How to Make Potash; A Necessary Fertilizer

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Potash is a very important fertilizer for plants. Potash allows plants to flower and fruit more productively. It also provides for healthy roots which allows plants to gather more water which is necessary for their survival. The potassium in potash helps to boost disease tolerance in plants. It also helps plants to synthesize sugars which provides the energy they need to grow.

Potash was the first patent ever issued by the United States government signed by President George Washington on July 31st of 1790. That patent was granted to Samuel Hopkins for the making of potash with a new process and a new machine. Potash remains as important today as it did back in 1790.

Potash is made of potassium carbonate. Most of the time, it’s found in rock deposits where ancient inland seas evaporated over millions of years ago, however, potash can be made in a pot with ashes also. In the beginning of the United States, potash was primarily made from wood ash obtained through burning native hardwood trees. The chemical compound potassium carbonate was extracted by leaching the ashes in a pot to dissolve out soluble compounds. Today, we’re going to go over how to make potash at home.


  • Hardwood ashes
  • Wood, glass, clay, or plastic container
  • Water
  • Pot


  1. Collect hardwood and burn down until white ash remains. Hardwood trees include Oak, Beech, and Hickory. An easy way to tell if a tree is hardwood is if it loses its leaves in winter.
  2. After the fire has cooled, collect the white ashes. Sift out any bits of wood and debris that is left behind.
  3. Fill a non-metal bucket half full of the ash once it has cooled completely.
  4. Fill the bucket with water completely, covering the ash. Gently stir the contents of the bucket.  This will allow missed wood scraps to float to the surface.
  5. Let the mixture stand for a minimum of two hours. This allows the contents to separate. Skim off any solids on the top.
  6. Gently pour or ladle the water off the top of the bucket. Filter through a cloth if at all possible.
  7. Take the filtered water and boil it down until potassium carbonate crystals form.


  • In order to get the maximum amount of white ash from hardwood, it is necessary to have many small fires that are very hot. One large fire will produce more charcoal than white ash.
  • Letting the water stand for longer than two hours in the non-metal container will allow greater uptake of potassium carbonate. Letting it stand overnight in some cases may be best.
  • Although this process does produce high quality potassium carbonate (also known as potash), it does not produce a large quantity of potash for the garden. It produces a moderate amount for liquid soap production.
  • In order to produce a large quantity of potash, it may be necessary to repeat this process multiple times. Leaching from the same ash bucket multiple times will yield a diminishing return of potassium carbonate.

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