Protected Environment (High Tunnel) vs Non-Protected (outdoor) Yield and Growing Trial:

Overview - Trial Layout  -  Information we are asking you to record  -  What is considered Harvestable?  -  What is considered Waste?  -  What if plants die, get diseased, get eaten by animals, etc.  -  What do we do with all the produce we are growing?  -  Other High Tunnel Varieties  -  If you have never grown in a high tunnel before here are some things to consider


All growing supplies including seeds can be purchased with grant dollars.

Remember this is a trial to compare crop yields and growing in a high tunnel vs outdoors. To have the best comparisons keep everything as consistent as possible. Examples include:

  1. Recording produce weights from the same number of plants inside and outside.

  2. Pick produce when it is ready. Do not worry if you pick more times inside vrs outside. Just be sure that each time you harvest you record the date, weight, vegetable type, variety and if it was in the high tunnel or outside.

  3. IF you trellis inside the high tunnel then trellis outside as well.

  4. If you prune to a single stem inside the tunnel do the same outside.


Trial layout

  1. 10 foot row = 1 plot. with same number of plants in each plot.

    1. Tip: To achieve same number of plants start seeds in starter trays and transplant into the tunnel and outside.

  2. Plant at least two plots of the same variety, more if you want. This helps to verify data and if something happens to one plot you have a back-up so everything is not lost.

    1. Tip: leave space between each plot. As the plants grow if you are trellising it may seem like things start to get out or control. Space will make it easier to determine where one plot ends and the other starts.

  3. Plant required variety of:

    1. Corinto cucumbers

    2. King Arthur peppers

    3. Big Beef tomatoes.

  4. Plant another crop of your choice to compare growing.


Information we are asking you record:

We will be providing templates to help with data collection. We will also set up webforms for you to submit your information online. More to come in April.

  1. Planting and transplanting dates.

    1. Inside

    2. Outside

  2. Date of first harvestable produce

    1. Inside

    2. Outside

  3. Pounds of harvestable produce harvested every time, in each test plot, including the variety

    1. Inside date/pounds/variety

    2. Outside date/pounds/variety

    3. If this data is broken down by each harvest it will be good to compare yields over time.


What is considered Harvestable?

  • Good question. Ask yourself would you eat it or sell it at a farmers market?

  • If it looks ugly but shows no visible signs of disease or damage it is harvestable.

    • If you are noticing a lot of ugly produce, that would be good to note on the visual inspection sections.


  1. Pounds of Waste;
    1. Inside date/pounds/variety

    2. Outside date/pounds/variety

FOOD SAFETY BEST PRACTICE: DO NOT pick all the produce and sort it. Go through first pick the “harvestable” produce. Then go through and pick the waste in a separate container. The goal is to keep from contaminating the “harvestable” produce. (Contamination can occur from the produce touching or the person handling both types at the same time). If possible, this could also be accomplished by having sperate students pick the harvestable and the waste.


What is considered Waste?

    1. If you would not eat it, or sell it, it is waste.

    2. Produce that has fallen to the ground even if it looks good is waste.

    3. Produce that has fallen to the ground during picking is also waste.

    4. Example, If you have a tomato that has some end rot that whole tomato is waste. I understand that you may say, “I could cut that off and still make salsa with the rest.” Think of it this way if you were selling that tomato whole would you display it on your farmers market stand?

    5. Use your best judgement when picking waste. If it is really diseased, rotten or you do not feel comfortable touching it, do not handle it. This is especially true for produce that has fallen to the ground. Getting that weight is not worth jeopardizing your health or contaminating equipment.


  1. Visual observations
    1. This is not a must ever time but if you notice differences, we ask you document them. Some visual observations might include but not limited to:

      1. Size of produce harvested

      2. Quality of produce harvested

      3. Disease pressure

      4. Pest pressure

      5. Rate of plant growth

      6. Did you notice a difference in overall health of the plants inside vs outside?

      7. Others


  1. Flavor
    1. At some point we would like you to do a taste test and see if you can taste a difference in the vegetables grown inside vs outside.

  2. Date of last harvestable produce
    1. Inside

    2. Outside

  3. End of trial evaluation


What if the plants die, get diseased, get eaten by animals, etc. etc.

  • That is OK all research trials have their challenges. That is why they call it research.

  • One of the ways to mitigate that is by planting multiple plots of the same variety.

  • We ask that you record what you learned and any observations that you had along the way.

    • This is a great teaching opportunity for you as a teacher. People can learn just as much from failures if not more than from successes.

  • After I receive the data and information back from all the schools I am going to compile a final report to share the trial results from all the schools and observations. It is my hope that this document will contain a lot more information than the number of pounds of produce each plot produced.


What do we do with all the produce we are growing?

  • The produce cannot be sold!! This is a grant and generating income is not allowed.

  • Give it away. Do not feel bad taking some produce home and consuming it with your families.

  • Give it to the school meal program. Many schools have summer feeding programs. The fresh produce would be welcomed to put towards those feeding programs.

    • Fall school meals – Growing in the high tunnel I am hopeful that you will be able to grow fresh produce after it freezes. Work with your school to have it available at school lunch.

  • Donate to a food pantry, soup kitchen or senior center.

    • Fresh produce is not like a can of soup. Please make sure someone is available to receive the donation.

    • If you donate to a food pantry it would be good to also record that weight. At the end of the season to say you were able to donate this many pound to local food pantries is something you should feel proud of and worth talking about.

