High Roof Tunnel Farming
Tunnels: We averaged 30 man-hours to put up the tunnels including driving the anchor posts. Expect to add additional time if you have to assemble the hoops from pieces. While we liked the 26’ by 96’ tunnels better than the 20 foot ones, we found them much more difficult to put up due to the added height. Once they are up, the taller 26’ wide tunnels, are much more comfortable to work in. We did not even consider moving the large tunnels and bought two new 20 X 96 foot tunnels instead. They were much easier to assemble and move in midseason. While they were not difficult to move, we did find that the plastic did see some damage from the wobble wire and because we could not get the plastic back in the same area, the cover was weakened. To move the tunnels to the new location would take about 25 man-hours. If I were to do it again I would look into some sort of tracking system that would allow the tunnels to be moved forward and anchored as a complete unit. To do this you would have to have a large level area to allow for such a move. Keep in mind that it has to be anchored very securely to the ground to resist wind damage.
Strawberries: Berries were planted in 2002, during the summer, in the late fall, and in summer of 2003. They were planted in double rows under white plastic with drip irrigation.
We began the growing process on 4/15/03 by lowering the plastic to accelerate the growth of the berries. We needed no artificial heat during the entire berry season. We would put the sides down in the afternoon before sunset to hold heat in. In the morning we would elevate the sides to keep tunnel from overheating. One needs to be careful to not cook the plants, yet maintain an appropriate growing temperature. On cold nights we would also use floating row cover over the plants in the tunnel as an additional protection.
We were exceptionally pleased with the results of strawberries grown in the tunnels.
- Berries were cleaner
- Very few deformed berries
- Foliage stayed green and clean throughout the season
- Berries were some of the sweetest berries we have ever grown
- Size was excellent
- Ripening of berries
- Tunnel berries began 6/1/03
- Berries in plastic mulch under floating row cover began 6/11/03
- Berries without plastic mulch or floating row cover began 6/26/03
- Tunnel berries were
iii. Less distorted
v. Had less pest damage
vi. All three varieties did well
- Berries under plastic mulch and floating row cover but not in tunnel
i. Fair quality
ii. Severe turkey and coon damage
iii. Suffered frost damage
iv. Large amount of distorted berries
v. Honeoye was only variety that produced quality berries
- Berries outside of tunnel without protection of any kind
i. King berry blossoms all froze
ii. Flavor was poor
iii. Berries were soft due to rains
iv. Berries all came in at once due to heat
v. Competition was severe at the market
vi. Most berries went to waste because of sudden ripening.
vii. Honeoye were only berry variety that produced quality berries
- Production records of berries inside tunnel verses outside tunnel (Records were taken on the two test plots that were grown identically with only difference being the tunnel.)
i. Early glow showed a 200% increase in tunnel
ii. Honeoye showed a 380% increase in tunnel
iii. Jewel showed a 330% increase in tunnel
- Production difference between two tunnels (Tunnel one had leaf mulch placed between the rows and Tunnel two did not)
i. Early glow showed a 22% decrease where no mulch was used
ii. Honeoye showed a 10% increase where no mulch was used
iii. Jewel showed a 50% increase where no mulch was used
iv. Berries began production and had heavier production in the beginning where no mulch was used
v. Berry production peaked at the same time in both tunnels
- Berries started previous summer, and late fall production record.
i. Tunnel one where leaf mulch was used between rows.
1. Late fall planting produced 42% of early summer planting.
ii. Tunnel two where no mulch was used between rows.
1. Late fall planting produced only 11% of early summer planting.
Berry sales were excellent, with the one exception that we could not fulfill demand. The berries were early, clean, large, extremely sweet and very aromatic. The customers noticed the quality and commented that they were the best berries they had ever had. Picking was at a slower pace due to a steadier ripening taking some of the stress out of picking. Because of the Saturday Farmers Market, we time pickings to be on Friday. On two of those Fridays there was heavy rain. What a pleasure to be able to enter the tunnels and pick nice dry berries. Had the berries been outside of the tunnels, we would have lost all those berries or, at best, would have missed our market day. In one area, the ground was lower than outside of the tunnel and water did flow in and damage a few berries. A few times it was hot and humid within the tunnels during picking. Picking could be done earlier in the day, due to lack of dew on the plants.
Raccoons and turkeys were a problem both inside the tunnels and outside until we used a portable radio. The test area out of the tunnels did not benefit as much from the radio. We assume the echo within the tunnel enhanced the effect of the radio. Lowering the sides at night also helped to avoid the early morning and late afternoon raids by the turkeys as well.
