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When cold weather arrives, it brings the end of the vegetable gardening season for many of us. That doesn’t have to be the case though. On this week’s Good Growing Podcast, we discuss how we can expand our growing season beyond what's normal by using season extension. Learn about what season extension is, why we would want to use it, the different techniques you can use, and more!
Watch us on YouTube: https://youtu.be/B2REiv1lFYc
Skip to what you want to know:
00:31 – Welcome, Ken. What are our vegetable gardens looking like?
03:05 – What are our experiences with season extension?
04:25 – What is season extension?
06:20 – Effect of daylength on plant growth
10:25 – What kind of crops are we talking about when it comes to season extension?
13:26 – Cloches
16:27 – Temperature/heat management
17:55 – Floating row cover
22:00 – Low tunnels
24:05 – High tunnels and caterpillar tunnels
34:20 – Greenhouses (controlled environment)
37:20 – Cold frames
40:25 – Hot frame
41:46 – Starting seeds indoors
43:10 – Wrap-up, thank yous, what’s up next week, and goodbye!
How to Build a Low Tunnel Part 1 - Bending low tunnel frames
How to Build a Low Tunnel Part 2 - Installing greenhouse poly plastic
How to Build a Low Tunnel Part 2 - Installing greenhouse poly plastic
Contact us!
Chris Enroth: cenroth@illinois.edu
Ken Johnson: kjohnso@illinois.edu
Check out the Good Growing Blog: https://go.illinois.edu/goodgrowing
Subscribe to the weekly Good Growing email: https://go.illinois.edu/goodgrowingsubscribe
Any products or companies mentioned during the podcast are in no way a promotion or endorsement of these products or companies.
Barnyard Bash: freesfx.co.uk
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Creators & Guests
What is Good Growing?
Talking all things horticulture, ecology, and design.
Welcome to the Good Growing podcast. I am Chris Enroth, horticulture educator with the University of Illinois Extension, coming at you from Macomb, Illinois. And we have got a great show for you today, season extension. Taking the shoulders of the growing season and pushing things out to there and maybe even beyond. And you know I'm not doing this by myself.
Chris Enroth:I'm joined as always every single week by horticulture educator, Ken Johnson in Jacksonville. Hey, Ken.
Ken Johnson:Hello, Chris. It's finally finally starting to cool off.
Chris Enroth:It got cold last night. Yes.
Ken Johnson:Finally time for that season extension stuff now.
Chris Enroth:I think so. Yes. Well, the so the predicted low last night was 30 degrees. And I saw that, and I said, okay. I'm gonna go out.
Chris Enroth:I have all my poblanos. I have my tomatoes. I have everything that's just sort of been sitting there. And I harvested everything last night, pulled it out, brought my rosemary inside, and, it did not get down to freeze. There were some rooves this morning that had a little bit of frost on them, but nothing on the ground.
Chris Enroth:Not nothing there. So that's okay. That's okay. I I I'm okay with I I'm done. This is, I'm done gardening, so the year is done for me.
Chris Enroth:Did did you get any, frost last night in Jacksonville?
Ken Johnson:There's a little we've had a pillow on the deck drying, and there is some frost on that
Chris Enroth:Mhmm.
Ken Johnson:This morning. But looking at lunch, it looks like tomato plants are still fine
Chris Enroth:Yeah. And stuff. Everything is fine. Everything is fine. I probably could've left it on there because now we're supposed to get a little bit warmer again.
Chris Enroth:And so I probably could've pushed a little bit longer, but you know what? I I think at least tomatoes, the ones that I harvest late in the season that have been exposed to a lot of cold, I don't think they taste as good as those that are growing in the summer. Do you do you notice any texture or taste difference in your fall tomatoes versus, summer?
Ken Johnson:Usually, by the time fall rolls around, I'm so sick of tomatoes.
Chris Enroth:Yes. Yeah. I I just throw them at the kids. Yes. We take them to plays, and we throw them at the actors.
Chris Enroth:Yeah. Mhmm.
Ken Johnson:I I haven't so so so the purple tomato putting stuff on, and I've picked some, and they're just sitting on the counter. I haven't tried one yet.
Chris Enroth:Yeah. After that I I tried one the other night. It did not taste as good as the, the summertime harvest. So it yeah. The remainder of my purple tomato are going to seed, which I've done multiple times, and my wife keeps throwing out my seed thinking that it's like like, what is all this stuff on this paper towel?
Chris Enroth:Or why do you have this jar of, mold on the kitchen counter? I'm trying to save tomato seeds, but
Ken Johnson:I have to do it in the office.
Chris Enroth:I know. I have to do it here. Oh my goodness. Well, I I guess we should, you know, dive into the topic of the day because that's kind of what we we're we're talking about. We're talking about gardening this time of year and what to do.
