microgreens to baby-leaf to full-size heads: mastering lettuce, with tom stearns

I DON’T WANT my salad delivered in a plastic box or to pay a ransom price per pound either, meaning I want to produce homegrown as many months of the year as I can. Today’s topic is how to plant for the best salad year ever with organic seedsman Tom Stearns to guide us, as I kick off my annual Seed Series on the radio program and podcast.

Tom Stearns is founder of High Mowing Organic Seeds in Vermont, with more than 20 years specializing in breeding, selecting and marketing of organic varieties. From microgreens indoors to baby-leaf to mini-heads and up to full-sized heads in the garden, we talked about timing, spacing and making lettuce happy—even which types hold up best in the heat (and ways to help all lettuce do better when summer arrives).

Read along as you listen to the Jan. 14, 2019 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

success with lettuce, with tom stearns



Q. Over the years on the show you and I have talked about tomato hygiene, as you taught me to think of it, and spinach growing, and cucurbits and all kind of things—things that have proven to be really popular how-to’s that people are using again and again each year and searching, people finding them by search on the web. So I’m excited to get your advice on this most important topic of filling a salad bowl.

A. Yes, sure.

Q. I’ve been gardening, I don’t know, 100 years or so. [Laughter.] Well, 30-something … I don’t know, how long have I been gardening? For 35 years; something like that. And I feel like things have changed. You know, I used to get a couple of varieties of lettuce, ‘Black-Seeded Simpson’ and one of the oakleaf types, a couple of things, and I’d sow a block every week or two. I used to do blocks in the old days, and do cut and come again. But now, it’s like, wow. There are so many strategies and so many possibilities to really do a better job. So much choice. And I wondered if you could just characterize what’s going on, because you’ve been there at the pulse of it.

A. Well, I think a lot of it has to do with the versatility of this crop. When you think about it in as far as the kitchen is concerned, everybody knows what to do with lettuce. You don’t do much with it; you mix it into a bowl, you put some dressing on it and maybe put some cucumbers or cherry tomatoes or whatever on it. It’s totally un-intimidating, and it’s something that people eat as a regular part of a meal as opposed to, say, something like a fancy variety of winter squash or something like that.

Salad is ubiquitous and versatile, and so everybody who’s involved in the marketing of produce has known that and has stretched the use of salad, and what counts as salad, into a lot of different ways, and then that’s translated onto the farm and growers. And I think the big advantage for both gardeners and farmers in growing lettuce and other types of greens is that they are really quick.

All you need to do is to make a leaf. You don’t need to make a stalk, flower, fruit, none of that stuff. So, it’s really versatile in that way, too, and of course there are really interesting trends and things like you spoke about, about the diversity out there. It’s really different than it was even 10 years ago and certainly 20 or 30 years ago.

Q. Well, and if I were writing a story about lettuce as a garden writer in the newspaper years ago, or whatever, in a magazine, I would say: There are four basic types of lettuce. There’s the loose leafs, and there’s the crispheads and there’s the butterheads and there’s the cos or romaine. And now we have the celtuce or whatever, the stem lettuce. But anyway, now it’s like, in the [lettuce] category in a catalog like High Mowing, there’s a lot of different categories that didn’t even exist, having to do with the utility and what you get.

So, everyone loves baby-sized leaves, and Margaret’s old-style way again was that sort of cut and come again: sow it, broadcast it in a thickish way and cut the baby leaves a few times and then sow again, sow another block. But now, it’s different, so what about that, that sort of baby-leaf passion that people have?

A. Well, this is something that I don’t honestly know where it started and how much of this is coming from any European influence or not. But I’m assuming there were some early growers who 20-plus years ago on the West Coast started sowing very thickly, and basically mowing their crop of single leaves and not “wasting time” growing a full plant. Just using this crop to grow as a baby leaf, and maybe they’d get a second or third cut or maybe they wouldn’t.

