Hi, I'm Heidi Rader, here in the Alaska Garden.
I'm with UAF Cooperative Extension Service and Tanana Chiefs Conference. And today
I'm gonna be talking all about high tunnels. So I'm here at a high tunnel here in Fairbanks, Alaska.
This is a 30 by 72 foot gothic style high tunnel.
High Tunnels are great because they extend our short growing season and also increase the temperatures.
For the growing season inside. They're low cost
structures relative to a greenhouse and they're actually considered temporary structures too.
So this one's in a power line and that would not be possible if you had a greenhouse.
So per square foot, they're pretty cost effective. High Tunnels are usually
manually ventilated or passively ventilated and
you don't usually have grow lights inside high tunnels or cement flooring. You're also
growing right in the ground usually in high Tunnels, so
this one has two different sizes of doors . One is big enough to
actually have a tractor go inside and till. You can also till with a rototiller. And usually in greenhouses
You're growing in containers or in raised beds.
And so if you need to replace the soil, you have to manually
carry in that soil, and replace it. So that right there saves a lot of time, as well for a high tunnel.
So, other styles of high tunnels are quonset hut shaped and
those ones can be the cheapest structure, but they don't shed the snow quite as easily. And
It's harder to go too wide with that type of structure too. But the nice thing about quonset style
is that it keeps the the warm air closer to the plants. With the Gothic style, the
air rises to the peak and so it's not quite as warm low down,
but the gothic style sheds the snow a little bit easier than the quonset hut style.
It's also easier to work on the sides because you have more headroom to work, and so you can stand up a little easier.
Another style, that's actually considered a high tunnel for the purposes of the Natural Resource Conservation
Service, is a round type greenhouse style. And that's really good for very windy conditions,
but it's difficult to grow things in a round,
in round paths. So I mentioned the Natural Resource Conservation
Service or NRCS, and they've got a great program that can help you with the costs of the high tunnels. It's part of their
Environmental Incentive Program to protect soil and water. So let's go ahead and go inside this high tunnel.
So it's fall here in Fairbanks,
and so you immediately feel the temperature difference inside. The temperature
differences in high tunnels can vary quite a lot
throughout the day, as well as throughout the summer. And so you can have a
very dramatic
temperature changes quite quickly from, you know, say 8:00 in the morning to noon in the morning when when the sun is highest and
temperatures can rise pretty dramatically if the sun is out, versus if it's cloudy. And
this high tunnel actually has two layers of plastic and
a blower is used to force air in between those layers which adds quite a bit more
additional insulation.
Another thing you could do too to raise the temperature, is use a combination
of season extension techniques, so
you could use plastic mulch inside. You could also use a low tunnel,
Which is basically
plastic covering just one row of plants and
And you can use any number of other combinations.
The more layers of plastic that you add, you are going to cut down on your light
transmittance. And so, say if you add two layers versus one layer of plastic,
you're gonna cut down your light transmittance by about 10 to 15 percent.
As the plastic ages,
usually the plastic,
this is six mil greenhouse plastic. This will last its warrantied to last four years. As it gets older though,
and you have more dirt
on the plastic, you're also cutting down your light transmittance a little bit. So these high tunnels,
they come in a kit. This one cost about seven thousand dollars, but it was also seven thousand dollars for shipping.
And then the end walls were were built separately and you can do any number of
custom
configurations for your end walls. This one, I really like this design of this one, with
the door for walking in, as well as the door that's large enough for the tractor to go in.
So,
the high tunnel extends your season quite a bit.
You know you might be growing in here by about mid April and as late as October
or even November. And again that's partly because this high tunnel has two layers of plastic where you can
force the air into it.
And some very frost sensitive crops will probably that be the first to die,
but of course, you could grow cool-season crops even... even later than some of your warm-season crops in these structures.
Um
And not only can you grow
longer
things will do be more productive during this season because
the temperatures are higher. So you can see there's melons growing in here.
Tomatoes.
Got a quite a few ripe ones here. Cucumbers
and strawberries.
So,
growing warm season crops in a high tunnel makes a lot of sense because they they like the warmer temperatures
and they need longer seasons for maturing, but if you're a farmer you also want to consider
the higher value crops. So you could of course grow broccoli in here,
but it may not like the warmer temperatures.
And it's not a particularly high value crop
So it probably doesn't make sense to grow that in a high tunnel unless you want to push this season.
So some of the benefits of the high tunnels, as I said, you know, you may be increasing your temperatures
five to ten degrees depending on the time of day and the season.
But you're also protecting your crops from too much rain,
from wind, and you're increasing the humidity inside the environment too.
You're also protecting from hail and
unseasonable frost's. So if you experience,
say a midseason, frost in some areas of Alaska,
It may kill all of your garden in the middle of summer. Or even if you experience early frost,
but the temperatures don't drop overall, you can still extend your season quite a bit, and you have some
protection against those
unpredictable weather conditions.
Some people even grow cut flowers in high tunnels and and that's a good way to go because
cut flowers are very sensitive to hail or rain and that type of thing. So...
and for your vegetable crops when you use drip irrigation,
you minimize the splashing of water and so it keeps your crops really clean. You get to do less washing
and it keeps the moisture down on the leaves, as well
which can minimize some of the pests and disease that you would otherwise see with the increased moisture.
On the other hand that can be a challenge with growing in a high tunnel, is
when you get later into the season, and you're trying to keep the temperatures as high as possible and conserve your heat,
you can have quite a bit of moisture buildup in the high tunnel.
And without a lot of
active ventilation, it can be challenging to mitigate that moisture.
So let's go ahead and and go down the row here and look a little more closely at what's growing in here.
We've got snap beans in here. That's another warm season crop.
Cucumbers and tomatoes are usually grown in greenhouses and
so in the high tunnel,
you're able to grow them in here and have a lot more
growing space than you would have in a greenhouse at a much lower cost.
And another thing that's done here is when strawberries are being grown,
these are grown in old gutters and you can see there are three layers of strawberries, so
this is a way that
space can really be saved with growing these strawberries. And
strawberries, cucumbers, tomatoes, they're their high-value
crops, so if you are a farmer those are great ones to grow in your high tunnel.
You can also grow things like lettuce or cool season crops and try to be the first one to the market
with those grains and get a higher price as well, but you can see here this one has bolted and
in the high tunnel the temperatures could be too warm for some of those cold season crops like lettuce as well.
Another great crop to grow in high tunnels are peppers. They do really well inside the high tunnel.
Usually bell peppers or sweet peppers are really difficult to grow outside,
here in Alaska. And of course you can grow them in a greenhouse as well
but you have a lot more space here in the high tunnel. So we've got a couple different varieties here.
Carmen, this one's Lipstick, and
we've got some some hot peppers as well. And you can see they're ripening and it's not even September and usually they need a
growing season that's too long for Alaska, and especially here in Fairbanks.
So today we've been talking about high tunnels. Check out our other videos. I'm Heidi Rader here in the Alaska Garden. Thanks for joining.