Chris Enroth:Now I have, for several years, can I I've done many of these practices before? Only recently, maybe the last, like, year or 2, have I really kind of put the brakes on when it comes to season extension. I guess I just get tired of gardening. Like you said, tomatoes don't taste as good anymore. You you wanna do something else.
Chris Enroth:But, yeah, do you do you what's your experience with season extension?
Ken Johnson:So a little bit for our the ginger stuff we were doing. But other than that, like, in personal garden, you know, we'll cover plants with the blanket, and that's about it. We've we've talked about it, but, you know, it's one of those things falls gets fall gets so busy that Mhmm. By the time things start slowing down again, it's it's almost too late to do it. So it doesn't get down.
Chris Enroth:Yeah. Well yeah. So I I think we're in the same boat. You know? There's all these not only the school start, all the other school related activities start as well, and you just run out of time by the end of the week.
Chris Enroth:So I I think it might be a good time then let's define what season extension really is, as we keep talking about it. Ken, could you illuminate us, please?
Ken Johnson:Yes. So like you mentioned, you know, working on those those shoulders. So kinda early in the year, later in the year when typically I I think usually more warm season crops or even cool season crops, just being able to grow those longer or earlier in the season than we typically would. Capturing the heat that we get during the day, through various structures or materials, capturing that and holding that on through the night. We get those colder temperatures and that can radiate from it's in the air, it's in the soil, and capturing that heat to to allow those plants to survive conditions they may not be able to.
Ken Johnson:This is kinda how I think it. Just keep that gardening season going a little bit longer than you would normally be able to.
Chris Enroth:Yeah. You're you're catching photons as I like to say. Catch or capturing sunlight and converting it into heat energy. And, when you look at graphs of kind of the the ambient air temperature on outside of these structures versus the air temperature on the inside, when you start out the night, they're usually way up there, you know, much higher than the nighttime temperatures outside. But as without the sunlight actively warming that structure, the the two lines very often come very close together towards dawn.
Chris Enroth:And, really, the goal of anyone using season extension is really just making sure that you keep that that that inside air temperature from hitting, you know, freezing or or you subfreezing temperatures, and and just give it a little extra ounce of protection.
Ken Johnson:Yeah. You usually, you're basically you're extending it a couple weeks. Mhmm. Maybe a month if you're lucky. You're not without without providing supplemental lighting and stuff like that, we're not gonna be doing this.
Ken Johnson:Well, you can do it, but your your plants aren't gonna be actively growing. Because that once we hit about 10 hours of daylight, plants once you get less than that, plants don't really put on any growth. They just kinda sit there. And if we're here we just look this up before we started. For Jacksonville, our last day for 10 hours of sunlight is gonna be November 14th, and we will not hit 10 hours of day length again until January 27th.
Ken Johnson:So, you know, rest of November and almost the end of January. If we are keeping plants warm enough to keep them alive, they're just kinda sitting there. They're not necessarily actively putting on, new growth. So we'd be able to kinda hold a crop, but we're not necessarily producing a lot more of it. Mhmm.
Chris Enroth:Yeah. I think that's kind of the one of the the drawbacks, if it is a drawback, is that people think, oh, I will be actively growing these crops in the winter months. Like, I will plant a seed right now in November, and I will have something to harvest in January, February, and that's really not the case. A lot of these crops need to be started well before today. So I can well, we're recording November 12th.
Chris Enroth:Let's see. November 12th is actually where I'm at here in Macomb, our last 10 hour day of daylight. And so we will not get above the 10 hour mark here in Macomb until we reach January 29th. And so it it is this is, you provided a a website where people can type in their location data, Ken, and and folks want to. They can look up their own daylight or also measures darkness too, whatever you want.
Ken Johnson:Yes. It's the US Navy Astronomical Applications department. And you can just put in your your latches longitude and latitude. And if you don't know what that is, they've got a little thing. You can put your your city in there, and they'll plug it in for you.
Ken Johnson:And it'll tell you how many hours of daylight or night you have or darkness for every single day of the year. Going you can do it back to 1700. And as far in advances 21100.
Chris Enroth:I I I could probably spend some time looking at is this is it it folks, this is literally a chart of numbers. This is nothing fancy. There's no fancy graphic, but I think this is so cool, especially when you look at the solstice, time frames. So, you know, I grew up thinking, oh, winter solstice, that is the shortest day of the year. Summer is the longest day.
Chris Enroth:But when I look at these numbers, it's, it's really interesting. It's like when the Earth's axis hits its maximum, it sort of, like, sits there for several days. And so we have, from and here in Macomb, we have from December 17th until December 25th. Those are the shortest days of the year. It's like, you know, 1, 2, 3, 4, 5, 6, 7, 8, 9 days where it is at 9 hours and 17 minutes.
Chris Enroth:It's like we're just sitting there at that maximum point, and then the Earth pivots back in the other direction. And it does the same thing with the summer solstice. So here I thought December 21st was the shortest day of the year. It's actually a span of days that are the shortest, though. I could I could look at this all day, Ken.