But California discovered this, and now it’s so much more common to see a plastic box or clamshell of baby leaf, whether it’s lettuce or spinach or chard or kale more recently. And to see those fields in California, most of the lettuce for the country has been grown in California for a long time, and so the baby leaf has replaced a lot of the full head, full-size head lettuce. And then more recently, you’ve got these individual heads are coming back but they’re miniature heads.

Q. Yes, that’s a crazy thing. And I saw the original … Initially I saw Salanova was one breeding line and I think you have Eazyleaf with a Z in the middle. I’m sure there are other ones; I don’t know all of them. What is that? How does that work?

A. Well, even prior to the one cut Salanova and Eazyleaf types were these miniature romaines [above], like these ones that basically it’s like, you split it in half and it’s got a … you’ve two servings there ready to go. So these mini-heads, ‘Little Gem’ and mini-romaines and all the variations known.

Like you said, it’s so much more than the four types of lettuce. They’re crossing them with each other and coming up with different combinations and there’s colors and leaf types, like the edges being ruffled or folded or blistered, or all of that stuff. So yes, these miniature heads are something that we’ve really seen take off a lot. So, there’s that and then we can talk about the Eazyleaf, too, but these mini heads offer a crop of a full-sized head. Not a baby leaf but a full head within about two-thirds of the time that it would take to grow a regular full-sized head, and in half the space or less than half the space.

So, from a gardener or a farmer’s perspective you can pack a lot in and get it quicker and from an eater’s perspective, sometimes it seems maybe there’s even a little, not a backlash exactly, but the idea in the spring of having a head of lettuce to bite into or to work with as opposed to a bunch of tiny little baby leaves, seems to evoke a little bit of substantiality to it that people are interested in. Even if it’s these mini heads, it’s still a head.

Q. Yes, I think you’re right, it has a sense of finished, of completion, you know? It’s a product. [Laughter.] It’s done. It’s shaped up, right? And plus, there’s that sort of thinking that some people have. Don Tipping, an onion person out of Siskiyou in the West said to me once something about how he spaces onions more in groups as opposed to each plant, each little seedling spaced 6 or 8 inches apart or whatever. [Above, ‘Spretnak’ mini-heads.]

He sort of puts them in clusters, the reason being, who needs a 2-pound onion? When you go to eat an onion, who needs a 2-pound onion and what you were saying, you and your partner, whatever, having supper, how big a head of lettuce do you need? So, it is enough also. There’s a sense of “enoughness,” I think, with these beautiful things. I’ve seen the smaller cabbages you have some of those, in fact I think on your Instagram—you kook—you decorated one as a Christmas tree, didn’t you? [Laughter.]

A. Yes, I think it was one of our customers shared that with us and we re-shared it. That was great.

You’re right. If you think a long time ago, vegetables were a lot bigger. There’s been a trend across all different types of vegetables of downsizing. And that means because families are smaller and again, this is thinking of it in the U.S., families tend to be smaller, maybe people are eating out more, or the idea of having a huge cabbage that takes up literally half a shelf in your fridge, that what are you going to do? Hack away at it every day for 10 days?

Nobody eats like that any more, and so these miniature versions of these familiar things … Again, we’ve got all these mini winter squash, mini Butternuts, and they are concentrated and packed with flavor. There’s zero sacrifice, in fact an emphasis on flavor in all the breeding work that we’re a part of in a mini package.

Q. So, let’s talk about strategy … Before we do the Salanova, Eazyleaf, the ones where it’s a head that when you cut it every leaf is the small size even though it’s the full head, that’s a different thing. So, before we get there, let’s just talk about O.K., I’m in a different part of the country, some listeners are, or it’s a different season, it’s hot, it’s cool, whatever. Generally speaking, what are sort of some of the guidelines for selecting the right variety to grow when, whether in those old-fashioned four groups of lettuces or … How do you say to people, start in the cooler season with this, and finish in the cooler season again with this, and in the middle do this?

