Granite - I'm a Botanist. I'm pretty sure that is NOT cilantro that is hot. You must have mistaken some other plant for it. And be very careful because there are extremely toxic plants in the family (Parsley Family/ Apiaciae). You are probably eating a mustard family plant like a cress or mustard (from mustard seed that you also composted?). I also keep sprouting seeds with my spices - so it could be another plant from that family like radish, if you also keep some of those seeds around. See if when it flowers it forms an umbel (like an umbrella) with the flowers in the ends of the 'spokes'. If so it's in the parsley family - but then photograph it and post it. If it does not flower (from a Spring sprout) - it's not cilantro either, as cilantro bolts very easily. Also - The cilantro I buy is often without nearly any flavor. When I grow it, it has lots. Some people think it's soapy - but in reality it's not soap, but the fragrances that are often put in dish soap, especially a popular one that is green. I can't stand scented dish soap so use unscented (though it slightly smells of the citrus oils they use as grease cutters). I don't think cilantro is soap-like myself, though it is very understandable. Cilantro also tastes very differently once it starts to produce flowers. It's often referred to as smelling of fleas - though human fleas are not at all common anymore so I have no idea (human fleas are a different species than the common cat or dog flea)! I still like it then, but it's not like the plant before that stage - and that may be more soap-like to some. Then the green seeds have another aroma, which then changes onces they are dry. So it's quite a unique plant. I did not like it at all when I grew it in our family garden when I was about 16 (years and years ago). Now I love it.

Are you thinking that this is a nutrition thing and nothing like some kind a disease? ==>>> lack of light. IS A NUTRITION thing.. in that the plant can not photosynthesize enough for the plant to thrive ... BUT YOU CAN NOT OVERCOME LACK OF LIGHT THRU FERT ... ever ... did you look into your plant.. and find out where the brand new growth comes from.. perhaps the center.. and whether this is fresh from the center.. or out at the edge.. the ones at the edge are older??? such varies according to the plant.. YOU HAVE TO LOOK .. and though you claim your house is warm ... is it consistent all night long.. or do you kick back the heat??? .. why dont you get up around 3am.. and put your hand near the window and plant.. find out just how chilly it is ... IMHO ... its light and heat.. said it twice now.... and your reply is.. should i fert it ... never fert a stressed plant... find out whats stressing it ... good luck with the second light.. how close will that one be???? disease is a long shot.. in a single plant.. in a given house ... i just dont buy it.. on the facts provided ... BTW.. did you use new media.. or old used potting soil .. or even worse.. dirt??? ... either of those could bring in disease ... if not properly sterilized ... prior to use .... perhaps a pic of the whole might help???? its hard to grow food plants indoors ... and keep in mind.. by the time you start running two lights ... plus the cost of both lights .. you are going to be spending a lot more money.. than it would cost.. to just go buy the cilantro.. at the store .... its fun to try these things.. but keep the cost/benefit ratio.. clearly in mind .... that is one of the reasons.. i gave up doing this .. long ago .... as to houseplants.. i have very few.. and only those.. that after years of abuse.. thrive in the native conditions of my house ... no matter how dark winter is.. and no matter how cold i set the furnace at night.. and ones that can cope with whatever light comes thru the winter window .... and you can read that to understand.. i killed a lot of them.. lol ... think about when a plant.. comes to maturity outside.. your vegetables ... and herbs... mature.. in the warm soils of mid to late summer, when the sun is at its apex ... and let me suggest.. that your house in winter.. is not equivalent [i even forgot about humidity as a variable.. if you have a forced furnace, that can be all screwed up as the furnace burns all the moisture out of the air] ... and on that logic.. that is why your plant is not THRIVING ... but simply coping ... and also.. under this logic.. i dont need to jump to disease .... as there is just so much variance to it growing in mother nature ... you are on a grand learning curve here.. dont give up hope.. or trying.. even if you get so frustrated.. you just whip the plant out the back door in the dead of winter.. lol.. been there done that.. started over... lol ... ken ps: even if it is disease... how do you treat a food plant???.. in the house.. in winter??? that is when it goes flying out the back door ... lol ... and treatment.. would be another 10 bucks min. invested .... at some point.. its just not worth it ...

We grow cilantro year round, but it does much better in the Fall/winter/spring than in summer. I start seeds in small pods placed in full sun with ample water. Then I transfer the seedlings to raised outdoor beds in either full shade (summer) or partial shade (fall/winter/spring). This is the only thing that has worked for me and using this method, I did mange to grow cilantro all summer. If I try to direct seed in a shady location, the seed never germinates or is very weak. If I try to direct seed in a sunny location, it bolts before I get a significant crop.

@HighColdDesert you read of my growing cilantro elsewhere. I had four envelops of cilantro seeds from four different sources. I treated them all the same and tried to grow some of each at the same time. All the seeds of Calypso germinated and not a single one of the seeds from the other types did. I have read about some people having trouble with parsley. Now I hear of chervil not germinating for you. I am getting think this group of herbs can be temperamental until you get the hang of them. May be the source of the seeds matters? If I may ask, where did you get your chervil seeds? I got mine from Richter's this winter. But I have a bad feeling. Some eggplant seeds I got from Richter's did not germinate. I dont know much about Richters seeds. I think you can transplant cilantro seedlings without them bolting if you are super careful during the transfer and the plants are not in full sun. A slow bolt variety maybe important too.