Question
We planted a 2 ft. sweet broom plant about 2 years ago. It bloomed and grew to about 5 ft. We live in Chula Vista, Ca. When winter came, all of the foliage fell off. In the spring it didn't come back. The wood is still green but there isn't any foliage. I am having trouble finding out what we have done wrong or should we just pitch the plant.

Answer
Hi Chris,
Thanx for your question.  If the wood is still green I would let it go through this season and see if it starts to leaf out next spring.  If it doesn't, I would dig it up and see if gophers or something got the root system.  This plant can be finicky sometimes before it gets established but two years should have been enough time for it.  It is hardy to 15F and you're near San Diego and I do not recall temps getting that low.  Did you maybe water it too much?  Once established it is very drought tolerant.  If you had a really wet period of time, that is a possibility too for leaf drop.  There is also a pest called genista caterpillar that will defoliate sweet brooms.  Look for 1 inch long brown, thin caterpillars with white hairs.  They often create webbing too.  A related plant called Scotch broom was introduced into California as an ornamental, landscaping plant.  It proved to be very invasive and so the genista caterpillar was brought in to control the plant.  The caterpillar unfortunately, attacks other ornamentals also.  To control the caterpillar use Bacillus thuringiensis (Bt) product, diazinon, chlorpyrifos or orthene.  You might want to take a sample of the shrub into your local county extension agent for examination.  Here's a link to your local county extension offices.  I hope this helps.
Tom

http://cesandiego.ucdavis.edu/