A. Yes, I mean, certainly there are some lettuce varieties that are a little bit more tolerant of the heat, and that might mean that they’re bolt-tolerant or they conserve moisture better. Some of the Batavian types of lettuce, which are a little bit glossier, do better in hotter climates. But in general, lettuce really likes, let’s say, 55 to 75 degrees. That is just the sweet spot. And again, Coastal California, that’s what you got. It almost never gets to 80 degrees in many, many places in many places in Coastal California, and it also rarely gets down in to the 40s in a lot of these places, so, it’s been a perfect spot for a lot of lettuce production. [Above, ‘Magenta’ summer crisp lettuce.]

So, they do need moisture, they like a lot of water, and cooler temperatures. But you can start lettuce indoors. Let’s say you’re planting a lettuce in your garden in the fall, but it’s August, it’s too hot. Lettuce seed has a hard time germinating when the soil is too warm and the plants have a hard time; they just need it cooler to start. So, starting them indoors, it’s pretty easy to grow lettuce at least a third of its life in a tray, and then put it out. It’s more convenient for a lot of other reasons, too—weeding or deer eating it or whatever.

Q. And similarly getting a headstart not now, but in the pre-spring period in cooler zones doing the same thing. It doesn’t want to be covered very deep though. Doesn’t it like light to germinate? Is lettuce one of those things?

A. Yes, it does need light to germinate but it doesn’t mean you shouldn’t cover it, just like a little bit.

Q. Don’t bury it deep.

A. No, with most seeds I find that the rule of thumb of … At least if you’re talking about a garden environment where you have some control over to moisture because you’re watering, you shouldn’t really bury the seeds much deeper than two times their longest dimension, their largest dimensions. So in the case of a lettuce you’re talking about maybe an eighth of an inch, a quarter-inch deep.

Q. O.K., so certain things have this heat resistance like the Batavian [also called summer crisp] types you were saying, for instance. What stuff is for extra-cold? And of course, we need to read the variety descriptions and we need as we’re shopping for seeds to choose a palette that takes us through our seasons, right? That’s the strategy?

A. Yes, I mean, again, it depends on how extreme your particular season is. Now, where I am in Vermont, it never gets too hot for lettuce, so from April through October, we’re golden. We’re pushing it a little bit on each end. Then of course, we have winter. Most lettuce varieties even up here will survive in an unheated hoop house during the winter with two layers of row cover. So, we don’t think about lettuce as being super, super hardy but it’s remarkably hardy.

Now, some varieties will grow more quickly in the spring when things finally do start warming up, whereas others will just sort of sit there stuck and then maybe three weeks later they’ll start growing. So you see varietal difference in the growth rate in the spring. But in terms of winter survival, we’ve done a lot of trials and yes, certainly, there are some differences but remarkably, many varieties survive just fine. So if you’re in a place where it’s too cold, consider that row cover can really help with that.

The tricky thing is being in a place where it’s too hot, because again, this is what lettuce doesn’t like. So, the varietal differences: Batavian types are really helpful, starting them indoors, making sure that the seed gets a cool place to germinate, those things all really help. Heat stress is countered a little bit by moisture, so if there’s water, that can help keep the roots cool.

And you can plant it in a shadier part. Let’s say you’re in a really warm place or it’s the time of year, August or July, you can plant it in a little bit of a shadier spot. That just keeps the soil from getting blasted all day and heated up so much. You can also plant it in the shade of other crops in your garden. Taller things.

Q. That’s what I’ve always done, that was a sort of low-tech, old-fashioned thing, you planted on a shady side of the bean teepees or the tomato row or whatever. Yes.

So, these crazy ones now that I see more and more like your Eazyleaf that you feature or Salanova or again there’s probably more types, strains of these. Are these for professional growers or are you finding that home growers are using these, too? Describe them, I guess, first, generally.

