Hi all,
Long time grower of tomatoes but the last few years I've had problems with tomato starts new growth twisting and curling and stunted to no growth. Over the last three years I've been trying to eliminate possible causes but the problem showed up even sooner this year. My latest wild guess is the added use of led instead of fluorescent and having them to close like 2 inches. The Brandywine and Paul robeson seem fine but Mortgage lifter and Strawberry are bad.

I would suspect whatever it is that you are growing them in. If the potting mix contains manure, it could contain herbicides.

I would suspect herbacide contact someplace in your growing process. I would thoroughly wash and disinfect all your pots, seed trays and utensils for next year. And 2” is way to close for led lights. Back off the light to 10”. So what is a common link for the last 3 yrs. Potting soil ? Seed Starter mix ? Do you re-use pots from year to year ?

Having the plants too close to LED lights is very hard on them. I don't have strong LED's but I still keep the plants 24" away. My plants will sulk if the lights are on too long for them. See if they perk up at all while they are in the dark. If they do then place the lights higher and when they start to droop give them a break.

If the lights don't seem to be the problem then I would suspect that you may have a herbicide in the soil.

Thanks for feedback. I've used various miracle grow potting soils over the years. I'm not suspicious of it. Been sterilizing pots. Used different seed suppliers. Starting to think certain varieties are more sensitive to the LEDs.

Are they LED grow lights or standard household LED's? I haven't noticed any issues with my LED grow lights. I don't recall using them at two inches but three inches for sure often from day one.

Hi, do you have a water softener in your home and is that the water you are giving the plants?

Judging by the leaf curl I would suggest herbicide damage or perhaps a virus, but since you've used a variety of potting mixes and seed suppliers over a number of years it seems like the light may be the culprit. My LED lights are about a foot away from the canopy and only on for 12 hours a day. There are free phone apps which you can use to measure the light intensity and see if your plants are getting too high a DLI (daily light integral).

What sort of LED light are you using?

Some tomato varieties get intumescence when grown under LED lights, which do not emit UVB light. However like many others have written, that curling of growth looks like herbicide damage and not intumescence.

Have you fertilized your plants with an organic fertilizer? There has been a lot of problems in Europe with fertilizers made from sugar beet vinasse or molasses, so the herbicide residue risk is not only with manure based fertilizers.
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Dalefitz wrote: ↑Thu Apr 17, 2025 9:06 am Hi all,
Long time grower of tomatoes but the last few years I've had problems with tomato starts new growth twisting and curling and stunted to no growth. Over the last three years I've been trying to eliminate possible causes but the problem showed up even sooner this year.

Have you used a different starting mix during this past three year period that you hadn't used before? Like some of the others I'm suspecting herbicide damage especially if you're using something new to you that contains "compost" as an ingredient. Any compost made with manure that has come from animals that have grazed in pastures treated with Grazon or similar herbicide will taint the compost. I lost a bunch of tomatoes three years ago due to that. Confirmed by local Extension agent.