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Planning the planting layout of a high tunnel

High tunnel gardenWith fall in the air, season extension is now a hot topic. One of the most effective ways of getting a few more harvests in is with a high tunnel. Whether you’re considering purchasing a high tunnel or you already have one installed, there are a few guidelines for the layout of your high tunnel that you should consider in order to achieve maximum production. In this blog, we will discuss some of the major interior layout factors that you should consider when preparing to grow inside a high tunnel.

Planning your growing space

After completing the final step of installing the structure, many people assume that the construction is over. However, it is only after the high tunnel is upright and covered that the real construction begins. Many people think that with a high tunnel, the entire space is available for crop production. While this is true in many ways, there is a certain respect that needs to be given to the floor space of a high tunnel in order to create an ideal environment.

High Tunnel FramePlanting layout

As an example of ideal layout within a high tunnel, we will base our layout off of a 20’W x 72’L Economy Round Style High Tunnel. With a structure this size, there is a total of 1,440 sq. ft. of growing space. However, not all of that space is available for production. In fact, approximately 30% of that should be devoted to walkways and other working space, so the useable space is really only about 1,008 sq. ft.  overall. This is why many find it beneficial to plan the interior design of the high tunnel prior to purchasing a structure.  This way you can purchase a high tunnel large enough to produce all your desired crops, rather than having to choose certain ones because the growing area is smaller than anticipated.

Many that have grown in a high tunnel have found that in general, a layout of 30” wide beds with 12” walkways is the most efficient way to design your high tunnel. This design allows for plenty of room to plant seeds and it leaves enough space to safely pass between the rows of crops. There should also be a cleared space at either end of the high tunnel, so that you can enter without risk of damaging your crops. This space can be used for storing tools or as a work area for any additional chores that may arise. Usually about 2’ is enough space for an entryway. If you plan on entering the high tunnel from both ends, you should consider leaving 2’ of space on both ends. By following this layout within a 20’W x 72’L Economy Round Style High Tunnel, you would have six, 68-foot long planting beds with five walking paths among them.

Design of high tunnel planting

Basic blueprint of a high tunnel layout

Creating the area

Once you have planned the layout for your high tunnel, it’s time to put your design into effect. We recommend using the following materials: a tape measure, wooden stakes, hammer or mallet, twine or string, a shovel and a rake.

  • Measure out the 2’ entryway on one end of the structure.
  • After finding the 2’ mark, spread the tape measure horizontally and mark the width of your planting beds by driving a wooden stake into the ground at your pre-determined starting and ending points. (Following our example this would start at 0” and end at 30”)
  • Continue to drive wooden stakes into the ground to designate the width of all planting beds.
  • Upon completion of the front side of the structure, move to the back side of the high tunnel and repeat the same process.
  • Once all planting beds are marked, take the twine or string and tie it around your first wooden stake.
  • From your starting stake, walk in a straight line along the length of the structure until you reach the farthest stake.

Visualizing planting beds

  • From here, wrap the slack of the string around the stake and bring the remaining string to the next wooden stake. Wrap the strings slack around this.
  • Walk back down the length of the structure until you reach the only unmarked stake in your first planting bed. Wrap the ropes slack around the remaining stake and extend to the wooden stake you started with.
  • Cut and tie off the string around the same stake that you began with. This marks the area of your first planting bed.
  • Repeat this process for the remaining planting beds.
Small scale finished string grid in garden

Small scale completed string grid in garden

  • Once all beds are outlined with string, you can now see where the walkways will be, if you discover any spacing issues at this point, you can correct them before any major work has been done.
  • You can now dig the pathways. This is recommended because a lowered pathway has proven easier to work in and it clearly designates all pathways.
  • Take the dirt that is being removed to create the pathways and place it in the planting beds. This reduces the need to exert energy removing the dirt and also reduces or eliminates the need for additional dirt if you are looking to raise the planting beds.
  • Once all pathways have been created, you can remove the stakes and string and tend to your planting beds as necessary. You can remove rocks and other unwanted material and add mulch, lime or other growing media as needed.

Offseason care

High tunnel in winter

High tunnels provide an extended growing season, but with crop production still being in-ground or in raised beds, in most regions your growing season will eventually come to an end. Even if you do grow year round, it’s a good idea to allow for a fallow period. Once your final crops of the season have been harvested, be sure to winterize your growing area as usual. Remove any insect or disease infested crops, turn the soil and add mulch and fertilizer in preparation for next season’s growing. Leaving your cover on over the winter months is acceptable however, if you choose to do so, you will need to be sure to water thoroughly next year before planting. With the cover left on, the soil inside the high tunnel will not receive the natural hydration from rain and snow fall, and if you neglect to water generously prior to planting next year, the soil will be too dry to support a healthy crop yield.

Growing within a high tunnel is an excellent way to enjoy the experience of gardening outdoors all while modifying your environment and extending your growing season. With proper planning ahead of time, transitioning to high tunnel crop production can be quite painless and the difference a high tunnel has on your crop yield makes the investment well worth it. Consider the planning tips discussed and if you have any additional questions, leave us a comment; we want to help you get the best harvest possible out of your high tunnel.

Ideal high tunnel layout

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