How to Add Wood Ash to Potted Plants to Raise the PH

Wood ash is a source of potassium, phosphorus, magnesium, aluminum and many micronutrients required by plants, although the amounts vary depending on the type of wood burned. Because wood ash is also quite high in calcium carbonate, adding it to soil will raise soil alkalinity. A soil's pH is an indication of how acidic or alkaline it is. Most plants prefer a slightly acidic soil, with a pH of 6.0 to 7.0. Many nutrients are more easily absorbed at that level.

Fork
Large dry container
Soil pH kit

Instructions

- 1
  Measure the pH of the soil in your potted plant using the kit. To a highly acidic soil, with a pH less than 5.5, add 1 lb. of wood ash per cubic foot of soil. To a slightly acidic soil, with a pH between 6.0 and 6.5, add 0.4 lb. of wood ash per cubic foot of soil. If the pH is neutral or alkaline, with a pH of 7.0 or greater, trying to raise the pH is generally not recommended.
- 2
  Use a fork to loosen as much of the soil around the plant as possible, taking care not to damage the roots.
- 3
  Grab the base of the stem of the plant, and carefully lift the plant out of the pot. Shake off into the pot as much of the soil from the roots as possible, taking care not to damage the roots. Place the plant next to the pot.
- 4
  Pour the soil from the pot into a large dry container
- 5
  Measure out the required amount of wood ash, based on the pH level of the soil, and mix it thoroughly into the soil.
- 6
  Pour a small amount of soil back into the pot, enough to have an inch or two of soil on the bottom.
- 7
  Grab the plant by the base of the stem and place it in the center of the pot, on top of the soil.
- 8
  Pack the rest of the soil around the plant.
- 9
  Water the plant; this will help the wood ash react with the soil.

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