I would discard yellow leaves. They are old and have gone 'bad' so to speak.
Only use the new leaves, near the growing ends of the stems. They are the tastiest.
I don't know if overwatering would change the flavor but plants grown dry tend to concentrate their essence, so to speak, and have a stronger flavor.
Is this growing in a window sill? or outside?
I see you are in India. Not a growing environment I am familiar with.
Hey helen, I'm growing this plant on Roof top. I love plants from Mints family (Lamiaceae). When I took a small stem cutting of this plant and put it laterally in a small container with Coco-peat, I couldn't believe it rooted and became this big in a matter of 4-5 months. Apart from this plant, I have Tulsi (which is sacred to Hindus) and Thai-Basil (which I believe is sacred to Christians as I read somewhere " basil plants sprang up from the ground under the Cross where drops of the Savior's blood fell").
I love Basil even more than Tulsi, it's fragrance is so amazing.Basil leaves garland is also offered to Lord Shiva infact a variety of Basil is called Rudra-jada in Telugu language.(Rudra literally means Lord shiva and Jada is ponytail,here it's sacred tuft of Lord shiva)
That's mythology for you, isn't it amazing how the religions lay emphasis on environment and growing Plants ?
Well is it ? I heard this name often as a synonym to Oregano. Thanks for letting me know though and by the way it is called Vaamaku (in Telugu)
Hey there's an interesting point I got from the Wiki link you gave me, see the Cultivation paragraph: It's mentioned that
"The Indian Borage ideally should be grown in a semi-shaded and moist location as the leaves will remain a beautiful jade-green colour. If it is getting too much sun, the leaves turn yellow, start curling and look unsightly; if not enough sun, the leaves turn a dark shade of green and spaced out"
Yest I am now getting the picture, it is not over-watering (as most would think) the reason behind yellowing of leaves, but must be too much sunshine (of course !, after all it's located on roof top)
I can trust that wiki page and take some action because long back when there was three days rain with not much sun I had the leaves becoming dark green.
And so the funny thing I can imagine is that the dark pigment Chlorophyll in leaves will increase (hence turn green) in an attempt to absorb sunlight more efficiently also they space out so that each leaf can do their job like an army unit and the plant would produce it's food.On the other-hand the leaves become Yellow (reducing chlorophyll) and moreover they curl saying the sunshine it's morethan enough for me !!
Well that's leaf dynamics for you
Never know it must be true
And leaf colour is a clue
Even leaves can change hue !!