I have a western exposure that desperately needs some shade. I lost a lot of plants back there this winter. Since then, my croton collection has grown and I am running out of space for them that is filtered sun. My requirements are: Fast growing & gets no taller than 15' due to power lines overhead. Color is not important as the crotons will provide that. I would also prefer that they keep their leaves year round but not a deal breaker. Suggestions?