  • Exhibit at the local fair.

    • If a student has been working hard all summer on this project exhibiting at the fair would be a great way for that student to get acknowledged for a summer of hard work.



Other High Tunnel Varieties:

Below are suggestions of varieties that grow well in high tunnels from producers in North Dakota if you want to grow more.


  • Socrates Slicing

  • Excelsior – Pickling

Growing/variety selection tip:

  • For cucumbers I prune to a single stem and trellis up. I prefer to grow the seedless varieties bred for high greenhouse production, One reason I prefer greenhouse specific hybrids is they don’t require nearly as much pruning to keep under control as the older varieties do. They have much higher disease resistance as well. Parthenocarpic varieties produce seedless cucumbers. The seeds are barely noticeable but never develop. Gynecious only produce female flowers and these plants need less pruning in my experience..



  • Goliath

  • Red Knight

  • Gourmet

  • Carmen – Bull nosed

  • El Jefe Jalapeno

Growing/variety selection tip:

Seek out those varieties with fewer days to maturity.

The King Arthur variety will turn from green to red if given enough time. If you pick them early and they are still green they will still be good to eat. The peppers I have grown outside it can be challenging to get them to turn color. This will be interesting to see how this variety compares when grown inside vs outside.



  • Big Dena Slicing

  • Bella Rosa Slicing

  • Grenadero salsa/canning

  • Pink Tiger, Blush Tiger, Pink Bumblebee, and Sunrise Bumblebee cherry tomatoes

Growing/variety selection tip:

  • For tomatoes recommend only growing indeterminate types and keeping them pruned to a single stem and trellised. This helps with space, production and disease prevention. Hybrid tomatoes tend to have thicker skins and can be held on the plant to peak ripeness, whereas heirlooms tend to crack at the shoulders. If possible, seek out those that are bred for high tunnel or greenhouse production as they have more disease resistance. Look for cherry tomatoes that are crack resistant. Tomatoes crack much quicker in high tunnels especially if they have just been watered heavily. Try to keep the soil from drying too much between waterings to prevent blossom end rot.


If you have never grown in a high tunnel before here are some things to consider.

  1. Contact a grower in your area that has experience growing in a high tunnel and visit with them about the difference they have experienced.

    1. If you do not know of a grower contact me and I will help getting you in contact with a grower who can help

  2. Seeding and transplanting

    1. As mentioned earlier you may be planting in your high tunnel as early as the middle of May.

      1. It is very unlikely that a local nursery will have the tomatoes and peppers you need when you are ready to plant. I would recommend starting your tomatoes and peppers by the first week of April.

    2. Cucumbers

      1. Many growers will direct seed their cucumbers inside the tunnel. You have some options here:

        1. You could direct seed when the soil temps are above 50 degrees inside the tunnel and see what germinates. Then plant outside when you can see what germinates and thin the plots (remove plants) to make sure there are equal number of plants.

        2. You could start from seed in greenhouse or indoors about 2 weeks prior to an expected outside planting date and then transplant to get the exact number of plants you want in each plot.

  3. Planting Dates
    1. When should you plant inside your high tunnel?

      1. Plant inside the tunnel when the soil temp is above 50 degrees and the air temps inside do not get blow freezing. I understand this is easier said than done.

        1. I recommend talking to an experienced grower in the area and they can help you better pinpoint that time.

        2. As a rule of thumb you should be able to plant/transplant in your tunnel 2-4 weeks before you normally plant outside.

      2. Tip: You may want to purchase some frost cloth/blanket to cover your plants on a cold night. This is North Dakota and anything can happen, it is better to be prepared than scramble if the forecast calls for a late freeze.

  4. Temperatures will need to be monitored daily. If the sides are not rolled up and/or doors opened it will not take long for temperatures to reach over 100 degrees on a sunny July day.
    1. This will mean someone will need to be responsible for monitoring temps and rolling up sides on a daily basis.

    2. On the ends of the season May – June and September – October are times when temperatures fluctuate the most. This time it is especially important to monitor temps and you need to be prepared to open up or close the tunnel depending on weather.

  5. Water;
    1. This may seem silly, but it does not rain in the high tunnel. Mother nature may take care of watering the plants outside, but you are the only one that can water the plants inside the high tunnel. Laugh if you want, but the first time it rains I will bet you will catch yourself saying it rained today I do not have to water.

    2. You will discover that plants in the high tunnel will grow faster than plants outside. With the fast growth, plants will require lots of water as compared to their counterparts outside.

    3. Limit or eliminate overhead watering. You will also discover that it will be more humid in the high tunnel vs outside. To help eliminate the spread of disease it is recommended to use drip irrigation, soaker hoses or hand watering at the base of the plants. Keeping the foliage of the plant dry will reduce the risk of your plants getting a foliar disease.

  6. Trellising
    1. To maximize space you should trellis your tomatoes and cucumbers. Trellises also work well outside.

    2. Do not use the high tunnel skeleton to support your trellis unless your high tunnel manufacturer said you can.

    3. If you have never built a trellis before there are many you-tube videos or examples In the books I sent you.

    4. I trellis my cucumbers in my home garden and all I use is T-posts spaced about 6 feet apart and tinsel twine, run horizontally to the ground about 4-6 inches apart. When I am done it looks like extreme fencing. As the plant grows, I weave the stem through the string. I had used wire but at the end of the season it was a pain to have to remove the wire. Now all I do is cut the twine and throw everything away the twine will breakdown, just a tip.