The Jerusalem Botanical Gardens has a number of Musa sp. plants, waiting to move into the new tropical glasshouse. Due to their size and location, the Musa’s haven’t been repotted for several years. The resulting plants have root balls so dense little actual soil remains in the pots. The aim is to have fresh, vigorous, healthy plants ready for planting in August.
Musa sp. are a compliant genus to work with. Whether you trim the roots or stems as long as the plant is in growth it tend to cause little suffering. Of course after any trimming plants should receive water and food. As I am root pruning I will be changing the compost mix anyway.
I also changed the plastic pots for a large hessian bags. Bags are easy to handle and will make it much easier to move and position the plants in the new tropical house. I do worry about bags rotting, nothing is worse than the handles of a heavy plant bag tearing. The planting should happen in August though, so no chance of rot before them.
The potting medium is 2:1:1 Coir:Tuffa:Perlite with Osmocote. It has a fairly high air porosity for maximum rooting, whilst not drying out too quickly. The glasshouse gets up to 40 Degrees Celsius in summer so rate of drying is always an important consideration. I didn’t use a huge bag as the plant only has a few months pre planting and I want the root system to have just about filled the bag by then. If planting can be timed just as the plant is ready to move on that would be ideal.
Below are some photos of the process. You can see just how much root mass was removed. I also removed 50% of the foliage (oldest leaves first) to reduce transpiration. The roots are cut yo a variety of lengths to encourage rooting throughout the bag. Cutting the roots in a long at the base leaves plants with young roots only in the bottom of the bag.
The picture above shows how stressed the plant is. I took it outside to repot it just so I had space to work.
The rooots have filled the pot. They have then wound around the pot, a process called girdling.
The plant is then layer on its side to remove the pot. If you have two people this can be done whilst the plant is standing, assuming your partner can lift it.
Rootsgrowing through the pot are cut away to aid pot removal.
After removing the pots it’s clear how poor the condition of the rootball is.
Girdling roots are cut out and separated. The roof structure is teased apart, much like separating knotted hair.
Roots are trimmed to different heights, in total I removed around two thirds of the overall root mass. For less hardy plants less roof should be removed.