Best germination temperatures for kale, spinach, lettuce?

2ajsmamaMarch 11, 2014

Just seeded 2 flats, 1 of kale and spinach, the other of lettuce. I know lettuce needs light to germinate (hence the very light covering of mix), but I've never grown spinach and I think I started my kale too early (or left it in flats too late) last year, that germinated well at 67 degrees. But spinach? Do all of these or any of these need cooler temperatures (my basement is about 50 right now)?

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theforgottenone1013(MI zone 5b/6a)

A soil temperature between 45-75*F will work for the things you mention. It will take a little longer (not much longer) for them to germinate at the lower temps. If you do a search for germination charts you'll find a bunch of info. Most of the charts will probably say that spinach can germinate at soil temps of 35-40*F.


    Bookmark   March 11, 2014 at 4:07PM
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Thanks - I did find some pages from Cornell, right now I've got the lettuce on a shelf about the height of windowsill so it gets light, kale and spinach below. I'll probably haul out the 4-shelf mini-greenhouses and the grow lights this weekend.

I sure hope I can plant this cool-weather stuff out a month from now - today was seasonable (a little above) but we still have snow on the ground. I can see a bare patch over the septic tank lid, and the stone wall is visible, though!

Was wondering with the spinach if 67 (assuming soil comes to room temp at some point) was going to actually inhibit germination, and I should put that (and kale, I can separate if needed since I have cells broken into 6- or 12-packs) in the basement where it's cooler?

    Bookmark   March 11, 2014 at 4:26PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

On the Growing from Seed forum there are links to some 15-20 germination databases and most all of them cover this in detail. Why not make use of the information provided there.

Plus all three of those work far better when direct seeded at the proper time rather than grown as transplants.


This post was edited by digdirt on Tue, Mar 11, 14 at 17:18

    Bookmark   March 11, 2014 at 5:15PM
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I have found that spinach germinates best (best compromise between % emergence and speed of germination) when held in the range of 60 to 65 degrees, and kale at between 70 and 75 degrees. Once germinated, both should be held below 70 degrees. I've never grown lettuce.
I do start kale, spinach and chard indoors to get a jump start on the season here, because they reach maturity (and prepare to bolt in the case of spinach) by mid to late May, which is just about a week before I plant out my warm-season crops in the same space. I do manage to salvage the chard, which tolerates being uprooted and moved to a different spot.

    Bookmark   March 11, 2014 at 5:58PM
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I figured with this strange weather, I might as well start transplants. Any broccoli I ever got/bought in May always bolted, never grown spinach, and direct-seeding lettuce last year was a disaster so I figured I'd start it in the house. When I bought lettuce starts from greenhouse 2 years ago it did well. But I always direct-seed cukes and squash since they grow so quickly, peas, beans, and carrots too. I pulled the beet seed out of my mesclun mix to plant later - depending on how muddy, I may direct-seed them with the lettuce transplants, or try to start those (and chard) next month.

I have to look up the address for Growing from Seed - I did look at Cornell and they said spinach only has 30% germination rate at 70 degrees so I was thinking 67 might be a problem too, wanted some opinions.

    Bookmark   March 11, 2014 at 6:23PM
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67 is a bit on the warm side but I think you'll be fine. Uncovered soil will always be cooler than the air temperature anyway.
The best stand I got was seeding outside one particularly warm April, when I estimate the average soil temps. were about 50 degrees. But it took them two weeks.

    Bookmark   March 11, 2014 at 7:06PM
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Last year the lettuce seed got washed out twice by heavy rains. I thought they germinated better indoors if they were covered? I put domes on the flats yesterday, the lettuce got some afternoon sun so a little condensation - think I'll need to take the dome off this afternoon? But the seed is planted so shallow, I don't want it to dry out. I do have a south-facing window by the basement door, I can move them down there if you think that's better but not in the next week - they might freeze. Or since my racks are still set up from trying to ripen tomatoes, I can set up grow lights on those (farther from door), but I don't know if lettuce needs *that* much light before it germinates.

I really should have planted peppers yesterday - hard to believe our last frost is only a little over 2 months away (I hope). Winter weather advisory tonight - tomorrow's high will be 17, low 6 with wind chills below zero. Sat might be warm enough (though rainy) to melt more snow and seed more flats out in the garage - I'll do the peppers then. Maybe tatsoi too, depending on what the 10-day forecast says. Right now looks like snow early next week, waiting to see what the first day of spring will be like!

    Bookmark   March 12, 2014 at 8:12AM
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I germinate in the laundry room which is probably slightly cooler than the rest of the house. Everything germinates. Its more an issue of how soon. There is a temperature range of germination and most stuff will germinate in people temps, what varies is how soon it will germinate. Some are pickier though, I've had more trouble with stuff being too cool than too warm. I had some trays on the concrete floor in the garage and even with the seed mat wouldn't germinate. I put a foam insulation board and towel under to get it going. With your spinach you might want to soak them a day or so before planting. Can't speak to if it's necessary because I've just always done that with any seed that is hard, like spinach and melons and such. There are a lot of people on here that take this a lot more seriously than I do and probably have superior outcomes. My approach is pretty casual but it works. I usually have more seedlings than I have room for. BTW, I think Johnnys seed used to have a chart in their catalog that showed percentage of germination for different plants at different temps. I don't know if they still have that. Maybe it's on their website.

    Bookmark   March 12, 2014 at 5:01PM
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found this hope it helps

Here is a link that might be useful: germination temps

    Bookmark   March 12, 2014 at 5:05PM
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Thanks, that's a handy chart. Just read the "spinach quick to bolt" thread, looks like I should move it to the basement once it's germinated.

    Bookmark   March 12, 2014 at 9:16PM
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I found another seed germination guide with more info. Great -- except those Canadians -- they didn't take into consideration their backward American cousins and put the numbers into F as well as C.

Vegetable Crop Overview �" Germination / Days to Maturity, etc.âÂÂ
Vegetable Crop Overview �" Germination / Days to Maturity, etc. Crop. Minimum. Germination. Temperature. (ðC). Optimum. Germination. Temperature.

    Bookmark   March 15, 2014 at 2:48PM
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Kale is starting, spinach just a few since seeding on Tuesday (too warm at 67 degrees? About to move everything to basement). Lettuce germinated in 3 days and it's crowded - I tried for 5 seeds per cell since seed was packed for 2012, I bought it end of year to use 2013. But some cells have a dozen seedlings in them!

When to thin (1-2" like outside)? Can these be separated and when? Starting peppers today.

    Bookmark   March 15, 2014 at 3:01PM
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Call me crazy but I thin that little tiny stuff with a cuticle scissor. Just snip the ones you don't want. I figure the sooner I get the extras out the better the others will do.

    Bookmark   March 16, 2014 at 4:46PM
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