Tomato Seeds Not Germinating

jcrowder(7)March 20, 2011

I planted tomato seeds in flats about 3 weeks ago and I haven't seen any sprouts in some of them yet. I have them in my greenhouse outside (a cold greenhouse). Today, my impatience got the best of me so I started moving a little soil away to see if there were any signs of life. I didn't see anything; not a sprout, not a seed, nothing! Where did they go????

Here's what I've planted and what has germinated:

Beefsteak: They are about 1" tall

Grape: They are about 1" tall

Roma's: Nothing

Rutgers: One flat came up beautifully, the other, nothing

Large Cherry: Nothing

Any advice or ideas on what I've done wrong?

Maybe it's too cold in my greenhouse at night. This is my first round at using a greenhouse so this may be my year to learn the hard way!!!!

Thanks ya'll!

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natal(Louisiana 8b)

Did you give them any bottom heat? Mine get started on top of the fridge or on a seed heat mat.

    Bookmark   March 20, 2011 at 8:10PM
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helenh(z6 SW MO)

I wouldn't think you could see any impatiens seed mixed in the soil. They like heat and take a while to come up - longer than tomatoes. Can you bring them inside just until they sprout? Do you have a minimum/maximum thermometer in the greenhouse to know how cold it is getting at night?

    Bookmark   March 21, 2011 at 12:24AM
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helenh, his impatience; not the flower.

I'm thinking seed planting depth, soil moisture, and MAINLY inconsistent warmth are contributing here. Most greenhouses have an over head furnace, and also venting to maintain a +/- 15 degree swing in temp. Re-plant Rutgers seeds. Your Roma and Large Cherry seeds could all be defective, though doubtful. Either re-order from another source or re-plant I guess. -Randy

    Bookmark   March 21, 2011 at 1:21AM
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helenh(z6 SW MO)

Duh How stupid of me. I guess I am thinking of my impatiens which are not up yet. I still think you need a thermometer that tells you min/max if you don't have one.

    Bookmark   March 21, 2011 at 1:36AM
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It probably is the cool nights...I will replant and keep a better temperature for them!

Thanks for all the advice!

    Bookmark   March 21, 2011 at 12:02PM
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Bets(z6A S ID)


I think you may have two issues here (possibly 3 if you got a bad batch of seeds, pretty rare for that to happen though.) I find that when I have low germination, it is usually due to something I have done (or had happen) like planting the seeds too deep.

I prepare my tomato, pepper and egg plant seed starting containers and level the top of the moistened medium about a half inch below the lip of the cell, flat, or what ever I am using. Then I put the seeds on the growing medium (never use dirt, a soiless seed starting mix is best) then I sprinkle a very thin layer of the same mix over the seeds. Most seed packet say to cover them 1/8 to 1/4 of an inch deep. I feel that 1/4" is too deep. One seed company's directions say they should be surface sown or covered very lightly. I like the covered lightly version.

You are probably right that it is the night time temperatures. I have a new greenhouse and will be starting my seeds about April 1. I plan to start them indoors on my heat mat, move them off the heat when they sprout, then move them to the greenhouse when they are a couple of inches tall. I do have one of the min/max thermometers and plan to monitor the highs and lows in there for the next week or two so that I'll have a good idea on what to expect, such as if I need to add a bit of supplemental heat if we are expecting real cold spell.

I hope that helps.


    Bookmark   March 21, 2011 at 3:10PM
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Here is a link I use as a reference for starting seeds. It charts the relationship between soil temperature, days to seedling emergence, and the germination rate:

I use heat mats for trays of seedlings. I've found that heat mats work well for getting my tomato and pepper seeds to the optimum temperature. My best guess is that oscillating temperatures in your coldhouse are the culprit, but without more info it is impossible to say for sure!

Good luck!

    Bookmark   March 22, 2011 at 9:19AM
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