Ken Johnson:So you don't notice the minutes. Maybe that's maybe it's actually a few seconds shorter.
Chris Enroth:Yeah. Yeah. I well, now you burst my bubble. Okay. I gotcha.
Ken Johnson:We we can cut that part out. That's for 10 minutes.
Chris Enroth:Cut that part out. No. That's an important learning experience. Yeah. We we grow from our what we've learned here.
Chris Enroth:So well, good point. Yes. This is minutes. Doesn't include seconds. It's there is probably, tiny little fractions.
Ken Johnson:In the grand scheme of things, it doesn't matter.
Chris Enroth:Yeah. Your plant probably doesn't care that much, in terms of seconds, but, minutes, definitely hours. That does impact them quite a bit. Well, Ken, when I am growing things for my in my season extension experience, I've not really ever been growing tomatoes or, like cucumbers. It has been a a a serious effort of growing cool season crops and not those warm season crops.
Chris Enroth:But I would say season extension in the springtime, for me, that would probably involve utilizing more warm season crops, maybe getting an area prepped, warming that soil ahead of time so maybe I could transplant tomato starts sooner than, if I didn't have a season extension device over it. But when it comes to fall, like we've both said, we're kinda sick and tired of those warm season crops. I am of the opinion that fall or cool season crops taste better when they're growing in the fall because as we get cooler, those those crops produce more sugars. It's like the natural antifreeze. I just think they taste better.
Chris Enroth:Like, even kale can taste good as it it gets hit by a little bit of cold there. Yeah. Oh, you think that's funny. I think this kale could taste good sometimes. It's a little bit sweeter, but spinach definitely gets taste better.
Chris Enroth:Carrots can taste better. A lot of these crops, I these cool season crops, I think the the cooling weather enhances their flavor. So that's that's the types of crops that I try to focus on with season extension.
Ken Johnson:Yeah. I think I've seen you know, there's charts and stuff out there, you know, which ones do well. I mean, spinach is always on there because that's very cold already. I mean, that can take a a harder frost on its own. You don't necessarily need the protection.
Ken Johnson:Parsnips are on there usually. Carrots was I think the the tops can handle like 10 degrees. The roots themselves can get down to the thirties. So Mhmm. So, yeah, it's you almost kinda for some of them, it's almost if you're extending, that's almost like building a giant refrigerator.
Ken Johnson:It's kind of Mhmm. Just lengthening that harvest.
Chris Enroth:You're you're yeah. You're just trying to keep the snow off them so you can harvest them or pick them whenever you feel like it. Now I would say it is recommended whenever you're harvesting crops in the winter, you wanna try to avoid harvesting them while they're frozen. So like spinach, it will freeze, and it will wilt, and same with some kale and things like that. But as soon as it it gets above freezing, the, the the water in the leaves rehydrates the cells and and they the plant perks back up, and so you can harvest then.
Chris Enroth:So that that would be one piece of advice is avoid harvesting while the plants are frozen. It can be freezing outside, but still be above freezing in your season extension device. So you can still do it, but, it's something to be mindful of too.
Ken Johnson:Get into the the different devices now?
Chris Enroth:I guess so. If people really wanna know what season extension devices are, yeah, we should probably do that. Yes.
Ken Johnson:So I think the first one we have on our list are cloches Mhmm. Which I think is French for bell
Chris Enroth:Yeah.
Ken Johnson:Or something like that.
Chris Enroth:They're like these big glass look bell looking things that they used to put over plants.
Ken Johnson:Mhmm. Just those I think that was, you know, originally, that was for more wealthy people doing that because they could afford these big glass bells to cover. And usually, with closures, a lot of times you're you're doing them on individual plants. So if you've got 25, whatever, broccoli plants. Probably not the most practical way.
Ken Johnson:Those would be some pretty big cloches too. But nowadays, you know, you could still find the glass ones. There's plastic ones. You can I've seen, soda pop bottles, whatever you wanna call it. 2 liter, 3 liter bottles, milk cartons, like wax paper.
Ken Johnson:People make cones out of those and put it over there. The wall of water, you may see that that's like plastic sleeves that you fill with water. A lot of times you use that more in the ice seed advertise more for for, like, spring, like tomatoes. Getting tomatoes out early where you fill that with water, that water traps some of that heat and releases that throughout the night, keeps those tomato plants a little bit warmer. So there's a a variety of different ways you can use use and and materials you can use, for closures.
Chris Enroth:Yeah. I always thought the the wall of waters were interesting. It it it does make sense because it takes more energy to heat up water, which means it would take longer for that heat to dissipate from that water. So and and, again, you know, it might work out too in that case because we're really I mean, we're talking about just, like, 1 or 2 degrees worth of protection really by the end of the night as we approach dawn. That that that's really the critical moment, making sure that we're just a little bit higher than that outside temperature, that we're not, hitting either that freeze point, you know, with when it comes like tomatoes and peppers, you know, we we really don't wanna dip into freezing weather, minus 32 degrees Fahrenheit.
