retrieved October 24, 2019, from https://efotg.sc.egov.usda.gov/references/public/AK/AK_325_High_Tunnel_General_Specifications_Oct2018.pdf.

Poling, B. (2016, January 22). Managing snow and ice with greenhouses and high tunnels. Retrieved October 25, 2019, from https://strawberries.ces.ncsu.edu/2016/01/managing-snow-and-ice-with-high-tunnels-12216/.

Rose of Sharon Homestead. (2019, February 12). High tunnel/greenhouse snow removal & vlog. Retrieved October 25, 2019, from https://www.youtube.com/watch?v=OG82-JokjrU.

Sparks, B. (2016, February 17). Tips to help reduce wind and snow damage at your greenhouse. Retrieved October 17, 2019, from https://www.greenhousegrower.com/technology/tips-to-help-reduce-wind-and-snow-damage-at-your-greenhouse/.

From time to time customers ask about tunnel maintenance in the winter when it is not being used for growing.  This is a great question and the short answer is "it depends on your location and how much you want to work."  Let's explain...

LEAVING THE TUNNEL UP

There are several reasons why leaving a growing tunnel up for the winter could be to your advantage.  The main reason has to do with weather.  If you live in an area that receives a significant amount of snow then leaving your tunnel up allows you to keep the ground relatively prepared for spring seeding and/or planting.  Covered ground is usually not too wet and muddy in spring, requiring less work for  planting.  Because of the shape of the tunnel (usually quonset, rounded) snow does not usually build up excessively since it slides to either side.  If you do leave your growing tunnel up for the winter you also need to winterize the water lines by disconnecting the water source and opening the ends of your irrigation lines to prevent the water from freezing and cracking your lines.  Disconnecting a flush valve, filter and/ or any electronics (like a timer) and storing them inside would also be beneficial to prolong their life.  On the other hand, of you live in a warmer climate that gets little to no snow leaving your tunnel up may work perfectly into your growing strategy as well as not require much extra work.

TAKING YOUR TUNNEL DOWN

If you decide to take your tunnel down for the winter you will incur a little more work, but it may be to your advantage.  The biggest reason to take your plastic off and winterize your water lines would be to prolong the life of your plastic.  By taking the plastic down and storing it inside you remove the weather factor (especially the sun) from deteriorating the plastic and add life to it.  It may be possible to add several more growing seasons by removing the plastic, winterizing the watering lines and storing the flush valve, filter and any electronics.

The down side to removing the plastic, besides the work, would be the shape of the ground when planting season returns.  Again, if you live in a place of significant snow your tunnel may be full of snow in April or even May when you might be ready to plant your cool weather vegetables.  Instead of being covered all winter and ready to plant in spring you now need to clear the snow from your beds which will cause a muddy mess, let it dry and then prepare your beds for planting.  On the other hand, if you live in a warmer climate that does not receive much, if any, snow taking your tunnel down might be a great way to preserve your plastic and increase your investment.

At the end of the day either decision is fine and depends on the amount of work you want to do and the place where you live.  Whether you take your tunnel down or leave it up it would still be good practice to clear your water lines and store any valves, filters or electronics.  Those are relatively easy to detach and reattach when ready.  Happy growing!

See also this video from Curtis Stone from Canada and the amount of snow he sees.