The plants I haven't killed yet

My poor sad lavender plant. At first it did really well because this time I read something about it before I planted it. I made sure it had lots of little white things in the soil for aeration and put it in direct sunlight all the time.

But now the leaves near the base are all drying out and the flowers at the top seem to be dry and brownish too. I water it when it is dry like the smart ass at the nursery told me to do. So now what?

I did spray some pesticide on this too because it looked like it had bugs and webs on it like the others. Maybe I wasn't supposed to do that?

Look, it's crying... so sad.