Re: Just bought a truly tiny musa banana tree, help please! Totally green.
Bananas are heavy feeders on nitrogen and potassium. This what the 'banana food' is or should be. I don't use it. For plants this small, general fertilizers (aka: 10-10-10 or similar) will more the supply the needed nutrients. ... It is hard to over water or over fertilize bananas if the plant is in well drained soil.
I would re-pot to an 8 inch pot (not too heavy to move round) with potting soil which usually includes slow release fertilizer. Then supplement the fertilizer every 10 to 14 days with a small amount of liquid (1/8 to 1/4 cup) fertilizer for a quick boost. Miracle Grow or similar is a high nitrogen fertilizer... Water if the top of the soil is dry. Depending on the soil mix, the amount water used will vary. If you see water running out of the pot bottom, then it is too much because the water is washing out fertilizer nutrients.
Next light ... Usually we don't know the lighting condition the plant was use to when acquiring a new plant. Bright direct sun light can burn a young plant. So, let the plant get bright light but not direct sun; not very long anyway. Then as new leaves grow slowly give more direct sun light as it hardens off and grows.
Good luck ... just tend to your BABY until it starts growing and becomes accustom to your location.
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