Becky Sideman talks season extension and overwintering veggies, Emma Erler answers a question about winter sowing and frost seeding, and Nate Bernitz shares tips for putting the garden to bed.


Spinach in a high tunnel

 Play Episode 

No matter what scale you’re growing at, growing veggies later into the fall, and even through winter, may be easier than you think. There’s a spectrum of techniques, from using old sheets to installing a high tunnel and so much in between. Becky Sideman has spent years researching agricultural season extension and experimenting with season extension and overwintering strategies at a small scale, and shares those proven tips and solutions with us on this episode of Granite State Gardening.

  • Featured Question: Is winter sowing a shortcut to spring? 
  • Featured Plant: Lovage (Levisticum officinale
  • Closing Tip: Putting the garden to bed 




    Check out our Granite State Gardening Podcast homepage

    Transcript by

    Nate Bernitz  0:00  
    Welcome to the Granite State Gardening podcast, a production of the University of New Hampshire Cooperative Extension. Today's episode features a conversation between Becky Seidman and I on season extension and overwintering veggies in the garden and on the homestead. We'll also have a featured question by Emma Erler on winter sowing and frost seeding, and I'll share a few tips for putting the garden to bed at the end. As always, Emma will highlight a featured plant. Lots to get to today, so let's get into it.

    Greetings Granite State gardeners. I'm Nate Burnitz, Public Engagement Manager for UNH Extension. I'm joined now by UNH Extension Sustainable Horticulture Specialist Becky Seidman, who is also a researcher at the New Hampshire Agricultural Experiment Station, and a professor of Sustainable Agriculture and Food Systems in the Department of Biological Sciences at the University of New Hampshire. Now that we're already in early October, I know garlic is on your mind. But I wonder if you're done planting all your other veggies until spring, or if you still have some planting to do.

    Becky Sideman  1:12  
    I'm thinking mostly about garlic, although I do like my ornamental bulbs as well. I'm getting ready to plant some garlic for the winter. I'm also thinking about - everything's pretty much planted for late fall harvest, but keeping those going and keeping those protected from frosts that are coming is a big focus of my efforts right now.

    Well, that's very convenient, because that's what we're going to be talking about. Becky, tell us about your favorite garlic varieties.

    Oh, that's funny. We grow five garlic varieties at home, but even if I told you what they were, I'm a little suspicious that everyone's garlic varieties are not the same. Even ones with the same name, there's some varietal confusion. We grow ones that we purchased as Music, and Inchelium, and Russian Red and Russian top set. All of these I like because they're different. I think the diversity is good. Some of them do better in some years than others, and some are bigger in some years than others and so I like to keep all that diversity. But in reality, I can't really taste the difference between them.

    Nate Bernitz  2:33  
    Okay, so I'm actually only growing garlic for the second time now. The first time I did it, I was really excited about the variety I was going to get in the mail. At the very last minute, they pulled the curtain out from under me. They said that the garlic had some sort of nematode pest issue that they had screened for and caught and so they didn't fulfill my order. I ended up getting stuck with some sort of leftover garlic at the local feed store. I've basically grown up eating garlic from the grocery store. I'm ready for the next phase of my life where I grow delicious garlic varieties in my garden. I want to revisit this topic in three years, when I'm able to say what I've had, what I've grown myself, and what I like. Because I know I like garlic, I even like garlic raw, sometimes. The elephant garlic or something like that is delicious raw. I like garlic in everything. I can't wait to be able to answer that authoritatively, with experience under my belt - proudly beaming from all my success in the garlic department. Speaking of preferences,  Becky, from your experience, are there any veggies that you prefer to grow in the fall as opposed to the spring?

    Becky Sideman  3:55  
    There are very few crops that I prefer to seed in the fall because around here, most things need to get going at least mid-summer if we want to have them grow into the fall or be overwintered. An example that I can think of and this isn't quite what you asked, but when I think about strong preferences, I think about parsnip, which I've been thinking about for some time, because I plant my parsnips back in June, but I prefer to harvest those in the spring rather than the fall. So I want to protect them and keep them in place because they're much sweeter in the spring, of course. So that's an example where I think there's a really clear preference.

