My Banana Leaves are turning black

Discussion in 'Outdoor Tropicals' started by Yo_Jo, Jul 4, 2019.

  1. Yo_Jo

    Yo_Jo Active Member

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    I bought a banana plant from Costco for $20 about 2 months ago and I had dreams that it would turn my deck into a nice oasis but I have been chopping off blackening leaf after leaf. The leaves seem to start out in good condition but start to blacken after a week. Is this a problem of too much water, too little water, not enough sun or is this the same issue I am seeing on the Haskap Berry plant right next to it?

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    Last edited: Jul 4, 2019
  2. Sulev

    Sulev Active Member

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    Bananas like warm and moist weather and a spot that is exposed to full sun. Optimum temperature is ca 30°C (85°F to 90°F). Below 15°C their growth stops. They need plenty of water too, if your potting mix has good drainage, then it is impossible to water too much. Though, more than 2 inches per week is not necessary for such a small plant. I think that it is too chilly out there. Maybe something like heated propagation bench under the pot would help. Tropical plants may have root problems (may not obtain water and minerals from the soil), if the soil is too cold for them.
    Bananas are very sensitive to saltiness of soil. So keep this in mind, when fertilizing your musa - too much mineral fertilizer can kill the plant!
     
    Last edited: Jul 4, 2019
  3. Margot

    Margot Well-Known Member

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    I am not knowledgeable about growing banana plants here on the Lower Mainland and on Vancouver Island except to say many, many people do so successfully.

    Here is one example: Abbotsford goes bananas as plant bears fruit in hot summer
     
  4. Yo_Jo

    Yo_Jo Active Member

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    Thanks for the info Sulev and Margo (I want to grow one like Mr Flavelle did in his back yard). It's been a pretty on and off summer here in Vancouver with most people still wearing hoodies during the day - we call it a heat wave if it hits 30c for more than a few days over here.
    When we got it, I placed in into a planter with a mix of 3-1 potting soil/manure I used for growing veggies. After a month my wife has been fertilizing it with with the standard 15-15-15 mix every 2 weeks so if it only needs 2 inches of water per week perhaps the daily waterings are too much for it to handle.
     
  5. Margot

    Margot Well-Known Member

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    As I said, I'm no expert growing bananas but I can't help but wonder if you are over-fertilizing it. What do websites say about how to grow bananas (Musa)? Maybe you should review your cultural practices for clues about why the leaves are discolouring. Keep in mind too that you've only had it for 2 months so it is likely still adjusting from the ideal growing conditions it enjoyed before arriving at Costco to real life for it now on your deck.
     
  6. Sulev

    Sulev Active Member

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    Even in the same Vancouver Island, the microclimate varies considerably. The summer of the current year might be chillier than usual, and affect more those plants, that have unfavourable microclimate. At least according to the weather forecast info there is only 16...19ºC today (and similar was yesterday), that is pretty much lowest suitable temperature for banana plants. I am sure, that among those, who tried to grow bananas in the Vancouver area, there are plenty of those, who failed.
     
  7. Sulev

    Sulev Active Member

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    30ºC is optimum. Anything above 25ºC and below 35ºC is very ok for banana. But as at below 15ºC the growth stops, then even temperatures from 15 to 20ºC may cause lot of stress.
    Too frequent watering might be problem if your potting mix is not well drained. In their natural habitat bananas have frequent tropical rains. I think, it is best to avoid cold tap water.
     
  8. Yo_Jo

    Yo_Jo Active Member

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    I wanted to report back that after not watering it for 4 days the blackening seems to have slowed down. Since you mentioned that it only needs 2 inches of water per week I was most likely over watering that plant. Thanks.
     
  9. Tom Hulse

    Tom Hulse Active Member 10 Years

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    Hi Yo Jo. :) What kind of potting mix did you you use? I see a lot of big bark chunks in there... bark & wood in the mix are not great for bananas. It limits nitrogen uptake, which they need a lot of. Your leaf pattern honestly looks like potassium (the "K" in NPK) deficiency, which bananas need a LOT of also. Nitrogen, phosphorus, and even other mineral deficiencies can severely limit how much K the plant can uptake from the soil. Cold temps can limit that uptake also, like Sulev mentioned.

    I would keep at it and expect to get better results within a month as the night temps warm up and your minerals in the manure become more available (was it composted manure?). I would consider switching to a very full spectrum water soluble fertilizer instead of just an NPK. Maybe roughly a schedule like water twice a week (or only as often as the plant really needs it) and fertilize half strength every week. You could plant some of those annuals right in the banana pot as a watering guide. After they become fully established, when they wilt tells you it's just past time to water.
     
