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Questions about lettuce under lights

Posted by DanaNY z6 Brooklyn, NY (My Page) on
Mon, Feb 7, 05 at 19:51

What kind of lettuce does well indoors under lights in 70F degrees? Should I be looking at summer crisp lettuce? How many should be planted to get a steady supply for 1 or 2 people? I'm all set with the lights and will also be growing tomatoes (Red Robin), but I really have no idea about the lettuce. I hope someone who's done it can help me out or provide some info, thanks.

Also, are there any good books on growing veggies/fruit under lights?

Follow-Up Postings:

RE: Questions about lettuce under lights

I'd like to hear the answer to that myself.

I'm getting together a light rack and plan to start with lettuce. I like Marville de Four Seasons in the Spring, but it's a heading type.

For continuous harvest, Royal Oakleaf might be best. It's a leaf type, but shaped like Oak Leaves. Very thick, tasty oak leaves.

As I recall, it grows back, which head types don't.

Then there's mini-head types like Tom Thumb.

And if you really want to impress everybody, grow Roquette.

Roquette, AKA Rocket, is a spicy green that grows like a ... Rocket.

I don't care for it, as I don't do much spicy.

You know how a Jalapeno has that warning that hits your tongue, telling you you've been stupid?

It's like smoke before fire, when the real heat kicks in.

Well, Rocket is all smoke. The fire never hits.

French Sorrel is a nice green too. It's a bit sour-tangy. Good in soups, and mixed into salads.

And although I haven't done it, you can start brocolli sprouts for salads.

RE: Questions about lettuce under lights

  • Posted by Bunn 5 B St. Louis Area (My Page) on
    Fri, Feb 11, 05 at 1:12

I tried starting lettuce seedlings under lights for the first time last year and had good luck with Buttercrunch, which grows into a thick, curly, leafy ball but not quite a head. Very nice--delicious. It grows well at 70 degrees under lights, but I'd be afraid to push it. I have it growing under lights, right now.

Like spinach, it is sensitive to light, which, when given too much, will cause lettuce to bolt prematurely. However, this particular cultivar seems slow to bolt, and last year I had it until very hot weather, and it was still sweet, mild, and tasty.

As far as the amount of light, I'd keep it down to 12 hours a day and then place it in a dark unheated room. We are lucky enough to have one; I hope you are. 50 degrees is about right. Keeping at a low temperature at night is important.

As soon as your seedlings are leafing out and look like they are fairly tough, put them in a cold frame, if possible. Lettuce takes a little bit of frost.

One more suggestion: Look up the book, Vegetable Secrets by Dorothy Hinshaw Patent & Diane E. Bilderback for more information. I got a copy from the library and will probably buy it.

If you find a good book about growing vegetable seedlings under lights, please post it. In fact, looking for a book about the growing needs of specific vegetable seedlings, like lettuce and spinach, led me to your query. I hope this helps. Good growing to you.


RE: Questions about lettuce under lights

"Like spinach, it is sensitive to light, which, when given too much, will cause lettuce to bolt prematurely."

Last year, I talked to a fellow who swore that it's not heat that makes lettuce bolt in the summer.

He says it's day length. And day length only.

So, if you made a trellis over your lettuce row in the garden and threw floating row cover fabric over it, you could shade the lettuce during the brightest part of the day.

As this applies to growing under lights, with a simple timer we can strictly control the day length the lettuce gets.

Maybe it's possible to have lettuce year 'round this way.

RE: Questions about lettuce under lights

  • Posted by DanaNY z6 Brooklyn, NY (My Page) on
    Fri, Feb 11, 05 at 14:55

Thanks for all the suggestions. Unfortunately, in my case I don't have an extra room or an unheated one since I'm in an apt. I'm also growing other things under my lights which are on a 16 hour schedule and can't change it. I guess it could be covered with something to block the light for just a few hours.

The summer crisps are heat tolerant and slow to bolt. If they can take the hot summer heat, they should do fine in room temps. There are a few other varieties that are also heat tolerant. I'm still looking into this.

RE: Questions about lettuce under lights

  • Posted by Bunn 5B St. Louis Area (My Page) on
    Fri, Feb 11, 05 at 18:27

Hi, DanaNY,

That's what I'd do. Cover the plants to block the light (for your lettuce). I'd make sure the light is completely blocked and that they have some ventilation. According to the ladies who wrote Vegetable Secrets, even streetlights during the night have a detrimental effect.

However, when I lived in the city and had a garden in my backyard, which was exposed to a little streetlight, my spinach grew wonderfully. (I didn't grow lettuce there.) But it's better to play safe, I think.

I forgot to mention that last year I also grew a cultivar named Crispino, a head lettuce. I bought the seeds from Johnny's Selected Seeds. It too, did very well and formed fine crisp heads of lettuce.

