Hi, Charles,
It sounds like your last tree lupin behaved as expected - they are very fast growers but are short-lived. Generally, they require little or no pruning and can be expected to reach 1.5m tall and wide. However, if you want to keep it a bit more compact, you can cut it back by half in early spring. That pruning recommendation is typically given to those who grow it in its native California where winters might be milder than where you live. if you live in a colder area, it might not respond as well to pruning.
Kathy C
Replied: Tuesday 29th of October 2013 07:17 PM