My brother's had this banana plant for several years. Lets it sit outside during the warm summer months and puts it in front of a sunny window during the cold months. He says it always bounces back every summer and looks good. But he's never fertilized it, and he's wondering what type of fertilizer it might need. Any recommendations? Are there organic products that would work for this?
Those do look underfertilized. On my potted bananas I use Osmocote15-9-12 and some occasional liquid MG. Bananas are heavy feeders. In the ground in the GH I have best results with 1/2 can of 10-10-10 plain fert about every 6 weeks in the summer.
The other problem you have there is soil compaction. You see how low in the pot the soil line is? I'm sure they were not potted at that level. Rather, the soil has compacted and sunk well below the top of the pot. This reduces aeration and reduces healthy root function. The soil needs to be well-aerated. I don't know that it looks crowded, but it surely does need to be repotted. I would pull it, wash out all of the old compacted mix from the edges and bottom, and replant with a loose, well-aerated potting mix. If it will stay in the pot for more than a few months, I would stay away from a peat-based mix like MG potting soil and rather go with a large particle bark type mix that will not compact so readily.
Can your recommend a potting mix that isn't peat based? Most of what I find around here is peat based, but I'd like to find a better mix for my houseplants and for this banana plant. For the health of the plant as well as for environmental concerns.
I could mix my own, I guess, but haven't really figured out what the right mix is. I tried tapla's container mix (from the Containers forum), but it drains so well that you need to water almost every day. The pine bark I used, though, might not have been small enough. I'd appreciate any suggestions for a good potting mix.
You have to make it. I use a variation of Tapla's mix. The key is getting the right size pine bark. I have also substituted coconut husk chips (CHC) for the pine bark which, for the most part, works OK. See posts CHC preparation if you do this.
Epsom salt (magnesium sulfate heptahydrate) is basically magnesium sulfate (MgSO4) attached to seven water (H2O) molecules. It is an excellent fertilizer, especially if the fertilizer you are using does not contain magnesium. Epsom salt helps to correct a magnesium deficiency in soil.
Because of the sulfur in the salt it is great for hard-panned, heavy clay, and alkaline soils. It does not build up in the soil. The only way that it can be deterrent is if your soil has an excessive amount of sulfur in it.
As potassium and magnesium work together in a plant's metabolism it is good to feed to your plants in conjunction with potassium fertilizers.
A very good fertilizer is K-Mag, which is a mixture of potassium sulfate and magnesium sulfate.
The only down side of using Epsom salt is the expense compared to other fertilizer.
To apply Epsom salt as a fertilizer for your plants, liquefy one tablespoon in a gallon of water, and water your plant with it. Don't use Epsom salt to replace a balanced fertilizer, but use it as a supplement.