Question
I have two batches of basil plants I'm growing from seeds and am having problems with both.

I planted the first batch of seeds in two pots sometime before christmas and for a while they were doing well; they sprouted quickly and then carried on growing, looking perfectly healthy. Then all but four of them died, and I have no idea why. I repotted the survivors, of which only two are now left - having grown not a jot since the repotting, weeks ago. They're perfectly green and healthy-looking, just not getting any bigger.

I planted the second batch within the last month, this time using purple basil. Again, they sprouted nice and quickly... only to start dying again! They've just bent over and their leaves seem to have shrivelled - their first set of leaves, barely even developed yet. I'm making a concious effort not to overwater them, only doing so every few days when the soil seems dry, and have fed them twice. There's also some kind of white mould on the soil. I think this batch is essentially doomed but I'd like to try again with the remaining seeds. But only if I can stop them dying this time!

Can you help?

Answer
The white on the top of the soil is most likely mold so the soil must be staying too damp.
This could mean that the pots they are in are too large which would cause the soil to stay too wet.
and/or
You may be watering too frequently.

Before watering stick you finger into the soil about an inch.  The soil should be just barely damp.  

Most seeds (including basil) do best when started in smaller containers.  You may want to check my recent blog post: http://gardeninspire.com/2013/02/13/three-seed-starting-methods/

Be sure to use a seed starting mix or compressed pellets.  Do not use garden soil or potting soil.

After the seeds have sprouted, if there is more than one seedling per container remove all but one by cutting the extra seedlings off right at the soil surface.  

When the remaining seedling has 6- 8 leaves transplant it into a larger container - but not much larger - a 3 - 4" pot works well.   Once it grows larger you can transplant it again but never increase the pot size by more than 1 - 2".  Or you can plant it outside once the temperatures stay above 40 F and the soil is at least 60 F.


There is also the chance that your basil has the disease mentioned in this article http://www.garden.org/foodguide/browse/herb/annual/1234
Basil likes warm temperatures and light so be sure it is getting these conditions.

You can also begin harvesting leaves once it has at least 6 leaves.  Just cut the plant back to right above the first four leaves.  This will cause the plant to become bushier and produce more leaves than it would if you did not cut it back.  The leaves you removed can be put in a salad even if they are small.