  10. Yo_Jo

    Yo_Jo Active Member

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    Thanks for the reply Tom. Now that I am thinking about it, when we bought the banana plant we also got the gigantic bag of bark much soil from Costco so perhaps we did not use any soil/manure since that load was delivered a month after we bought the banana plant.
    I do have 40 litres of soil with chunky cow/horse manure in 4 to 1 mix (we used that for our vegetable patch) that I can throw on it. Would that help with the potassium? I also have some of the standard water soluble tomato or plant food fertilizer mix.
     
  11. Tom Hulse

    Tom Hulse Active Member 10 Years

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    Ouch! That makes a lot more sense. That leaf patterning is exactly what I would expect trying to grow in straight bark mulch. "bark mulch soil" is kind of an oxymoron, since the whole purpose of mulch is to get plants to NOT grow their roots directly in it. That's how it keeps the weeds down while letting the larger plants reach below it into the non-mulch layer to thrive. Real soil is just the opposite.

    At this point you could either topdress with a soil/aged-compost mix and keep fertilizing lightly frequently, which should be fine; or it's early enough in the year where you could repot into a better soil. Repotting is really tempting, but it would set the plant back and may put you overall behind at the end of the year. I would probably only repot if the plant had a very full, tight root ball in there that could be just plunked into a bigger pot without disturbing it much. I use 50% aged chicken manure with a peat-based good-drainage soil mix to pot up bananas, Brugmansia, and many annuals in the spring. It's like nitrous for your plants. :)
     
  12. Yo_Jo

    Yo_Jo Active Member

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    If you think my banana plant's potassium is an issue what are your thoughts about adding wood ash to the soil? I am smoking a beef brisket and I am going to have several cup fulls of wood ash left over. A mixture of Apple, Cherry, and Mesquite?

    Will it help with the blackening leaves?

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  13. Yo_Jo

    Yo_Jo Active Member

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    This winter was pretty cold and wet. I tried to save the banana plant but the stump got all mushy and I had to hack it off.
    I was wondering if the stump will grow back or is it completely dead. The center 1/2 inch spiral bit seems to be new so I wasn't sure if that was part of it decomposing or it was trying to regrow. (I tried to upload the picture of it but its in HEIC format)

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  14. lorax

    lorax Rising Contributor 10 Years

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    The meristem (the very centre spiral part of the stump) is the part you need to watch - if that tissue is firm and pale yellow to green then there's still life left in the corm and meristem and there's hope for the plant. If it's grey, brown, or mushy to the touch then it's not going to survive.

    If it's pushing growth - if that centre portion of the meristem continues to grow upwards, then it's survived and will gradually shed the outer tissue naturally.
     
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  15. Yo_Jo

    Yo_Jo Active Member

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    Thanks Lorax for the information.

    Originally my wife wanted me to dig the root out and put it out with the yard waste so she could reuse the planter but I resisted. I was really surprised to see the green stem shoot out over the last few weeks and look forward to see how many leafs it can produce before winter comes around again.

    Not sure if it likes it or not but I have been dumping some of my coffee grinds in the planter. French Pressed SB Italian Roast.

    Growth from Apr 20th to May 8th. I think there is new baby shoot coming out of the ground too.

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  16. lorax

    lorax Rising Contributor 10 Years

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    That's very encouraging! It means that the corm wasn't completely frozen, just the above-ground parts of the meristem. The baby shoot you see is a pup - and that's an awesome sign because it means that the corm feels healthy enough to not only push up new growth on your original plant but also to reproduce.

    Don't go overboard with your coffee grounds - bananas like slightly acidic soil, but not too much! Since the weather is finally starting to improve (well, for you anyway - winter is lingering in Ontario) you should probably think about fertilizer. Bananas are heavy feeders - a balanced fert will help it grow faster and stronger.
     
  17. Tom Hulse

    Tom Hulse Active Member 10 Years

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    Congrats on your new shoot!

    Here is a 2016 study you might be interested in titled "Applying spent coffee grounds directly to urban agriculture soils greatly reduces plant growth". It seems that coffee grounds tie up the nitrogen (which bananas reeeeeally need), making it less available to your plant; and the caffeine has phytotoxic effects, reducing growth.

    You asked earlier about wood ash. It can be valuable in small quantities if you have soil that is far too acidic, since wood ash is very alkaline (caustic even), but that type of soil is rare, and more often any beneficial effects of getting some phosphorus & potassium are outweighed by possibly messing up your pH and possibly creating salts and lye if it is added too fast.

    I would love to see more photos this year as it grows back. Keep us posted!
     

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