If only I could, I'd try them all. ----- Bunn

RE: Questions about lettuce under lights

  • Posted by DanaNY z6 Brooklyn, NY (My Page) on
    Sun, Feb 13, 05 at 18:50

Hi Bunn, does the heading type just grow one head and that's it or does it grow more? Btw, I think the summer crisp is like your buttercrisp that you grew, only more heat tolerant. I'm still undecided if I'll try a heading type or leaf lettuce. Maybe I'll try both. I think I prefer a heading type though.

Have you tried other veggies or fruit under your lights? I want to try a few others. Luckily the rest are warm growers. Still need to find a good book on it before I attempt it. Does the Vegetable Secrets book have photos in it? I don't see it listed on Amazon. Out of print maybe?

RE: Questions about lettuce under lights


I didn't keep track, but it seems like the Buttercrunch (thick, curly leafed, almost-a-head) grows more quickly than the heading type lettuce, Crispino, which grows slowly into a single head, and that's it.

I understand you can use Buttercrunch as a cut-and-come-again vegetable. I haven't tried to cut-and-come-again with lettuce, I eat it all at once. But I do do it with kale and collards, taking some from each of several plants.

I don't know how I did this, but in rereading my message to you before, I wrote about covering the lettuce to block the light. I was thinking of spinach when I wrote that and crossed my wires. I think that it's the amount of light (sunshine hours) in a day that affects the bolting of spinach, and the amount of light altogether (through the season) that affects the flowering or bolting of lettuce.

I am sorry for any confusion. Still, I'm keeping my spinach and lettuce on a twelve hour light schedule, then putting them outside on the porch, or in an unheated room, or in the cold frame at night--depending on which one seems to have the right temperature. They are doing fine. Squat, strong, and sturdy looking.

I start everything from seed. I have onions; leeks (in flats outside protected); and cabbage; joi choi; turnips--you can transplant them with no problem; spinach; kale; lettuce--Buttercrunch and Crispino, again. I've grown these successfully under lights. Keeping them cool at night is one of the hardest things. It seems either too warm or much too cold. I've read that if one should err, to err on the cold side. I start other plants like tomatoes, peppers, squash, and aubergines under lights. But they are a bit easier than the cold weather crops.

Oh, and we keep parsley, rosemary, and basil under lights during the winter under the lights. They are easy to grow and little trouble for the joy they give to my wife and me in the kitchen.

As for the book, it isn't out of print. I've seen it listed recently in the back of one of the seed catalogs. It has pictures--good ones; I'm not sure what kind you're looking for, though. I'll try to find it. Vegetable Secrets has only a chapter about plants and light, but they go into detail about lettuce and spinach, there, and its knowledge I've not seen in other books. Good growing to you. ---- Bunn

RE: Questions about lettuce under lights

  • Posted by DanaNY z6 Brooklyn, NY (My Page) on
    Mon, Feb 14, 05 at 16:08

Hi Bunn,

Oh, no problem and thanks for all the tips. I confused Buttercrunch with Buttercrisp, but you probably knew what I meant. lol

I grow everything from seed also and my kitchen has been turned into a small grow room. The coolest it gets in there at night is 64, but that's rare, 68-70 is the norm. Tomatoes should do well, I can probably get away with the lettuce, and warm growers like baby bell peppers and eggplant. Of course I won't try to do this all at once. I wouldn't have enough room for all that anyway.

I was so disappointed when I found out strawberries need cold temps. There are heat tolerant varieties, but they may still need cooler temps to bloom and grow fruit. Not really sure about that, but that's why a book will really help. I'll try to stop by the library soon and take a look before I buy one. I'll see if I can find the book you mentioned. But I think the library near me is closed until spring (it figures). I just found out we're going away next month anyway, so I'll have to hold off on planting anything until I get back. Now I have to figure out a way to keep my other plants alive while I'm gone. :o

Have a nice Valentine's Day!

RE: Questions about lettuce under lights

  • Posted by Bunn Z - 5 B (My Page) on
    Fri, Feb 18, 05 at 19:47

To Dana of Brooklyn,

My wife sent for Garden Secrets for my "Spring" present. (Yaaay) I asked where she found it, and she told me she found a slightly damaged used copy from Amazon. --- Bunn

RE: Questions about lettuce under lights

  • Posted by DanaNY z6 Brooklyn, NY (My Page) on
    Sat, Feb 19, 05 at 16:09

Hi Bunn, I finally found it under the name The Book of Garden Secrets. It appears to be out of print, but your wife is right, they are selling used copies thru Amazon Marketplace. Thanks for alerting me to it and enjoy your new book!

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