A. Yes, so, you described them well earlier. It makes a head. It’s a miniature-sized head but the leaves all emerge from the same point, from the same growth point equally. So, imagine harvesting this and cutting off the stem of it, the rootball of it and you have 50 leaves that are exactly 3 or 4 inches long, and they’re all the same.

And so, there’s a convenience factor there for a home gardener. And for a grower, what you can do instead of pulling the plant up is you just mow them in a similar way that you were mowing baby leaf when you plant it really densely as individual plants. Here you’re mowing the 30 to 50 leaves off the top of this thing, and then you have an established plant root system that can resprout. [Above, ‘Stanford’ Eazyleaf lettuce.]

Q. Oh, so these are cut and come again-ish things, too. I see.

A. Totally can, totally can.

Q. And is the spacing … From the biggest lettuce spacing for like a big head lettuce to the baby leaf, how does our spacing shift and where do these fit in?

A. Yes, they’re somewhere in the middle. So, if you’re doing baby leaf, you’re usually planting 20-plus, 20 to 30 seeds per foot. So, one every half-inch kind of a thing and your rows are, like, 2 inches apart. It’s just like a salad carpet. That’s for baby leaf. Then for these cut and come again Eazyleafs or Salanovas or even the miniature romaines or the mini heads, those are more like on 6-inch centers. Some of them maybe 8 inches. And then you get to your full-size lettuce where they can be 12 inches or even 18 inches apart if you’re growing really big ones.

Q. Right. A lot of readers have been telling me, and I was sort of surprised that home gardeners are doing it more and more, that they’re growing microgreens even in the off seasons, speaking of the smallest thing of all, the youngest thing of all. [Laughter.] So, are people growing those outdoors or just as this sort of in a tray, indoors. What’s that from your experience with customers?

A. Yes. Microgreens are huge. I mean it is a great way, just like sprouts, when you don’t have a lot of room or if you’re in an apartment and you have no access to a garden, or it’s in the middle of winter, you can get some greens for yourself inexpensively and it’ll be delicious and fresh and quick. Like, we’re talking a week or less for both microgreens and sprouts in a lot of cases. Mostly it’s indoors because these are fragile little seedlings.

Q. That’s what I thought.

A. You can sow them in trays and be very space efficient. But generally it’s indoors, and there are so many flavors and shapes and colors.

Q. It’s mind-boggling. You have a great blog post on seven easy steps for growing micro greens that I think Katie Spring maybe wrote, someone who worked for you I think, and she’s a farmer. People can learn how to do it if they want to do it.

In the Stearns household where you have access to everything, I imagine you living in paradise where you can just go outside and get anything and everything. So, what makes it into your salad bowl, or do you have some favorite varieties or ones new or old that you want to tell us about, and also both the greens, lettuces and add-ins as well. [7 steps for growing microgreens from the High Mowing blog.]

A. Yes, well, you’ll like this: I don’t really like lettuce that much.

Q. Now, Tom, you promised not to say that. [Laughter.]

A. No, I like growing it.

Q. I know. I’m teasing you, I’m teasing you.

A. I like growing the seeds especially. But spinach, I’m all about spinach. I mean, you and I have talked about spinach.

Q. And we have a great how to about lime, and how it is one of the unusual vegetables that prefers a little bit of lime, and you gave me lots of good tips and I’ll share those with people again, yes.

A. Yes, so, spinach, kale, some of the more substantial greens that you can really get your teeth around for me are more my favorites. So that’s what makes it into my salad bowl. The arugula also.

Q. I love arugula. And there’s so many different ones, too. It’s not just the plain old one. I mean, there’s different leaf shapes and hotness—I guess that would be word, pepperiness, yes?

A. Yes, Yes. So, but when it comes to lettuce, I do like romaines, I like a crunch, I like something with substantial crunch. And the other kind that I like is in fact sort of the opposite of romaines is the butterheads that are like velvet.

