I have two beds where I removed two (approx 6ft wide) large sago palm (cycad) 2 years ago. I then tilled the bed and supplemented it with organic matter - peat and cow manure. I have since planted bulbs (which perform well). The beds drain fairly well and pH is around 6. Occasional fertilizer such as miracle gro. However, any annuals I've planted there seem to languish after moderate growth. Is there something else I need to look for?