Do not drown them, they are susceptible to root rot and excessive moisture water will only increase the odds in favor of the root rot. Trees that have been subjected to frost are also more susceptible to root rot.
Well drained fertile soils are best . Babaco will not grow in seaside or salty locations.
Apply high nitrogen fertilizer during the growing season, and switch to a more balanced fertilizer just prior to fruiting.
For an optimal quality yield the tree should be pruned to allow only the healthiest single trunk to grow and produce. If you do not prune it - you will still get a fruit yield - probably more so far as quantity is concerned - but a much lower quality of smaller fruit.
New shoots will periodically form around the plants base, these should be removed during the plants fruiting season. At each seasons end the shoot that produced this years fruit should be cut down to a stump, and a new shoot permitted to mature to take its place. Don't trim back the producing stem till a new shoot emerges.
Babaco is susceptible to fungal diseases , not the least of which is root rot - as was previously mentioned. It is also susceptible to powdery mildew.. Insects such as mites and slugs are known to feast on this plant - precautions should be taken.
Even though it is not not a native species, deer for whatever reason, are very fond of babaco and will devour any plants they come across.