    Nate Bernitz  4:41  
    Well, let me let me explain what I'm thinking here. I know that some crops have a reputation for tasting better after they've experienced frost. And so if you're growing in the spring, you're planting or transplanting out in that frost period. But by the time you're harvesting and those crops are mature, we're past the time of frost, whereas in the fall, it's the complete opposite dynamic. So I'm thinking, are there any crops that just taste better when they're planted in, say the late summer and you're harvesting them after we've had some mild frosts?

    Becky Sideman  5:18  
    Yes. Let me amend my response. Yeah. What hung me up was this idea of planting in the fall. Many of our fall-harvested crops, as you mentioned, are planted a bit earlier than that, like in the late summer. But spinach, chard, beets, carrots, any of the brassicas like kale, or Brussel, sprouts, rutabagas, all of these are actually, in my opinion, better and sweeter and more flavorful if they're harvested after they've gotten a bit of a cold snap -  after that first frost. So I would say all of those actually benefit from that cold fall weather.

    Nate Bernitz  6:11  
    You mentioned first frost. How do you anticipate when that's going to be and how do you plan around that? If you pinpointed a certain date on the calendar as anticipating, hey, by this time, it's really likely we're going to have that first frost, how is that impacting your planning for your fall garden as well as any sort of protection that you might give crops out in your garden in anticipation of that first frost?

    Becky Sideman  6:37  
    Well, I would say that the first frost date is really most important, or frost at all. Frost is most important when you're thinking about trying to protect sensitive crops, like warm season crops, like peppers, and eggplants, and tomatoes, and so forth. When you're talking about scheduling and planting cool season vegetables, really, the first frost date is not important. What's important is that they've gotten a fair amount of growth before the light levels and the temperature generally go down. The first frost date isn't really critical to keep in mind for a fall or winter garden, it's really when the ground freezes, and when the temperature drops, generally. So really, we're talking about planting stuff, often in August, or very early September at the latest, so that it has enough time to grow before we just don't get warm days anymore. But these kinds of crops are resistant to - they're cold/hot tolerant, they can take a frost, so that the frost itself is not key. It's the weather around the fall. As far as predicting, it's really, really hard. You can look up frost date calendars, and try to predict for your area, but it's much more variable, than I think we tend to expect for spring for us. And it seems to be pushing later often. It's quite difficult to predict. It could be anywhere from four to six weeks different from one year to another. And so I think the real key there is to think about being ready for it so that you're ready to protect the things that are going to die when the frost comes. But it's not necessarily so so important when you're talking about these fall and winter crops.

    Nate Bernitz  8:46  
    The two takeaways there: one is that the first frost of the fall is a lot more unpredictable than the last frost of the spring, and the second is that it's less important from a gardening perspective. There are some warm season crops that we do stretch as late as we can like tomatoes, where I know some people might be really motivated to keep those tomatoes going even longer, and might throw row cover or something like that over their tomatoes. So keeping an eye on the forecast in that regard. It doesn't really require any planning though. If you know that a frost is coming, maybe tomorrow morning, you just go out there and throw some row cover on and hope for the best.

    Becky Sideman  9:29  
    That's really true. It depends on the volume of your gardening efforts. How much planning this requires.

    Nate Bernitz  9:37  
    Say more about that, because I'm thinking about myself being a really small-scale gardener, but for someone who is growing at a larger scale and can't just walk outside, throw some row cover on and come back in. What sort of planning is going into that? Now we're thinking about homesteader-scale, potentially.

    Becky Sideman  9:58  
    Well, exactly. And If you are a serious homesteader you probably have a supply of lots of old blankets and sheets and extra thick row covers and things at the ready to cover over your plants. You've probably thought about the fact that, gosh, some of these are going to get crushed if I just cover them with a blanket, I need to build some kind of structure to support them. You have maybe thought about which crops ahead of time, you're going to be covering, so that you don't remember in the morning that whoops, I forgot that whole plot. Maybe that's getting a little excessive. But if you have many production areas and lots of crops, it's good to think that through and make sure you have the supplies you need to cover them if you're going to cover them. Or, harvest those crops and bring them in, if they're close enough to the end of the season that it's not worth keeping them going.