Q. Oh, yes.

A. I mean, these leaves are melt-in-your-mouth buttery and soft and just really quite incredible so those are my two sort of favorite types of lettuce.

Q. And do you guys add into your non-lettuce salads a lot of herbs or are there other things that you always have in the so-called salad garden area that you would recommend us to have a look at?

A. Yes, so I think herbs and salads are great, for sure. I definitely have tomatoes in the salads as often as I can. Things that you wouldn’t grow in the garden too: nuts, cheese, cranberries, dried cranberries, I’m all about those kinds of things in salads. I do really like grated carrots or grated beets in a salad.

Q. Oh, that’s a good idea, that’s a good idea.

A. It’s substantial. Both carrots and beets are super-sweet. So, it adds a lot of that, it adds a lot of moisture so you don’t even necessarily need dressing. I’m not a really big fan of dressing in salads, I use it sometimes. But if you have moisture in there from some of these other things, again shredded beets and shredded carrots are really, really good. So, Yes, those are more my go-to.

Q. So, before we finish, I would ask something I forgot to ask is just about this sort of succession schedule. If I’m going to have lettuce coming and coming and coming through the season, I always used to sort of every 10 days through a short row or a block, I’m a one-person family or I’ve been a two-person family … but how often should we have a succession coming along do you think?

A. That’s not a bad approach. I mean, you might need more for guests coming over. You could get really crazy with planning to make sure you have a lot coming in for the 4th of July party you’re having or whatever. But if you just plant a little bit every week or two and it’s O.K. if it goes by, you know? You can just give it to a neighbor or just till it in and not worry about it so much. Pull it out if it bolts and make room for the next succession. But lettuce can take a month and a half to two and a half months to reach a full size, but baby leaves be 21 days, so if you do get behind it won’t be for long.

Q. All right, so, we’ll do the math. Tom Stearns from High Mowing Organic Seeds. Thank you so much and happy growing and don’t forget to eat some lettuce, Tom. [Laughter.]

A. O.K., I’ll eat some for you, Margaret.

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its ninth year in March 2018. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play Jan. 14, 2019 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

  1. Vickie says:

    Thank you for this lettuce article Margaret. My goal is to provide myself with continuous lettuce so I don’t need to worry when there is a recall such as with the recent Romaine lettuce problem. I live on the Central coast of California, so I should be able to do this. My main problem is germination.

  2. Bee says:

    Great interview on growing lettuce. One thing that I have a problem with is not wanting to harvest the heads because they are so beautiful! I really think lettuce is as pretty as any of my flowers. So, last summer I finally planted extra lettuce so I could keep some as ornamentals in my vegetable garden. They don’t go to waste because I give all the lettuce heads to my ducks at the end of the season. I live in northern Vermont (it is minus twelve here this morning in full sun) so I always start lettuce, spinach etc inside and transplant out.

  3. Another great interview; thank you! I’ve been a bit overwhelmed with all the lettuce options and this along with the links should help! Time to make some note in my High Mowing catalog!

  4. Marjorie says:

    Thank you for the advice on types and how often to plant. My son just finished up a cold frame for me and my goal is to have lettuce year round. Summer will be a challenge but I’ll be working up to it.

  5. I am amazed how few Americans know about Mache (accent on the a), Feld Salad in German. Beautiful, deep green, delicious salad greens for the coldest months of the year. Here in Asheville I can grow it under a light weight tunnel and have nice big heads in February. Local Earthfare and Whole Foods occasionally sell it in a mix but it’s devine all by itself with a simple vinaigrette.

  6. Faith says:

    To follow up on Vickie’s comment about all the recalls – now that the location lettuce was grown and the date it was picked are shown on the package labels, it’s impossible to ignore what the lettuce goes through before it gets to your table! I really balk at buying lettuce that is already 2 or 3 weeks old when it’s not lettuce-growing season here in Wisconsin.

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