How To Kill A Banana Tree Root
You cut down your banana plant (Musa spp.) and thought you had dug out the roots. But new banana plants keep popping up. While products containing glyphosate, such as Roundup, have long been the recommended standard for removing banana plant roots, for home landscapes, the best, safest method — albeit the most labor-intensive — is to remove the roots manually.
Thin a Banana Stand
If your goal is to continue growing your banana plant but ensure its productivity and health, you'll want to remove some of the suckers it produces so that each stem has enough room and can access enough nutrients. Usually not more than two or three suckers should be retained for a single, large stand.
Determine which suckers you want to remove; then cut them down to ground level. Using a sharp spade, dig down into the underground bud, gouging it in the middle. A piece of rebar would also work. Make sure you kill the bud itself or the sucker will regrow. To ensure complete removal, dig down to find the underground rhizomes and cut them out as well.
Banana roots can spread up to 15 feet in all directions, but they tend to be somewhat shallow. If your banana has spread throughout your yard, cut the roots closer to the plant, but be aware that cutting too much root can slow your plant's growth.
Remove a Banana Stand Entirely
If you have a large, mature banana stand, its rhizomes and root system will be quite wide and may also be deep. In this case, think backhoe. Trying to manually remove a clump of bananas with multiple stems and an extensive root system is almost impossible. A professional landscape company will have the right equipment to dig out the entire plant and its root system.
If your banana plant is smaller or a backhoe just won't fit into your yard without damaging your existing landscape, you can dig out the banana using your own muscle power. Grab a shovel and a pickax and get ready to sweat, because this is a big job. First, cut the banana stem down to about 1 foot. Using a shovel or a pick, dig into the remaining stem to break it up and to reach the underground rhizomes. Dig those up as well. Be sure to poke around the stem thoroughly to find the entire rhizome. New banana suckers are known to develop from banana roots, so this will be a broad excavation job to ensure you get as much of the root system as you can find.
Keep a Spade Handy
If, in spite of your best efforts, you see banana suckers continuing to appear, prepare yourself for some regular maintenance. And, unfortunately, this is the likely scenario because banana plants are vigorous and prolific growers, given the right conditions.
Cut the sucker down to soil level, then again pierce the fleshy bud and center of the sucker to kill it so it can't regenerate. Continue to monitor the area for the next several months and remove any new growth. Try to avoid installing any new landscaping in the area until no more suckers appear and you feel confident that the banana plant is indeed just a memory.