Tomato Leaf Discoloration

A few hours in a sunny spot? That might be enough to sunburn some tender leaves. The seedlings need to be gradually acclimatized to full sunlight. I usually place them where they will get indirect light or dappled shade the first time they go out, then place them farther and farther ahead of the shadows.

Indoor plants will also need shelter from the wind when they first go out. I run a fan on my seedlings while they are indoors. The air circulation is good for them and the breeze helps toughen them up a bit.

Were they on the outside of the flat?

I think it's just plain sunburn. If it was a windy day, the leaves could have been battered some, too. Pat's advice is spot on, and pretty much what I do, too. Filtered sunlight for a few days, then slowly moving the plants out to where they get a little bit more sunlight each day.

If you don't have a handy tree, try making a low tent out of a light colored sheet. Just be sure that the plants are positioned so that as the sun moves across the sky, they don't get any direct sunlight. After a few days of this bright indirect sunlight, you can move the plants to where they get a little bit of morning sun, but are protected by nine or ten o'clock, depending on your location. Then each day let them get a little bit more sun.

Good luck!

Penelope

The blotches that you found on your tomato were porabably sun burn, you said that they were under shop lights, that plants that are grown inside are not yet used to real direct sun light, once you put them under the sun it will effect them with a sunburn, this should go away in couple of days, as the plants get used to the real sun.

Good luck

To diagnose, check out:

I/ve noticed the same thing with my seedlings grown under lights - a lighter green patch in the leaf/s center. I/ve sen it happen with Bell peppers, too.

Not to worry. When all is said and done, it won/t be a problem.

Harden off your plants for about a week when min temperatures average ~55°F, set them in the garden, and you/ll be fine.

Thank you everyone for your advice. I removed the affected leaves and the plants seem to be doing fine.

Does anyone have a good fertilizer suggestion? There seems to be too many options.

I water seedlings with fish oil emulsion, then side dress with 5-10-10 fertilizer about a week after setting them in the garden. Once a month I foliar feed with a 2-3-1 seaweed solution. Avoid high nitrogen fertilizers or you/ll end up with all vine and no fruits.

Well, for seedlings I like the fertilizer sold by Gardener's Supply Company: