From Bananas Wiki
What is pH
We speak about a low pH when the soil contains a high level of hydrogen-ions(H+). The more of these ions ,the more acidic the soil is, and the lower is the pH. With less of these ions, the pH of the soil is higher. The pH-scale goes from 0 to 14, where pure water has a pH of 7, we call this neutral. So lower than 7 is acidic and higher is base, or alkaline. Soil with a pH of 4.5 is 100 times more acidic than a soil with a pH of 6.5. Soil with a pH of 4.5 will lack a lot of elements needed for healthy growth. Earth that has a lack of organic matter needs an extra 0.5 pH. So if a plant needs a pH of 6 in a sandy soil (low organic matter), you actually have to bring the pH to 6.5 With certain pH levels, some elements needed for growing are in the ground, but not available for the roots because they make connections with other elements. This will cause diseases.
- Problems with a low pH
lack of Phosphorus(P) - bad growth especially young plants
lack of magnesium(Mg)
lack of molybdeen(Mo) especially in potting soil
To much mangaan(Mn), aluminium(Al) and iron(Fe) wich can poison the plant.
Loss of Kalium(K) and magnesium(Mg) due to watering
On clayground it causes a bad structure of the soil
- Problems with a high pH
Several diseases because of a shortage of Iron(Fe), mangaan(Mn), borium(B), copper(Cu), zinc(Zn) The organic humus will disappear more quickly especially on sandy soil.
- Optimal pH (H2O)
For sand = 6.3
For clay = 7.2
Sand is in spring earlier warm than any other soil but because of its structure it will dry out very easily. The soil contains very little nutrients and often is acid. To improve the quality and the live in the soil it is good to add compost and manure year after year just below the surface.
Clayground gets hard when dry and also contains less oxygen. When there is a lot of rain, the roots will stand in the water and die or will suffer for diseases. When you make a planting hole you can add sand and compost but you must make sure there is good drainage at the bottom of the hole because water from the surrounding area can fill the hole and than you achieved the opposite from what you wanted.
Mix sand and compost trough the ground for a better structure.
Potting soil can contain several different materials which either make it acid or base. Some potting soils stay wet for a long time and those are usually not the best. Normally, the soil contains a fertilizer for a period of 6 weeks. See also Info:Fertilizer The soil must have a good drainage, so it's good to mix some perlite in with the soil. Some people also mix some extra compost through the soil but this can make it more acid, depending on whether there's enough lime in the compost or no lime at all. Be aware that the water can leave the pot easily at the underside. The pH of the soil should be at least 6. Last but not least, the bigger the pot, the better it is for the banana.
pH of the soil
For most bananas and plantains, the pH has to be between 5.5 and 7.5. It is known that a very low pH will result in bad growth and deformed plants.
It has been said that the Ae Ae banana prefers a moderately acidic soil.
For Ensetes, a soil that has a neutral pH or higher is the best. For most Ensetes (and maybe all of them), we know that they grow in a limy environment. (perrieri/glaucum)
How to change the pH
- To raise the pH you have to add lime to the soil and bring more air into the ground by spitting.
Liming will also improve the structure of the ground.
Add 4 ounces of hydrated lime per square yard in sandy soils
Add 8 ounces of hydrated lime per square yard in loamy soils
Add 12 ounces of hydrated lime per square yard in clay soils
Add 25 ounces of hydrated lime per square yard in peaty soils
- To lower the pH
If your soil needs to be more acidic, sulfur may be used to lower the pH if it is available. To reduce the soil pH by 1.0 point, mix in 1.2 oz of ground rock sulfur per square yard if the soil is sandy, or 3.6 oz per square yard for all other soils. The sulfur should be thoroughly mixed into the soil before planting. Sawdust, composted leaves, wood chips, cottonseed meal, leaf mold and especially peat moss, will lower the soil pH.
How to test the pH
Many good garden centers will gladly test the pH of a soil sample for you, or you can buy an inexpensive pH test kit at most nurseries or hardware stores. These test kits generally consist of a test tube, some testing solution, and a color chart. You put a sample of your soil in the tube, add a few drops of test solution, shake it up and leave it for an hour or so to settle. The solution in the tube changes color according to the pH of your soil. Compare the color of the sample with the color chart that came with the kit. Matching colors will tell you the pH of your sample. The better kits will also come with advisory booklets about how to interpret your results.
I started experimenting with different soil mixes after losing several special plants this year. Used 6 pups of dwf orinoco in a "lab experiment" - have so many of them any loss won't matter. Potted one 12 to 18 inch pup in 6 pots containing the following with results noted:
Top Soil, cheap bagged stuff from H Depot -- worst drainage -- slowest growth
Miracle Gro garden soil -- poor drainage -- slow growth
Miracle Gro potting soil -- medium drain -- medium growth
"Sand muckage" from my garden area, local soil -- medium drain -- better growth
Pure peat moss, pearlite added -- good drain -- good growth
Overburden soil mix -- fast drain -- fast growth
Concluded that Overburden was the best for shocked mail order bananas and other plants. It has sand, bark chips and pearlite for drainage,as well as compost for nutrients. All the above test plants were thoroughly watered with regular strength Peters 20-20-20 fert after potting. They were placed on a rolling cart in the south facing porch area just short of direct sunlight.
That way, no extra water from rainfall, and no further watering or fert until significant drying out. Also, spray for mites and c-pillars as needed. Sickly plants will be attacked.
Guess what, using overburden soil and the above method -----saved the Siam Ruby, the Ae Ae and the third go around of ensete Maurelii. As well as most of the G Nain x Sumatrana pups and the original Red Iholene (which pupped after 2 months from a dead mother corm). Thanks to Jon in San Diego on that one.
Overburden soil mix is made for and sold at Bushel Stop.
I would recommend starting a compost pile. I mix mine 70% soil(good soil) and 30% compost and sprinkle in a lot of Osmocote. You can use a lot even more than recommended and it will not burn your plants. I would also place some dry leaves in the bottom of the pot, it helps hold in some moisture.