Chris Enroth:But some of our cool season crops, as we've already described, they can tolerate freezing or below freezing, but they all do have their thresholds. A lot of times, for some of those cool season crops, it really does vary and depend. But, like, with with our spinach and our carrots and some of our kales, you know, we're looking at, like, 20 degrees Fahrenheit. If we dip down below that and we're in the open, we're not in any protective structure, they could also start seeing damage, dying, things like that. So, yeah, research your individual crops to know what those minimum temperature thresholds are.
Chris Enroth:And yeah. I was thinking I had a chart, but I don't think I have a chart. Never mind. Don't put that in there because I don't have a chart to show people that's mine. It belongs to Johnny Seed.
Ken Johnson:And and with closures and when we get into some of these other ones too, well, for closures because they're usually smaller and you're doing one plant, make sure it's heavy enough or it's anchored so it's not going to get blown off. And you've got a way, you know, if you're using like a milk crate or milk carton, you can cut the bottom up, put the top on. You can take that cap off and help kind of vent that and then put that cap on at night. But having a way that you can open it up and close it up so that during the day, if it it warms up quite a bit, you're not capturing too much heat, and then cooking your plants.
Chris Enroth:Yeah. Yeah. Even with these small little cloches, you you get into temperature management and that high temperatures can be an issue. If you you not only can you protect it from the cold, but you can cook them from from the sun. So, yep, gotta manage those temperatures and keep an eye on things.
Chris Enroth:That was that was the biggest part of when I, you know, did season extension. It was always watching the temperature, knowing if it was gonna be a sunny day or a cloudy day, and then checking the news to see if there were any reports of giant pieces of plastic flying across the highway because my high tunnel was destroyed in a windstorm or something. Those were always I woke up every morning, and I did that. So that that was my routine. Hey.
Chris Enroth:That's why I don't do it as much anymore. Oh goodness. Well but, Ken, there are way more things that we can do. I I would say probably one of the ones that most people do now, it it this does count as season extension, is some type of a floating row cover. And, by that, we mean you're just putting, like, a sheet over a garden bed.
Chris Enroth:And you would anchor it down, staple it down, or or weigh it down with something. And this can be something that I know a lot of us probably have lying around the house, a bed sheet. And, essentially, this is just fabric that is porous that, you know, you could usually, the way to do this is you would lift that bedsheet off of the the crop to expose the soil to the sunlight. The soil warms up. Then as the sun sets, you put the bed sheet back over, traps that heat closer to the ground, allows those plants to stay a little bit warmer than they would if unless they if that they were uncovered.
Chris Enroth:If you don't want to ruin your nice Egyptian linens and, you know, your 1,000 thread count sheets that we all, I'm sure, have, the yeah. Let's let's be honest. I got the dinosaur bed sheets here. So the the industry does have specific materials that commercial growers use. You can use this in the backyard, garden.
Chris Enroth:It's actually pretty convenient. It's called row cover. A lot of times, it's also called kind of by, like, the brand name. And so but but row cover is what you would be searching for. And what this is is it's really it's a poly spun fiber fabric.
Chris Enroth:Poly being plastics, you know, the fibers that, you can see the individual strands of fibers in there. And what it does is it is like the bedsheet. It is porous. It does allow water and air flow through it. It does allow some light through it, and there are different weights or grades of row cover that, you know, will allow more or less light.
Chris Enroth:Of course, the ones that allow more light don't offer as much insulate insulation. The ones that, are a bit more darkening, they are bit more, higher rated in in insulated value. So it kinda depends on the crop you're growing, how much protection you need depending on your geography, the type of weather that you get. So I like row cover. I got a big old roll of it in my garage.
Chris Enroth:I do deploy it every so often. I do try to save it when I can because being made of plastic fibers, I I don't want to, necessarily just trash it every time I use it. It's not like a single use thing. It's not like using paper towels or something. You know?
Chris Enroth:So they can be reused, and I try to reuse them as often as I can.
Ken Johnson:Yeah. With those and depending on where you buy them, they'll usually be, like, heavier. And some of those the heavier ones advertise down into the twenties. I think just depending on the type was it 2 to 6, maybe a little more degrees protection is what you can get. Some of the really light ones you can use even in the summer, for, like, insect protection.
Ken Johnson:So if you're growing cabbage or kalen or the brassicas, it's and you want to cover those. You don't have to worry about caterpillars. You can get some of these lighter ones, and keep your, your butterflies and moths off of it. Mhmm. Yeah.