    Nate Bernitz  11:02  
    I think as we go through this conversation, it's going to be good to keep our mind on whether something is practical for a certain type of gardener. Really enterprising gardeners might have an unheated greenhouse, might even have a high tunnel. But for many gardeners, they may be thinking more about investing or building their first cold frame, or potentially setting up a low tunnel for the first time or utilizing row cover. So I want to keep this spectrum in mind, as we start to talk about season extension. Becky, this is kind of a core expertise of yours, something you've done a lot of research on in an agricultural context. But I know it's also something that you practice and employ as an enthusiastic gardener yourself. So I mentioned some different techniques: low tunnels, row cover, cold frames, high tunnels, unheated greenhouses. Does that kind of cover the gamut of season extension techniques that we should talk about, or am I missing anything?

    Becky Sideman  12:13  
    I think it does. I think I would add one little thing to it, and that's if you are thinking about a couple of unusual alternative crops. I'm thinking of radicchios, I'm thinking about Belgian endives, these are things where you grow them through the main season, but you dig them up, pop those roots, and then move them into a dark part of your basement or your house and continue to grow those. So there's something where you've got some season extension, you're producing some salad vegetables without even being in the garden. You brought the garden inside.

    Nate Bernitz  12:55  
    Wow, that's really neat, I had no idea. I'll have to cultivate a palate for Belgian endives and get that going. That sounds great. I feel like row cover is the easiest entry point. That's something that you might already have on hand from spring gardening, it's something that you might be using for insect exclusion or frost protection for tender crops in the late spring. So how can that be a tool for the fall? And what kind of impact might you expect? Is that really going to make a marginal difference? Or could that actually make a pretty significant difference? And what crops are you thinking are really good candidates to be looking at using row cover for?

    Becky Sideman  13:44  
    It's a great question, I think that row covers can be used pretty much for any crop, and that you're right, they're the lowest entry point - very easy to get, very easy to use. They will make a very big difference in terms of keeping a frost-sensitive crop alive if they're layered up enough and it doesn't get too cold. So it could mean that you have access to some frost-sensitive crops for another couple of weeks, three weeks, four weeks if we get an early frost, and then there's a big gap before the next one, for example, or before the hard freeze. I would say in terms of stimulating and promoting fall growth on cold-tolerant crops, there's probably limited gain from row cover. You will get a little bit and plants will to grow faster, they'll have more growing degree days, they will get bigger. You probably would get some some gain from that. You would get more gain if you put them on a hoop and therefore have some sort of air buffered around them, and if you also cover them with plastic so as to try to create a low tunnel. So you canstart to increase the effects a little bit by adding other materials to make something that's actually closer to a greenhouse, really.

    Nate Bernitz  15:20  
    Before we get into low tunnels, I want to go back to one thing you said, you mentioned a hard freeze. Can you help me and listeners understand what is the distinction between a frost and a hard freeze?

    Becky Sideman  15:35  
    Frost happens anytime the temperature drops to 32 degrees Fahrenheit or below, and cold-sensitive crops like sweet potatoes or peppers and things like that will be damaged by exposure to that temperature. But often, if it just gets to 32 degrees for a few hours, the plants might not be hurt very badly, maybe a few leaves would be injured, but the growing point survives and the plant can come out of that. A hard freeze is when the temperatures go down into, I don't know if there's a specific cut off or that terminology, but I would say the low 20s. That whole period of time when the temperatures are dropping to the low 20s, it's below 32 for a long period of time. So there's a much better chance that plants are injured or killed, even if they're covered, because of the prolonged exposure to below freezing temperatures. So when we talk about a light frost or a harder frost, you can often protect plants. But when we start talking about these much colder temperatures, a hard freeze, we might actually lose plants.

    Nate Bernitz  17:02  
    I imagine that even for plants that are hardy enough to withstand a hard freeze, their rate of growth would probably drop precipitously, right?

    Becky Sideman  17:14  
    Yes, although a lot of rate of growth has to do with the environmental conditions around that period of time. So usually by the time we've hit a hard freeze, the general daytime highs and lows have gradually dropped off to a point where we're not above the base temperature for the plant - the temperature at which the plant can grow. We're not above that base temperature for very much time in a day. If we had a hard freeze, all of a sudden out of the blue in August, and then we continue to have perfectly good weather, it wouldn't probably affect the rate of growth as long as you could keep things alive. Because the rate of growth is more determined about how many hours a day you're above that base temperature, basically.

