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I wanted to grow spinach, lettuce, cilantro and rosemary in pots through this fall and winter, but so far, it has not gone well. I planted the seeds and used rich potting soil. Some of the seeds did not sprout at all. The ones that did sprout came up quickly but are now languishing. They have wilted or disappeared altogether. I don't think I over watered them. The soil was warm and moist, and I set them where the sun comes in through a window. What could be wrong? What do I need to do differently? Does anyone have any ideas that would help?

Right offhand, without asking a lot of questions, my guess would be that the problem was the potting mix. Most herbs do best in a mix with a higher pH, around 6 to 7.5, and most potting mixes are more acidic than that.

Container-grown plants require a potting medium that drains rapidly, so if you mixed a lot of compost into your soil, or perhaps began with garden soil, then the drainage was likely insufficient. With poorly draining soil in a container, the top will dry to the point of looking like a desert, but the soil in the bottom 1/3 of the container will remain waterlogged.

IMO, poor drainage and wrong pH are the cause of the most common problems people have when they begin to explore container gardening. I know because I made the very same mistakes myself.

Sunlight coming through a window is about the same intensity as medium-deep shade outdoors. In addition, plants that are placed close enough to the glass to benefit from the sunlight will also be exposed to heat, because some of the light energy is converted to heat energy as it passes through the glass. Supplemental light is almost always necessary, in order to provide not only sufficient intensity of the light, but also to provide the appropriate 'day length', I.e. the number of hours of bright light the plant receives each day. Six hours of very bright light is considered "full sun", which is what most plants need to thrive. Greens like spinach and lettuce can get by with slightly fewer hours, but they don't tolerate heat well.

I agree that "rich potting soil" doesn't sound very promising for seed starting. Some seeds will actually be inhibited from sprouting in rich soil.

That said, under good conditions I would expect lettuce and cilantro to sprout in a week but spinach may not sprout for 2 weeks and Rosemary, I understand, takes even longer than that.

After they do sprout, even sunny windowsill right by the glass, especially this time of the year with diminishing daylight hours and weaker intensity, is not likely to provide enough light for good growth. I might have been able to tell you if lettuce would grow in a SE exposure windowsill, except I forgot that my cats love lettuce... I had a little lettuce seedling with two sets of leaves growing but they were basically stubs this morning. . I WAS planning to move it under the grow lights where I'm attempting to root some pepper cuttings because I thought it was getting a bit spindly from lack of light though.

Agree that it is really difficult to grow very much edibles indoors without supplemental lighting. But I'm looking at that "wilted or disappeared all together." To me that sounds different than a lighting issue. Plants with not enough light tend to get leggy, tall and spindly as they shoot up searching for light.

Plants will wilt if they are not getting enough water, but you would probably know that and they would start to look dried out. But they also wilt with too much moisture. I know you said "not over watered," but you also said "rich potting soil," which almost certainly has a high peat content. That means it can hold moisture for a long time. Depending on drainage issues, your plants could be staying too damp especially in the root zone. The soil could be dry on top and still be very wet where the roots are, if it is not draining well. Pull one of the not doing well ones out of the pot and see what it looks like at the bottom.

Also re the disappearing all together, have you found any of them lying flat on the soil? Little seedlings are very vulnerable to damping off, a fungal condition that is promoted by too much moisture and too little air circulation.