Chris Enroth:That that's a good point. And that can even help you grow the cool season crops during the hotter months. Now we're kinda doing the opposite effect here where it's hotter outside, and we're using that row cover now as more of a shade cloth device, in those instances. And, also, hey. Keep some insects off too.
Chris Enroth:So, yeah, try to that that's why I say, you know, I, try to reuse some of these products as much as you can, especially when we talk about plastic, using plastic in the landscape. I try to minimize it as much as possible, but it's so hard now because lots of really nice products are made of plastic.
Ken Johnson:Yeah. Let me let me skip order on this and go to low tunnels next because low tunnels are basically just floating row cover with a frame.
Chris Enroth:Mhmm.
Ken Johnson:So you're you're graduating a little bit here and building a lot of times it's it's gonna be like a metal wire and you can buy these or you can make your own. It's just making little hoops, putting those in the ground and then putting your floating row cover over that that hoop, without you're capturing more air, in there. You're getting it up off the plants. Sometimes if it's resting on the plants that that cold can transfer a little bit easier through there. So it's ideally up off the plants.
Ken Johnson:You got a bigger area protecting more air mass in there, which which is gonna make it take it a little bit longer to cool off. You're not buying all kinds of time all kinds of heat, but maybe maybe a little bit extra.
Chris Enroth:Yep. You have that, you know, that increase of airspace, that insulation. That's that it does it does buy you a little bit more. I agree. And if people wanna know, I I I shutter to do this, but I could.
Chris Enroth:I did make a video about how to make your own low tunnel hoops. I shutter because it was many years ago, and I haven't watched that video in a long time. And I I probably be like, oh, boy. I don't know what I was talking about then. But but, yes, I will share a link to that below in in the, description about how to build your own low tunnel hoops.
Chris Enroth:I think I use, like, an actual, pipe bender that I bought, and you buy these benders based upon how wide of a garden bed that you have. You don't necessarily need to buy one of those pipe benders, though. You can there you can go online and also find other videos that show you how to make a jig for certain sizes of pipes and how how wide you want them. So, yeah, there's there's a lot of information about how to do this yourself, online. I'll link I'll link my very own video, below for that.
Ken Johnson:Yes. And and there are places that sell pre bent and everything too if you if you wanna spend a little extra money, but don't wanna deal with with doing it yourself.
Chris Enroth:Yes. Yep. Well, Ken, does that mean if we graduated from from, row cover to low tunnel, we need to now go right up into the high tunnel? What happened? Because there, yes, there are a few more things involved, but to me, a high tunnel is just a low tunnel blown up bigger.
Chris Enroth:It's really the same shape, same structure, whereas a low tunnel, you I guess you could crawl in it, but, normally, you just take the covering off and you you walk along it. The high tunnel, you walk into it, and you can stand up and you can, work in there, all while it's snowing around you. And I have done that, several times before. That's actually a lot of fun to do in the middle of winter. But a high tunnel is is essentially, again, just these metal conduit, that is bent in this hoop shape.
Chris Enroth:And, really, where we're at in Illinois, we have 2 choices in terms of our roof on these high tunnels. You can have a kind of a a quonset roof, which is just it's just rounded at the top, or you can have a a gothic peak roof, which a lot of people, at least in central and on up into Northern Illinois, will opt for because the peak of that roof allows snow to shed off more. And that is something which can help relieve snow load, which is something you have to think about, with these. And so, but, yes, your your roof lines can can vary, but it's essentially this metal pipe that is covered in a a poly plastic film. It's it's not the kind of plastic, though, you buy at the hardware center.
Chris Enroth:You know? This is not the drop cloth you use to keep paint off the carpet when you're painting. This is plastic that has been UV treated so that when it is exposed to sunlight, it does not just evaporate into nothing. Now a lot of our plastic at, you know, our drop cloths, things like that you buy at the paint store. I know a lot of people have used this before.
Chris Enroth:It barely lasts one winter. Exposure to that UV light, it just starts to degrade right away almost. And so something to be aware of. The other thing while while we're talking about degradation, and that is the use of PVC plastic piping instead of the metal conduit, there are some plastic films that chemically react when it comes in contact with PVC piping, and, it will actually, erode that. Where those tube meet, it will actually erode.
Chris Enroth:So that's why, a lot of times, I try to steer people away from the PVC plastic and more towards the metal, either wires for your low tunnels or metal, metal piping and definitely the metal piping for your, high tunnel.
Ken Johnson:I'm trying to think so. And so caterpillar tunnel would be similar to the high tunnel. It's just a little more a little less permanent, of a structure. And the other one we have here in Jackson, we've had that plastic. Was that 3 years now?
Ken Johnson:It's got some holes in it, but for the most part, it's it's holding up, pretty well. So you can you can use this for multiple years.
Chris Enroth:Mhmm. As far as I know, the lifespan of most high tunnel plastic is 7 years. After that a lot of times, it will still work, but it might get all cloudy and more opaque, which means you're getting less sunlight that moves in into the structure. So that that could do a couple things. 1, it can reduce the amount of heating that can occur.