    Nate Bernitz  18:11  
    You talked about low tunnels in the context of row cover. Because if you set up a frame, and I guess that frame could be made of PVC, it could be made of galvanized wire, any sort of thing that is creating a hoop structure, you can have row cover on that, which is going to entail stretching that row cover over and having something weighing it down on either side. But what you're saying is when it gets really cold as we transition from fall into winter, if you actually want to keep using that you need to switch from row cover to some sort of thick plastic. Is that right?

    Becky Sideman  18:52  
    Yeah, I mean, you can keep using it as row cover, but you just have to accept that row covers are fabrics, and it allows air transfer. So what you're doing with that row cover is you are basically protecting an area of warm air and warm soil around the plant and you are slowing down that air transfer with the rest of the environment and the cold air that's everywhere else. Because it's porous, those temperatures are going to equilibrate eventually. So if you have something similarly in the daytime when it warms up, those temperatures are equilibrating because air is moving. When you have something like plastic that's less permeable, it builds up higher temperatures because that air is not moving throughout the day and therefore you get higher temperatures going into the evening when it's cooling off. So that also is not going to keep you warm and cozy through the whole winter. When it gets cold enough, it won't do the trick. But it's more protective in terms of its more warming than row cover alone.

    Nate Bernitz  20:12  
    So what crops in a vegetable garden would you say are great candidates to consider growing under a low tunnel? Can you actually expect those crops to continue to grow where you can get continual harvest throughout the winter? Where should we be setting our expectations?

    Becky Sideman  20:34  
    I think this depends a little bit on where you're located. If you're way up in northern New Hampshire, you should keep your expectations lower, because it's going to get colder faster, and you may get snow fall and the ground may freeze. So practically speaking, even if you can get crops to grow later into the fall, you won't be able to access them easily in a low tunnel, because you won't be able to easily move those covers and get in there. So I would say that harvesting into the fall is a reasonable expectation. You might expect to do that into maybe Christmas time or January 1, if you were in southern New Hampshire. You might be looking at November 1 if you are way up near the Canadian border. There's different expectations there. From my research, one of the most exciting things about low tunnels and a vegetable garden is that they are this semi-protected environment where you can plant crops that will overwinter in those tunnels, where you're not actually harvesting them in the fall, they're just protected there. You can harvest them in the spring when the snow is finally gone. It gets you kind of a jump on the spring. Candidate crops for that kind of system include kale, and spinach, and onions and scallions. Things like that, which are cold hardy, but we don't think of them as surviving our typical unprotected winters, but they would survive under a low tunnel just fine.

    Nate Bernitz  22:23  
    If you're intending to overwinter something like a scallion, or kale or spinach, when are you actually planting that out in your garden?

    Becky Sideman  22:34  
    The timing of planting is tricky. It's tricky because every fall's weather looks different. But realistically, you're probably looking at planting that early enough so that the plant can get established before the winter comes. So it's got to put on some growth ahead of time. You're probably looking at sometime in the month of September. If you were looking at onions and scallions that you were going to start from seed, you'd probably be seeding them in August, and then planting them out in September or very early October. All of this varies enormously based on where you are, how warm your falls are, and the kinds of varieties you're looking at. These are the kinds of questions I've spent lots of time trying to tease out in my research. It's always trade-offs between planting early and planting late, and how well they survive versus how much time it takes, and whether they possibly get too big before winter comes. This is definitely gardening 201,  this is not gardening 101 when you're starting to look at these overwintering systems.

    Nate Bernitz  23:56  
    If you're intending to overwinter something like spinach, could you potentially plant it in early September and actually get a harvest or two and then decide, hey, I'm gonna try and overwinter this and keep harvesting in the spring? Or is it a situation where you really need to plant it with the sole intention of overwintering it and doing all your harvesting in the spring?

    Becky Sideman  24:21  
    You're absolutely right, you can do that. And in fact, our work with that here in Durham showed that you get the most spinach off plants that are planted earlier that you harvest through the fall. Then they take sort of a break during the winter and then you harvest again in the spring. Yeah, that is absolutely possible.

    Nate Bernitz  24:46  
    We've talked about some greens, some of these colder hardy greens, so I'm curious about something like lettuce that is not as cold hardy but is a tasty green and we know that at least in commercial agriculture winter lettuce is a great crop that I love to buy. There are also some of the brassicas that I'm curious about as well. Are low tunnels appropriate for overwintering lettuce and some of the brassicas, or do you need to step it up a notch to a different overwintering technique?

