Paste Tomato Seedling Problems

14 years ago

Hi all,

I started some Roma and Italian paste tomato seeds about 18 days ago. They germinated quickly and are now about 4 to 5 inches tall. I'm growing them under grow lights in plastic cups with drainage holes. They haven't been exposed to any fertilizer or herbicide, and the soil used is regular seed starting soil from Home Depot. I try to keep the temperature around 70 to 75F.

Up until a week ago, they were doing great - great color and strong stems. Then, they started drooping a little and some of the bottom leaves are starting to curl downward. They've also developed some water blisters on the undersides of a few leaves. I did some research and found that over-watering might be a cause. (I've seen since cut back to only watering them when the soil's mostly dry). But as the days ago by, the leaves are begin to curl downward more and more. Some have a purple tinge which I understand might be a phosphorus deficiency (either lack of nutrient in soil or too cold). The upper, newer growth seem to be fine thus far and the plants continue to put out more and more roots. This is the second year this has happened to me and I'm confused. Anyone have any ideas?

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Comments (5)

capoman
14 years ago
The blisters are likely edema. Edema is usually caused by a combination of wet warm soil, and high humidity in the air. The blisters are a result of roots supplying more water to the leaves then they can transpire, bursting cells.

If you are on a heat mat, remove it or reduce the temperature. Do not overwater, and if you can reduce the humidity, please do. Make sure a fan is blowing lightly on the seedlings helping transpiration. Plants usually fully recover from edema once the cause(s) are corrected.

As far as the purple under the leaves, that is a common deficiency in young plants and will resolve itself. Don't overdose on phosphorous. It's really just that young roots aren't supplying phosphorous fast enough for the fast growing leaves, and will recover as the plant matures.
Bsze
Original Author
14 years ago
Thanks for the useful info! There isn't much humidity in the room I keep them in, but it does get pretty toasty in there. (It's a 6 by 7 laundry room and we keep the door to the rest of the house closed.) I dropped the temperature so I hope the edema goes away soon. Could overwatering be a cause of the leaf curl too? As far as I know, the seedlings haven't been exposed to any bugs. The rest of my pepper seedlings are doing fine.
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ikea_gw
14 years ago
Do you have anything like a gas dryer or furnace in there by any chance?
capoman
14 years ago
Yes, overwatering can cause edema and leaf curl. It's not unusual to see edema and leaf curling on the same plant. Are your plants sitting on a warm dryer or something? Great for seed germination, not so great for tomatoes that have leaves. Too much of a temperature difference between roots and leaves plus too much water are prime conditions for edema/curling.
Bsze
Original Author
14 years ago
We have an electric dryer and small electric space heater in the area. The plants are on a shelf 1 1/2 foot above the laundry appliances. Also, since it's just my husband and I, we don't run the dryer very often. I just noticed too that the only the Italian tomatoes have edema while the leaf curl is only on the Romas. I thought tomatoes are supposed to be easy! LOL. My other seedlings (peppers and watermelons) are thriving so I hope the decreased temperatures won't negatively affect them. ::