Chris Enroth:Less sunlight getting in, the less light that gets converted to heat energy. You you don't heat as effectively. The other thing is your plants aren't getting as much light. So there are, you know, a a couple reasons why growers will often switch after about 7 years. It's where they they typically find that as as long as the, high tunnel plastic will last them.
Ken Johnson:Yeah. And then with, you know, with your your high tunnels, you can put a low tunnel within that or you can use your floating air cover. So you can, I guess, stack your season extension techniques here, with some of these bigger ones? So give you a little, maybe not tremendous amount more, but it'll give you a little bit more heat retention and protection, for your crops. And and when I think, you know, high tunnel gatapilliteron, those are a little more permanent structures.
Ken Johnson:So if you are gonna be doing this, if you've got that plastic on there, rainwater is not getting in. So you're gonna have to have some kind of irrigation or something in there, to keep those plants watered. Then some of the other one we have here. And in Jacksonville, We we don't have grow anything in it during the winter. And when you get out there in the spring, it is is very, very dry, in there.
Chris Enroth:Well, that and that's true. Like, a lot of things happen throughout the winter, including it's sunny out there, and it sort of bakes in there. There as I said before, temperature management is really important. On those sunny days in the winter, even if it's below freezing, I would have to go out, and I had a high tunnel, and I would have to lift the sides up to vent it to so that my plants on the inside would not, get too hot. And so you're it's it's you're really doing a lot of temperature management in the winter.
Chris Enroth:Unfortunately, I wouldn't have to water as much. You know, if the plants aren't growing as much, they're not using as much water. And so it it watering in the winter is not as critical inside of a a high tunnel, or even a low tunnel. And so that it wouldn't be as big of a problem in terms of water, but you seal that puppy up all winter long, you show up in the spring, that thing is it's like it's it's well done inside there.
Ken Johnson:Yeah. I got a probably, it was probably April sometime. We got a thermometer and put it out in ours, and we broke it. It got so hot in there. So hot.
Ken Johnson:It it did the it was a min max and did humidity. It was up over a 120 degrees. And then you open it up as I go open it in an oven, and close to a 100% humidity. Because we hadn't killed the grass in there yet. So it's all transpiring.
Ken Johnson:And it was it was intense going in there when it was all sealed up and and hadn't opened it up for for several days when it was nice sunny days.
Chris Enroth:Mhmm. Yeah. I I would say they are fun and comfortable to work in most days in the winter. When you're in the summer months and you're working in a high tunnel, even with the the end walls open and the sides up, you usually have to take breaks and go outside to cool off. Even if it's, like, 90 some degrees outside, it's still gonna be cooler outside than it is in the high tunnel.
Chris Enroth:And so, yeah. Growing in a high tunnel in the summer, there's a that's a whole other podcast, I think, that we could probably get into, but, the the temperature management is critical. And then water management. So, Ken, see, how many years has it have you had that caterpillar tunnel up? Has it been
Ken Johnson:3 years.
Chris Enroth:You say? So Yeah. One of the issues with prolonged covering of the soil by any structure and using, city water or, you know, potable water, not rainwater, essentially, is the buildup of, one, what you could have calcium deposits, things like that in your in your water, but also a lot of those fertilizers and these other things that you might be adding to the soil. A lot of times, this is a buildup of salts, and you wind up getting very salty soil. I visited, several high tunnels in the past, and sometimes there's this white film that develops on the top of the soil, and that's the salts that, that are starting to to develop there because they have not been exposed to the natural process of, like, rainwater falling down and pushing or pulling that salt down into the soil, that just sits there.
Ken Johnson:Yeah. And then we should probably see, you know, high tunnels, caterpillar tunnels is probably not something you're gonna do in your typical yard. This is more if you've got, I mean, you could. Could.
Chris Enroth:Yeah. But nothing's stopping you except for maybe city code or covenants or something.
Ken Johnson:Yeah. Yeah. It's it's probably something most people, are are not gonna be doing. And I'll see with our caterpillar tunnel, one that we take the plastic off in the summer, put the shade cloth on. So it's cool in there.
Ken Johnson:So we're for us, we're not having to worry about the solids and stuff because we can we're still getting that natural, rainfall and all that in there. Mhmm.
Chris Enroth:Did did we describe the difference between Caterpillar and high tunnel?
Ken Johnson:It's not as permanent.
Chris Enroth:Just not as permanent? Go go
Ken Johnson:into more detail if you want.
Chris Enroth:Yeah. I yes. I I guess maybe just the the thing is, like, Caterpillar, you know, kinda the name says it. You know? It it moves.