    Becky Sideman  25:21  
    I would say that, in general, the brassica family crops are more cold tolerant than lettuce. So they are a better candidate for overwintering in low tunnels than lettuce. That said, not all of them are very cold tolerant, and not all of them will survive a typical winter in a low tunnel. We have had years when we're doing research here, when lettuce grown in low tunnels into the fall, could be harvested until sometime in January. But there's been other years when it's died much earlier than that, because of sudden cold spells. So it's more risky. As you get with like slightly less hardy crops, it gets riskier, and there's a higher chance of it perishing due to cold damage. If you wanted to really guarantee your ability to overwinter crops like that, you would have to scale it up. You'd have to look at a high tunnel and high tunnels in combination with row covers if you weren't going to heat your high tunnel. But many of the commercial growers that look at wintergreen production in this state do heat minimally, because that removes the risk of the crop having cold damage or dying due to some sudden cold period. Then we're talking about much much, much bigger events. But even with an unheated high tunnel, it's reasonable to expect many mixed greens, including lettuces through much of the year, especially in the southern part of the state.

    Nate Bernitz  27:15  
    Can you actually tell us what a high tunnel is? Is there some small version of a high tunnel that is practical for someone at a garden scale?

    Becky Sideman  27:27  
    I think so, but I also come at this from a homesteader perspective where lots of things are practical that might not be for other people. A high tunnel is basically an unheated greenhouse. There are several manufacturers and they're made of sort of Gothic pointed bows, so that they shed snow. Those bows come in various widths. You asked about size; a gardener could put up a high tunnel that is 12 feet wide and 14 feet long, which is not a very big footprint, but still a protected environment that you can walk in and access in the winter months, and really have a lot of productivity from. Our tunnel at home is a little bigger than that. It's about 20 feet wide and about 40 feet long. And that's even more protected space and more warm because it's bigger. The sky is the limit on these things. But I do think that they are practical. If gardening is your focus and growing local food year-round is your focus, that is probably the most sure way to be able to do that.

    Nate Bernitz  28:56  
    What kind of investment are we looking at to get in at that low end of the high tunnel size? Are we looking at anticipating a few hundred dollars?  What does your experience tell you?

    Becky Sideman  29:14  
    My feeling is that for a smaller-sized, home size high tunnel, you'd probably be looking more at I'm guessing a thousand dollars or a little more. What this is getting is something that is rugged and is going to withstand snow loads. You can do it much more inexpensively with various ways that are not going to necessarily withstand storms and heavy snow. I'm talking about a a rugged, built-for-our-conditions kind of structure that will stand and be there for the foreseeable future. With these, usually, you you buy the bows and the framing. You fabricate yourselves the end walls, and you have to buy a piece of plastic to cover it. Those are kind of the basic pieces that go into that.

    Nate Bernitz  30:22  
    Going back to low tunnels for a second, are they designed potentially to also shed snow? Or is that a real concern that they could just collapse under the weight of snow?

    Becky Sideman  30:32  
    You know, it's interesting. They're not designed to shed snow. Usually, they're just made out of rounded pieces of PVC, or conduit or something like that. One of the things when I started working with these for research is I was actually worried they might collapse under snow. They never did, even in years where we got tons of snow and ice, they never did. They collapsed in the spring when it became muddy out and the bows were not supported in the ground anymore. Then they would fall over. But they never collapsed under snow loads, interestingly.

    Nate Bernitz  31:17  
    How do you explain that? And for those really surprisingly tough low tunnels, what were you making them out of?

    Becky Sideman  31:24  
    Oh, well, I made them out of different things, because I was exploring that. We made them out of pieces of PVC that we would bend, 10 foot pieces of PVC pipe that we would bend and slip over little pieces of rebar that acted as ground posts in the ground. Those are some of them. Some of them were made out of bent, EMT conduit metal metal tubing. Both of these worked just fine. I attribute it to - there's not a lot of wind load on a low tunnel when there's a lot of snow. So the snow just comes up around it, and then keeps building up on top of it. But there just wasn't a lot of pressure on it, I guess. They just never collapsed. I would not expect the same thing for a greenhouse.

