Musa basjoo, the Japanese hardy banana, is a fabulous hardy banana, which when given rich soil and plenty of feed can reach 4m or more. It is root hardy so shoots from the ground each year if frosted but if the trunk is protected it gets larger each year. This plant can even flower and produce small though inedible bananas.Plant in moist rich soil in a sunny or partially shady spot and then all you have to do is stand back and enjoy.
For growing outdoors, it is important to understand the requirements for long term establishment. The term hardy banana means that the root-rhizome is hardy and to overwinter it successfully we recommend protecting the trunk with straw or fleece to prevent it freezing. If you do this the banana will start off in the spring where it finished off last autumn. left unprotected the above ground stems and leaves will usually be frozen and die down to ground level. As a rough guide when temperatures fall between 6-4. degrees centigrade during the day growth will stop. Once frosted the leaves will collapse and below minus 3 degrees centigrade the trunks will start to break down. There are all manner of techniques out there for protection and I guess much of it depends on where you live and how severe the winter is but as a rule I like to build a wigwam of bamboo pole round my bananas once the leaves have been frosted and fill the wigwam with straw, winding size string around this to prevent the wind from blowing the straw out. This looks quite wacky in the garden, doesn’t take long and means you can grow impressive size plants each year. Having said this as I write this in mid-March 2020 from my office in West Sussex our bananas here in our nursery garden haven’t been protected at all as the winter has been so mild. What I do like to do for maximum growth is feed the banana plants well. I do this by mulching around the base with rotted farmyard manure, this also help insulate the roots from cold. And top dress with organic fertiliser from April through to August with an organic feed such as pelleted poultry feed.