Keep the Soil in Your High Tunnel Healthy

Unheated high tunnel, or hoophouse, production is being practiced more widely because it is a profitable way to grow and sell year round. That requires extra attention to, and management of, soil health, as this Backyard Riches member explains.

Courtesy of Adithya Ramachandran, Kaleidoscope Vegetable Gardens, Dundurn SK

One of the challenges of high tunnel production is that there is no natural rainfall to leach the soil. Although I collect rainwater, it supplies only 20% of my high tunnel irrigation requirements. The other 80% comes from municipal water. So there are three main concerns I deal with.

1. Saskatoon city water, which supplies my farm, contains 142 ppm calcium/magnesium carbonates. Every inch of irrigation adds about 0.75 lb of lime per segment. At the rate of 1? of irrigation per week for 6 months a year, this works out to 20 lbs of added lime per segment, which can raise the soil pH and cause production issues. To neutralize this, I till in 10 lbs of organic sulfur per segment per year.

2. Saskatoon city water contains 13 ppm of chloride and 2 ppm of chlorine. Chlorine reacts with soil organic matter to form chloride. Outdoors, this is leached by rainfall. In a high tunnel, this works out to 2 lbs of added chloride per segment over 6 months of irrigation. To counter this, I try to include beets or chard in the rotation at least once every two years. These crops can ‘mop up’ significant amounts of chloride.

3. Soil organic matter is consumed very rapidly in high tunnels. I add composted manure, compost and alfalfa meal at least twice per year to compensate.

SF photo guest blog Adi hoop house

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Early Spring Marketing Using Unheated High Tunnels

Courtesy of Adithya Ramachandran, Kaleidoscope Vegetable Gardens, Dundurn SK

Most farmers underperform at early spring markets. SPIN-Farming is based on generating strong cash flow by targeting $1,000 weekly sales – in late April or early May – regardless of your growing zone. To do that you need to ignore conventional gardening practices, and get into production early, in volume. Adithya Ramachandran’s Kaleidoscope Vegetable Gardens, is in zone 3. Here is what he went to market with May 7.

SF photo fb early spring market Adi

Adi is using unheated high tunnels..and improving his production strategy all the time. Read below.

This spring has been an interesting learning experience. There are some things I would do different next year, including increasing my staggering time for radishes, and a greater focus on beets, green garlic and kohlrabi to target late spring sales.

Something else that I would like to try out next spring is an early planting of broad beans for bean production. I noticed that the ones I seeded in March were flowering now. However I tilled them all under because they were planted densely for shoot production (I didn’t get around to harvesting them all), and they wouldn’t have done well.

I also plan to diversify my spring sales next year with tulips.

Find out how backyard farmers get off to strong spring production and sales in early spring in the SPIN online support group. Receive free trial membership with the purchase of any SPIN guide. 

How to Determine Hoophouse Density for Tomatoes and Peppers

Courtesy of Adithya Ramachandran, Kaleidoscope Vegetable Gardens, Dundurn SK

When growing tomatoes in a hoophouse, think about how many plants you would grow on the same amount of space outdoors, divide that by 3, and plant only that number in the hoophouse. This is particularly important for tomatoes because they can get HUGE in a hoophouse. I learned that the hard way my first year with high tunnels. Not only does it make it difficult to work in there, but it also increases disease and pest issues, and they compete with one another for water and nutrients. You can improve your yield per square foot by planting fewer plants. This is particularly so if you don’t prune the plants (which I don’t do – too labor-intensive).

Peppers don’t get as crazy as tomatoes, but they also consume a lot of water and are very shallow-rooted, so again there can be competition if they are crowded.

SF photo fb wisdom Adi hoophouse densifty photo

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Become Your Own Weather Forecaster

Courtesy of Adithya Ramachandran, Kaleidoscope Vegetable Gardens, Dundurn SK

High tunnels require farmers to become their own weather forecasters. In the Saskatoon area, tonight’s forecast low is -13 C (8.6 F). That’s a little too cold for most cool-season crops, so we spent part of last week laying down row cover – 8000 sq ft of it. The cover also accelerates germination.

I’ve kept temperature records in past seasons to determine the effectiveness of row covers. Based on variables such as afternoon soil temperature at a standardized depth, number of layers of row covers, soil moisture status, and height of row covers above
plants, I came up with a few formulas for determining what the overnight low will be.

For example, today’s soil temp. at the 4′ depth is 10 C inside tunnels. I expect it to rise to 14 C by late afternoon. 14 – (-13) is 27. For a single layer, I use a factor of 0.35. 0.35*27 is 9.5. 9.5 + (-13) is -3.5 C (26 F). That is my forecast low underneath the row cover.

For double layered row cover, I use a factor of 0.45. That gives me a forecast low of -1 C (30 F). Sunflower greens are the only crop to get double cover – all other cool-season crops should be fine with one layer.

SF photo guest blog Adi weather forecast

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Planting Plan for an Early Spring $1,000 Market Week

Courtesy of Adithya Ramachandran, Kaleidoscope Vegetable Gardens, Dundurn SK, Canada

It looks like spring is arriving early this year in Saskatoon. My first plantings in high tunnels typically go in during the 4th week of March, but I may be able to plant a little earlier this year. Therefore now is a good time for me to start transplants of beets, chard, kale and spinach. In early March, I will turn on my irrigation system and water all my tunnels heavily as they tend to dry out over the winter. Irrigation also speeds up the thawing process inside the tunnels. I also give myself an early-season workout by rolling in wheelbarrow-loads of snow for extra moisture.

SF photo guest blog Adi spring planning

 

Direct-seeded cool-season crops such as turnips, kohlrabi, radishes, onion sets, dill, cilantro and (more) spinach will go in after the transplants on a staggered basis. Later in April, I will also seed Quick Greens such as sunflowers and broad beans. The combination of all these crops will allow me to target at least a $1000+ marketing week in early May. For that week, I am targeting the following at $3 per unit, or 2 for $5. Because demand is high in spring, I usually don’t offer a 5 for $10 deal.

  • 75+ units of radishes
  • 75+ units of scallions
  • 75+ units of spinach
  • 75+ units of kale
  • 50 units of Quick Greens
  • 50 units of other greens (baby chard, baby beet greens, turnip greens or salad mix).

In mid-April I start transplants of warm-season crops (peppers, eggplants, tomatoes) for my summer relay. Unlike with cool-season crops, I avoid taking risks with these crops and always wait until early June to transplant into tunnels.

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