    Nate Bernitz  32:19  
    That's because of the wind on top of this now.

    Becky Sideman  32:23  
    You need to have an engineer on your program to ask them this question. But I am not sure.

    Nate Bernitz  32:30  
    Going really really far away from anything involving an engineer, I was hanging out with a few Master Gardeners this morning, and one of them said that she's had a lot of success overwintering in her garden by just piling straw on top of certain crops. So as the opposite of engineering there, what's your take on just piling mulch on say spinach, or something else?

    Becky Sideman  32:57  
    Straw and mulch are fabulous insulators. This is a really great way to overwinter. We do this with garlic, even though perhaps it doesn't need it. But with other more sensitive bulbs and things like that; we do this over parsnips or carrots sometimes to try to make it so the ground doesn't freeze solid when we want to go and harvest them. I've seen mixed results about when research has tried to compare straw versus low tunnels or other ways to protect actively growing green crops. It's insulating, but it also totally blocks light. I would not argue with the Master Gardener that you were speaking with who has had success, because if they have a system that works, I am sure they figured out there must be something about this that works. But at the same time, oftentimes when you cover a green, actively growing plant with, or not that actively growing but a green plant with straw, it will when it's warm enough start wanting to grow in the spring when the soil warms up. It may suffer from that. So there's some risks there. There's also the risk that it's a fabulous global habitat, which is also true for low tunnels I might add. Interestingly last year, we did a little experiment looking at row covers and straw mulch and their ability to protect an oat cover crop that was not to keep the oats growing, but it was there as an indicator, and all the oats were killed under the straw. There was a ton of predation happening. Lots of critters were under there eating things. So I think it could work but there's also some some risks with that as well, I guess I would say.

    Nate Bernitz  35:05  
    I will say another gardener who was in this conversation said that they also tried overwintering with straw, but when they took the straw up the plants came up with it. So another potential challenge.

    Becky Sideman  35:18  
    There's another possible pitfall.

    Nate Bernitz  35:21  
    You brought up carrots, Becky, and carrots are one of those crops that some people seem to have effortless success with, and other people seem to struggle, no matter what they try. Is it possible to grow carrots over the winter, overwinter carrots? Share your secrets on that one.

    Becky Sideman  35:38  
    I will be honest and tell you that I do not try to maintain carrots over winter outdoors. I keep them in a high tunnel. They do fabulously over winter in a high tunnel, harvesting through to about February when they start trying to grow again. The thing with carrots is that they are unlike parsnips, they're just a bit more cold-sensitive. So if we have luck  and a really mild winter, and everything's in our favor, it's possible to overwinter carrots successfully. That's why we can do it in a high tunnel, which is a bit warmer than outside. But given our typical weather conditions, I would not expect high chances of success in a given year with carrots outdoors without some supplemental protection. So I don't have a secret.

    Well, if you are going to try and do that with carrots, when would you look to plant those?

    You'd probably be looking to plant those in July or possibly a little bit earlier. That's the timing for if you are going to overwinter them in a high tunnel here. You would want them pretty big and grown by the time fall comes around and they stopped growing. So that's usually a July planting for high tunnel.

    Nate Bernitz  37:14  
    So your idea for a high tunnel, let me just make sure I understand what you're saying. So you plant in July, by the time you get to late fall, they're pretty well and grown. And you are continuously harvesting them through December, January, February. Then you mentioned that you there's kind of a cut off, where they start to grow again. Can you explain what you mean by that and why that's a problem, potentially?

    Becky Sideman  37:45  
    Carrots are a biennial. So the carrots are doing what carrots would do in the wild. They've grown, they've made this nice taproot. And if we don't harvest it, they overwinter in a mild climate. Then when that winter is done, and they start to perceive that it's getting longer days and warmer, they start to send out fine roots, feeder roots from that main tap root. And they start to grow. They will make a flower stock and they will go to flower, and it'll look just like a Queen Anne's lace - a wild carrot. So that's what they want to do and what they are doing. And as they send out those fibery feeding roots in the spring, they become less sweet and delicious and moretough and woody, and the flavor becomes more bitter and not delicious anymore. So when we notice they start to make those fine fibery roots, we pull them out very quickly and put them in the fridge or eat them all.