Chris Enroth:It can move. It is the the the posts of the frame are not as permanent. For, like, your caterpillar, Ken, it's just it's rebar that we've hammered into the ground, and then we slid a metal pipe over top of that. Then we could just pick it up and move it if we wanted to and put rebar in a different part, of the ground.
Ken Johnson:Yep. Whereas low tunnel is a little more. Mhmm. Or not low tunnel. High tunnel.
Chris Enroth:High high tunnel.
Ken Johnson:It was a little more a little more permanent.
Chris Enroth:Now there there are high tunnels that are built on rails,
Ken Johnson:and
Chris Enroth:they will roll them. And that helps to address some of the crop rotation issues, which I we haven't discussed, but also then addressing some of those salt buildup issues in those soils. It allows them to actually physically roll their high tunnel to a new growing area and allows the other one either to rest, grow a different crop, go follow, anything like that. So it it's in a perfect world, yeah, we'd we'd be have movable high tunnels, and we could let that soil take a break for a season or 2.
Ken Johnson:Do, greenhouses? Oh. Another one that's, again, probably not practical. For most people so greenhouses are this would be, like, your controlled environment agriculture. So with this, it's basically you can have a high tunnel to make a greenhouse, but you're automating you know, you've got heat you got heat sources main thing.
Ken Johnson:It's providing heat in some way. That's propane or wood burning stove or something like that. A lot of them will have ways to, you know, open and close automatically. You can do that. You can automate a lot more of this stuff.
Ken Johnson:So it's it's gonna cost a lot more, but it's also gonna take less of your time, to kinda manage. I mean, I still have to check it every once in a while and make sure it's working, and stuff. And these are definitely, permanent structures.
Chris Enroth:Yes. You are building a building. Usually, you're pouring a concrete pad. And and so, yeah, I I I would say the the major difference I usually tell people is what you described, Ken, is that it has an alternative heat source other than the sun. And I think it's usually the cost, which steers a lot of our our growers away from having an actual greenhouse.
Chris Enroth:Because if you think about what it takes to the cost of heating your home in the winter You know? Imagine the cost of heating a greenhouse and trying to grow a crop that you can then sell and make money on. Well, then that's gonna be some pretty expensive lettuce. So, because it takes a lot of fuel to keep things warm, you know, at least here in ill our part of Illinois in the winter. And so it's really that that heating cost that really keeps people away from greenhouses in particular, and a lot of folks really opt for more of those passive solar heating options, like high tunnels, low tunnels, floating row covers, clutches, all all those types of things.
Ken Johnson:Yeah. And I think typically with greenhouses, you know, if you're gonna be spending that money to heat it, people are probably getting supplemental lighting in there so you can grow, year round to kinda justify that cost, of building that and and keeping it heated and all of that.
Chris Enroth:I mean, it is a life goal of mine. I do want a greenhouse. When I was a kid, my grandma had a greenhouse that was attached to their home. That was it was, like, magical going in. There was, like, oranges.
Chris Enroth:There was a lime tree. There's all these kinda tropical fruits growing in Illinois. Ah, it it takes me back, to think about it. And then the you would she would open the the door of the greenhouse, and it would just smell like, citrus and plants in the wintertime. I it's a life goal of mine.
Chris Enroth:I'd love to have a detached greenhouse on my on my own house. But
Ken Johnson:We'll lean to a greenhouse.
Chris Enroth:Yep. Yeah. I'm trying to win that lottery. Trying. Yep.
Chris Enroth:Well, there there is one more season extension device, like a structure that we can use. I think that that that some homeowners, I've I've seen them definitely deploy in their yard, and that is using a cold frame, but which is really just it's essentially a box, and it's angled and that the the angle is facing the south. So, you know, as the sun gets lower in the sky in the winter months, we use that angle, to try to intercept as much sunlight as possible into this box with this kinda clear cover on it. Could be plastic hard plastic, you know, plastic film, could be glass, old reused windows, things like that. But, yeah, cold frame is something that that I have grown in a few times, and it's actually a lot of fun to grow in, you know, something small like this.
Chris Enroth:And, I think I have a few pictures that I can I'll send to you, Ken, to throw in right here. You know, we've grown turnips. We've grown bok choy. And we've grown kale, spinach, lots of different crops in our our cold frame. And it it's literally just it's it's like a it's like a wedge shaped box made out of cedarwood, and it's got a poly hard plastic clear lid on top that we open up.
Chris Enroth:So and we do have a little, heat kinda air vent register on the back so it can vent air, if it gets a little too hot in there. But, yeah, I I do like growing in my my cold frame.
Ken Johnson:So you use that primarily in the spring, or you use it in the fall too?
Chris Enroth:It's primarily in the fall. I I, that's that's what I prefer now. In the spring, it is more for hardening off seedlings or protecting them, of, like, our warm season stuff, our tomatoes, peppers, things like that. So they can go from the basement into the cold frame, bring them outside of the cold frame to even get some wind, get some direct sun exposure, put them back into that more sheltered cold frame, and that's how we can harden things off a little bit better. But, yeah, fall, just throw some turnip seeds in there.
Chris Enroth:Turnips at Thanksgiving, delicious. My favorite thing.
Ken Johnson:So have you ever, heard about people just using straw bales? Put Mhmm. Piece of plastic or something over that. Several years ago, we got a bunch of windows. That are from old house.
Ken Johnson:Pretty sure it's lead paint. So I was working on cleaning 1 up and, got almost done, and the glass broke and Oh. I got very angry and I haven't done the rest of the since. Because I spent so much time trying to get that paint off and scraping and heat gun and
Chris Enroth:No lead in the garden. Gotta keep it out. Oh, man. That stinks.
Ken Johnson:It it almost broke me. Well, I
Chris Enroth:think I maybe I can get you my I'm trying to think. Yeah. I might have one extra you can use. I'll have to go find it, though.
Ken Johnson:So I have, like, 4 more windows. I just
Chris Enroth:Mhmm.
Ken Johnson:The one experience scared me. One of these days, I'll go back to cleaning them up.
Chris Enroth:So the the and there's an additional strategy with cold frames, and that is where you can convert it into a a hot frame, or I think they also call it, like, a hotbed or something like that. And that is where you actually will bury some composting material. Could be, I guess, manures, could be yard waste leaves, grass clippings, things like that. It allows it to compost as it's buried sort of in the back that generates heat kind of artificial well, not artificially, I guess, more naturally, heats up that the interior of that structure. I've even seen people that will put a sand base down and put some heating coils underneath there.
Chris Enroth:That's more for the serious, gardener seed starter. A lot of people even use that to propagate, like, woody cuttings to, like, root cuttings in that type of situation. So, I think cold frames are really versatile, and, like I said, they can be built out of anything. So, you know, if you'd want it, dip your toe into pushing that season a little bit beyond what you normally grow, maybe a cold frame would be a good place to start.
Ken Johnson:Yeah. Could be the beginning of your greenhouse journey with your hot frame.
Chris Enroth:Exactly. Yes. Yes. If we all demand greenhouses, that that should lower the price. Right?
Chris Enroth:No. Is that how supply demand works? Oh, no. No. Only I get the greenhouse then.
Chris Enroth:Yes. Well, Kent, we also mentioned this, though. Like, this is a type of season extension. It's just starting your seeds inside. Just like you're gonna push that season a little bit earlier than if you just sewed everything direct into the ground.
Ken Johnson:Yeah. I mean, you figure with yeah. Especially your warm season stuff. I mean, you figure you're starting your tomatoes, well, depending on the person, 6 weeks early. So you're that's you know, you're getting a month and a half jump, just by starting that stuff inside of your feed.
Ken Johnson:To direct seed that tomato outside mid to late May, Maybe you're maybe you get some tomatoes depending on on the the culture where you're growing. So But then
Chris Enroth:you you would need season extension for the fall so
Ken Johnson:you could get a tomato. Yeah. Yeah. I think that's yeah. 1, Let's say a lot of people that garden are doing season extension.
Ken Johnson:They just don't realize it because we don't think of indoor seeds starting a season extension. Mhmm.
Chris Enroth:Yeah. No. I agree. Yeah. That is that is totally seeds a season extension.
Chris Enroth:You're you were have some type of an environment that you're protecting those plants, and and it gets you a jump on the the growing season. Yep.
Ken Johnson:Yeah. Or let's say grow stuff you wouldn't be able to otherwise grow because the season's too short.
Chris Enroth:Mhmm. That was a lot of great information about how we can push our growing season, whether we want to grow warmer season crops longer into the year or we want to start our cool season crops and grow them perhaps even throughout the winter. Well, the Good Growing Podcast is a production of University of Illinois Extension edited this week by Ken Johnson. Hey, Ken. Thank you so much for chatting about season extension with me today.
Chris Enroth:Appreciate seeing you. And I I guess it's gonna be cold soon. We'll get that frost eventually. But, yeah. Fingers crossed.
Chris Enroth:Yeah. Trying to kill our tomatoes here.
Ken Johnson:Maybe maybe someday, possibly. It's not once those tomatoes are out, I can start cleaning up those windows again. There you go. Spring.
Chris Enroth:I'll get you a paint scraper for Christmas.
Ken Johnson:And let's do this again next week.
Chris Enroth:Oh, we shall do this again next week. Hey, we got a couple garden bites headed your way. Cause we got all kinds of fun things coming up. We're gonna go see some poinsettias. We're gonna go, eat some turkey.
Chris Enroth:We're gonna have a great couple weeks coming up here at the end of November. So listeners, thank you for doing what you do best, and that is listening. Or if you're watching us on YouTube, watching. And as always, keep on growing. I'm still recording.
Chris Enroth:Well, there we go. And that now. Right.