DigitalVinyl said:

Hi I'm a beginning gardener. I am growing some peppers indoors to
transplant when it is warmer. As a practice I transplanted some of the
extra plants in to a window box (still inside) that was empty.

Some of the leaves on 5 out of seven plants are developing pale areas,
beggining on one side of veins and spreading outward to fill the space
between vanes. Some transplanted Parsleys also have it faintly on
their leaves. I scanned a picture, but frankly they look healthier
and greener in the scan than in real life. But you can see the whitish
line developing alongside one side of the large leaf's veins.

http://members.aol.com/royalef/leaves.jpg

It does look like sunburn. Were these plants started under lights and then
moved to a sunny window?

I tend to move plants outside to areas where I know they will get some sun
but be covered by dappled shade, sooner (when first taking them out) or
later (as they get better adapted).

--
Pat in Plymouth MI

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)