    Nate Bernitz  38:55  
    Carrots are one of those crops that are known for getting that winter sweetening, or they just get better and better in that sort of scenario, right?

    Becky Sideman  39:06  
    Incredibly sweet in the winter. Absolutely.

    Nate Bernitz  39:09  
    And we throw turnips and beets in there, just real quick, when are you planting turnips and beets for the same purpose?

    Becky Sideman  39:17  
    About the same time. Although turnips store so well in a root cellar that I would grow them outside and not mess around with high tunnel space. Plant them in July and then harvest them right before the ground freezes and put them in a root cellar.

    Nate Bernitz  39:39  
    Another challenging crop for for many gardeners are brussel sprouts. Is there any potential for growing brussel sprouts into winter, overwintering them?

    Becky Sideman  39:48  
    I don't think so. The reason is that I think that even though there are cold hardier, brussel sprouts, some are cold hardier than others, I think that the minimum cold temperatures we get are cold enough that they will eventually damage the brussel sprouts and reduce their quality. Really, when you get down into the teens, they really can't recover from that, and then they will decay and so forth. So I don't think there's a lot of potential for overwintering brussel sprouts. I think you're better off growing those into the fall. Believe it or not, if you have a decent root cellar storage space, they can be stored on the stalk in buckets of water. Not unlike a big giant bouquet of brussel sprouts, they can be stored reasonably well for several weeks, a couple few months. They do decrease in quality, but it's better than trying to keep them outside.

    Nate Bernitz  41:05  
    Do you have any experience growing in cold frames? I know that's a real small-scale enterprise. But that is an entry level opportunity for gardeners, especially those who have pretty limited space.

    Becky Sideman  41:22  
    I totally agree. I just don't have any experience growing in cold frames. I have this idea that they require a lot of management to keep the temperature in the ideal range, but they offer a lot of the benefits that a high tunnel would just on a smaller scale.

    Nate Bernitz  41:48  
    When I was thinking about cold frames, just in preparation for this conversation, as I often do, I went on to some websites that sell gardening supplies. I also went on to general websites like Amazon and those places just to see like, hey, what's even for sale. And there is a huge range of products. Some of them are really, really inexpensive and made with really thin plastic. Then other ones are sturdier and made with much thicker materials. I have to say I've heard some anecdotal experience from the really cheap ones, that they just don't stand up to the elements in our region and might be more appropriate for for further south. I want to be charitable, so I won't say that they're just products that you shouldn't buy in general, but they don't seem to work really well up here. Some people make their own out of old windows and things like that. I've also heard of people actually making what I've heard called hot beds, where you use some sort of electric heat source essentially, like a heat mat inside. It seems like a lot of work to me for a relatively little gain. But it's interesting. I've even heard of utilizing manure as a potential heat source. Again, I feel like I would need an engineer to explain that to me. Okay, Becky's taken off and now I'm going to turn it over to horticulturist and UNH Extension Field Specialist Emma Erler to answer this episode's featured question.

    Emma Erler  43:39  
    Is winter sowing a shortcut to spring? That's this episode's featured question. Some gardeners have found that winter sowing cool season annuals and vegetables in protected plastic jugs or other transparent cover containers can give them a slight jump on producing seedlings for spring. If you want to try winter sowing, start saving clear plastic containers like juice bottles. Fill the container partway with moist potting mix. Sow your seeds, and then place the containers in a cold but protected location. If you do this in February to March, seeds of cold tolerant crops such as beets, chard and cabbage will be ready to germinate as soon as soil temperatures reach minimum suitable levels, around 35 to 40 degrees Fahrenheit. Like a mini-greenhouse, the transparent covers capture solar energy that warms the soil or medium in the containers earlier than exposed soil in the ground in the spring. Be sure to provide slits or holes for ventilation to avoid overheating on sunny days and holes in the bottom of containers for drainage. Once you have vigorous seedlings, transplant them as soon as possible. Midwinter sowing or seeding also allows for natural stratification to occur. That is, exposing seeds to cold, moist conditions needed by many perennials and some annuals to break seed dormancy. For many herbaceous perennials and woody plant species, 60 to 90 days of cold temperatures in the 32 to 50 degree range are required, but some plants have more specific requirements. Seed companies are often a good source of specific information. You can moist stratify seeds in your refrigerator instead of winter sowing or seeding, too. Mix seeds with a small amount of moist, not wet, sand, vermiculite or sphagnum peat and a plastic bag or covered container. Label it and leave it to chill until spring. Once the seed has been stratified, it should be planted before it germinates. So if you gardeners out there want a shortcut the spring, winter sowing or seeding might do the trick, but be sure to choose appropriate species and pay attention to timing and other details.