We did not find any bees or insects during the first blooming of the berries. But we did see a large number of spiders walking on the blossoms. Later on, we found that a very tiny type of bee and flies were quite active among the plants. Very few honey bees or bumblebees were observed. We used no mechanical pollination methods. A lot of the insects that did enter the tunnels seemed to get disoriented and were unable to find their way out. They would fly up and bounce off of the top of the tunnel until they gave up or died. The bumblebees in the fall were able to enter and exit without getting disoriented.
We supplied about ½ inch of water per week during the fruiting season. Possibly should have done more.
We observed no tarnished plant bugs until towards the end of the crop season within the tunnels. Outside the tunnels, we did observe more insect damage. It seemed the early ripening avoided much of the typical fruit damage by insects.
In the tunnels we did observe a slight increase of slug damage and an increase of spittlebugs, but nothing of great concern.
Workload: One of the nicest benefits of the tunnels was the benefits to me labor wise. We found that the extra hours gained by using tunnels were the biggest bonus of all.
- The tunnels extended my working window by about 60 days.
- The tunnels gave me an extreme edge on marketing my crop.
- The tunnels allowed me to reduce the acreage and amount of crops needed to accomplish the same goal previously sought.
- The tunnel gave me more freedom to deal with weather extremes.
- The tunnel allowed me to spread out the harvest times of my crops.
- I was able to avoid most of the periods of glut where competition meant produce was taken and then not be able to sell it.. There is nothing worse than to have a good yield and find it not able to sell. This was virtually eliminated.
Potatoes: We could not screen out the bugs because the material we used caused the tunnels to overheat. So we did not use any bug barriers. We found no marked difference between the tunnel and the test crop outside of the tunnels. No blight and very little potato bug problems were observed on either test plot. This was surprising, as we have always had bug and blight problems in prior years. Potato color was excellent and size was acceptable. On a positive note, we did notice that our Yukon Gold potatoes were the best we ever grew and they had no hollow hearts. We may try some early potatoes next year but not a whole tunnel full. Yields were the same in or out of the tunnels.
Raspberries: For some reason, the berries ripened quite late this year. We did not get any ripe berries until September 26th. On October 1st the weather turned cold and our test plot outside of the tunnels froze, destroying any hope of a berry crop. Being in the zone 4 area , that is a common problem with fall berries.
The berries within the tunnels, however continued to produce up until November 2nd. There were two nights where we placed portable heaters in the tunnel. We used approximately 20 lbs of liquid propane total. The berries in the tunnels were of excellent quality and size. The flavor varied depending on the temperature within the tunnel. Sun and warmth play an important part in producing flavor. If a grower is able, he could enhance the flavor by spending more time regulating the temperature during the day. I elevated the sides during the day to allow for bees to enter, and often that allowed the temperature to cool off too much. It is feasible to leave the sides down to maintain a higher temperature within the tunnels providing one does not let the temperature get too high so as to cook the berries.
We faced no wasp problems, as I had feared. The primary pollinators were small bumblebees, which did an excellent job. The canes kept blooming right up to the day the plants were killed by cold in November.
Production was good up until the end. The volume of berries on the plants kept increasing up until the day they froze.
We decided to let the berries freeze on the 2nd of November because the weather forecast called for continued cold for over a week, and we felt the cost of heating the tunnel at night would be too high to warrant us doing that for a prolonged period of time.
Turkeys were a big problem with the berries outside the tunnel. A transistor radio playing in the tunnel seemed to do the job of keeping critters out.
We gained 4 extra weeks of berry picking through the use of the tunnels.
The berries sold well and had excellent shelf life.
Other crops grown in the High tunnels:
Tomatoes: We were able to harvest about 20 lbs of tomatoes per plant using a determinate beefsteak variety. The tomato plants in the tunnel gave us a very clean, large, crack free tomato. Flavor was excellent and the tomatoes seemed to have a higher sugar content. Because the plants were kept dry, we noticed no disease problems. Watering was done through drip tape laid under the plastic mulch.
(Drip tape is an excellent method of watering if you do not have running water available. The tape requires very little pressure and thus can be gravity fed by a water tank hauled to the site on a trailer) I strongly recommend plastic mulch in a tunnel, as this reduces evaporation and allows for less stress on the plants. Caution should be made to not plant tomato plants too close together as this could bring about disease and pests problems. We try to keep plants between 18” to 24” apart in rows that are 4’ apart.
Cucumbers: Cucumbers are a great crop in the tunnels and the flavor is great. Use varieties that do not require pollination. Be sure to supply some sort of support for the vines to climb on. Water must be supplied consistently to maintain quality cucumbers.
Peppers: I believe peppers are the most trouble free vegetable in the high tunnel. Yields are exceptional. Be careful to keep moisture even throughout the season and don’t water too heavily at one time. Keep in mind, if you leave the peppers to turn red, you will substantially limit production. Also consider pruning off deformed, blemished peppers as soon as you see them. Why weaken the plant with valueless produce?