Possible Clues:

• Shrub about to be planted in a cold American state
• What'll we hear?
• Thorny shrub with yellow or white-flowers
• It takes twice a century for it to start to grow
• On both accounts, I get a plant that likes sun
• Tree (wattle or robinia)
• Having mechanical sex with accountants, raised plant
• Garden shrub, also known as wattle
• That's a double century and a single A for a tree
• Area agents maintaining air-conditioning plant