    Nate Bernitz  45:58  
    Emma, what's this episode's featured plant?

    Emma Erler  46:02  
    The plant I want to feature this episode is Lovage, Levisticum officinale. Lovage is a perennial culinary herb that is often grown in herb and vegetable gardens for the celery-like flavor of its leaves, stems, roots and seeds. Celery can be a tricky plant to grow in New Hampshire. And I found that Lovage is a great alternative. It's dramatic in the garden, growing three to six feet tall, with deeply divided dark green leaves that are similar looking to parsley or celery leaves. And its flowers appear in the spring, yellow and flat-topped like other members of the varrot family, Apiaceae. Lovage is often used in soup, salad, sauces, stews, or really any other dish that can benefit from celery flavoring. The leaves are most often used, but the stems can be cooked as a vegetable, too. Lovage stems are hollow, which can make them fun to add to drinks like Bloody Marys. Also note that lovage has ornamental value and can look great at the back of a perennial border. If you have moist loamy soil and full sun, give Lovage a try.

    Nate Bernitz  47:14  
    Thanks Emma. As this episode comes to an end, I want to share some closing tips on putting the garden to bed. When I talked with Becky we touched on planning for frost and the fact that some veggies can handle light frost while others cannot. But at some point the garden must be put to bed. When you do, remove plants by cutting them down at the base, leaving the roots in the soil to break down. Also remove fallen leaves and fruits, composting healthy plant material and discarding diseased plant material. Fall can be a good time to add amendments like manure and lime if your soil needs it. Fall is likewise an excellent time of year for soil testing. If you're able to get them seeded by mid-September, cover crops like spring oats are an inexpensive option that will winter kill, but add organic matter and hold soil in place, among other benefits. And if you don't sow a cover crop consider spreading an organic mulch like straw to suppress weeds and protect the soil to reduce erosion and nutrient leaching. Speaking of weeds, fall is an important time to remove leftover mature weeds and control winter annual weeds that come up in the fall. Removing weeds now helps manage next year's weeds. Lastly, there's the decision of whether to till. Many gardeners till in the fall as standard practice, but if you're not incorporating soil amendments like manure and lime, you can actually bypass tillage and avoid the soil disturbance that comes along with it. In your perennial garden beds wait to cut back perennials until the foliage has died back, or wait until spring, just removing and discarding disease top growth in the fall while leaving healthy seed heads standing as a food source for birds. Moreover, dried stalks and leaves add winter interest to your garden, so consider waiting until early spring to do some of the cleanup you might have historically done in the fall. Fallen leaves can simply be left in perennial beds, around trees and shrubs, and on the periphery of your property. In your lawn, you're going to want to either rake up the leaves or use a mulching mower to chop them up in the yard where they will just decompose over time without smothering your grass. If you rake up the leaves, add them to your compost pile and save some leaves in a pile or in leaf bags so you have a good brown material to tap into for your compost pile over the winter and throughout next year's growing season. You can also save leaves to use as a garden mulch and the more you chop them up, the more valuable they will be. And that's your closing gardening tip.

    Thanks for tuning into this episode of Granite State Gardening. Until next time, make some plans to overwinter or extend the season in a new way this fall Granite State gardeners. Talk with you soon. Granite State Gardening is a production of University of New Hampshire Cooperative Extension, an equal opportunity educator and employer. Views expressed on this podcast are not necessarily those of the University, its trustees, or its volunteers. Inclusion or exclusion of commercial products and this podcast does not imply endorsement. The University of New Hampshire, US Department of Agriculture and New Hampshire counties cooperate to provide Extension programming in the Granite State. Learn more at

    Transcribed by Transcript edited by Rebecca Dube.



    Extension Field Specialist, Community & Economic Development
    Phone: (603) 678-4576
    Office: Cooperative Extension, Nesmith Hall Room 204, Durham, NH 03824