Are you growing them in garden soil? Perhaps it's the medium. The temps there don't sound too bad to me.

Linda

The soil I'm using is sifted compost, which is the same soil I used last year.

A simple peat based seed-starting mix is recommended. Any chance you could grab a small bag of it and start some more. Compost?? I don't know. A little more info is also helpful. Where are they, temps, watering, light??

Little tiny plants in great big pots? Compost is great for the garden but not for starting seeds.

They can easily drown and develop root rot with all the moisture those pots hold. And if you over-water them the problem is only made worse.

There is a good How to grow tomatoes from seed FAQ here as well as even more FAQs covering all the basics on how to do it successfully over on the Growing from Seed forum.

Dave

Well like I said the day time temps have been in the high 60's to low 70's and night time has been in the 50's. I started the seeds outside so they have been getting sun from early morning to late evening. I have been watering only when the soil is dry a few inches down.

I wouldn't think the soil is the problem because I did this with the seeds I collected from a grocery store tomato last year and they did great. The plants got to 10' tall.

It is all so different from the common and recommended methods that there really isn't anyway to know what the issue is other than to say much of what you are doing has been proven to not work well by many of us.

Perhaps last year was just luck, perhaps the outside weather was different, perhaps the compost you used was more nutrient rich or had a more active soil food web, perhaps you watered differently, etc.

But statistically the most common causes of stunted growth is the media they are growing in and the balance of moisture that is maintained in ratio to root development.

Compost provides minimal nutrients in containers since there is no active soil food web to act on it so a good feeding of a diluted, well balanced fertilizer might kick-start them.

Dave

I am in the East Bay, my plants are 12+ inches in quart pots, and I put them out at night starting about two weeks ago. But every night I brought the close to the house and covered them. I still am, because it is still dropping below 55, and sometimes below 50 here.

I have never tried to start seeds in my compost, although voulnteers certainly start there on occassion.

I am seeing that purplish color on the underside of tge leaves that tomato seedlings get when they are cold. I seem to remember it indicates a nutitional deficiency; maybe Mg, but I mostly remember it means they are cold.

I believe "nanelle" nailed it.

Growing , medium is secondary. COLD is the primary problem.
CASE IN POIT:
I have two seedlings that I took outside after shutting down my indoor grow operation. They are there but not growing as nearly as fast as they would indoor under lights.

If you want your seedling grow, they need no less than 65F around the clock, UNTIL they develop their root system and enough foliage to get going.

ONE MORE THING:
I would fertilize them WEAKLY , WEEKLY(1/3 normal rec.)

Nick since you don't think the media they are growing is not the problem can I suggest an easy test to find out?

Buy a small bag of a good potting mix - not soil, mix - and transplant one of the plants into it, preferably in a somewhat smaller container if you have one, water carefully, and watch what happens. You can learn alot from comparative studies like this and it is good info to have for future reference.

While the plants may be slightly purple and while that can be a symptom that they are low in phos, it is also very common in healthy young transplants. Plus phos isn't a top growth stimulant anyway so even if they are low in P it wouldn't explain the stunted growth directly.

And the temps you have related are common temps and no problem even for greenhouse growers this time of year.

Most gardeners know from experience that the growing medium is the primary source of growth issues so try the media change test and see what happens. :)

Dave

Frustrating watching lots of folks trying to reinvent the wheel, then asking what's wrong. Like was suggested there is a FAQ on how to start seedlings. Very simple....even I can do it. Mini-rant I'm sorry :-)

@ Edweather,

In the sam FAQ it says( quote below)

"Slow Growth
When seedlings refuse to grow it is usually because the temperature is too low or the nutrient level is insufficient. "

That is what "nanelle" and I have mentioned.

One has to realize that medium is just that "MEDIUM" a mediator. So as long is it has proper moisture retention/drainage and supplied with needed nutrients , it make littl difference as what it is made of. SURELY, some media are better b'c they offer a better and balanced moisture retention. Believe or not , I have germinated all kinds of tomatoes, peppers, eggplants in garden soil in the past. Not the best, I admit but it can be done.

But sowing seed in 3" (or deeper?) of compost and watering only when it's dry "a few inches down" doesn't help. The roots aren't that long yet.