Wood ash and water make lye, a very caustic substance that can burn many organic materials, so just that should be enough to stop anyone from adding wood ash to a planting hole. The question should not be is there anything detrimental to adding wood ash but rather is there any benefit to doing that, and since there is really none adding wood ash would not be a good idea.
Maybe, possibly if what might be in that wood ash is needed by the plant at some point in the future, after a good reliable soil test shows they are needed, then you might.

Wood ash is a good potassium source but it takes time to become available to the plants. I would suggest incorporating it into the soil a month or so before planting, or try what I do. Everytime I clean the sahes from my fireplace during the Winter, I just stroll out to the garden and broadcast them over each bed. By the time Spring comes, they have migrated down into the top layers of soil and are ready to do their thing!

Ron
The Garden Guy
http://www.TheGardenGuy.org

I have potassium deficient soil and coincidentally had a couple of large pecan branches fall down after the Santa Ana winds. I read that hard wood ash makes K available to the soil, but rather slowly. I was going to use the pecan wood branches in cooking and put the wood ash in my compost, to try to raise the K level. Is that not a good idea? How long should I give the compost? or should I add the ashes directly to the soil in small amounts? Thanks for any information.

I don't know much about pecan wood ot it's ashes. Never saw one here on Long Island. I always add my ashed right to the soil and get good results.

Ron
The Garden Guy
http://www.thegardenguy.org

Cabarita,

Wood ash is a bad choice for your soil because it will push the pH higher than it already is.

You mention the Santana winds. So I'm assuming you're in SoCal. There, the soil is generally near neutral. Any higher pH and your plants are in serious trouble.

Beyond that, why do you think your soil is low in potassium? Did you have a professional soil test done?

Jean
who previously gardened in Long Beach, CA, for 30-some years

There are many people that have taken a little bit of information out of context and applied that erroneous information wrongly. Wood Ash does not contribute any significant amounts of nutrients other than Calcium Carbonate which will raise the soils pH maybe too much so all they other nutrients that you might get from the ash are not available to the plants. In small quantities in some soils adding wood ash may be beneficial but the only way to know for sure is to have a good, reliable soil test done before adding any.

Here is a link that might be useful: Wood Ash in your soil

Wood ash contains about 10 percent potash, 1 percent phosphate and trace amounts of micro-nutrients such as iron, manganese, boron, copper and zinc. The average ash is equivalent to a 0-1-3 (N-P-K). It raises pH in acidic soil, does contribute nutrients to help balance and increase soil condition and overall health and has been used as a soil ammendment for hundreds of years.

Ron
The Garden Guy
http://www.TheGardenGuy.org

Thanks for the comments....they were helpful.

I don't know where anyone would get the idea that the potassium (potash) is only slowly available from wood ash. It is virtually instantly available as it is in a highly soluble form in the ash (K2O which instantly becomes KOH, a type of lye [as mentioned above], when wetted).

Hello end3...my soil tends to be slightly acid here in southern Maine. I add wood ash from a wood stove and a fireplace to my garden beds every year...and lawn area if the winter has been very cold and I have more then I need for the beds. I usually don't test the soil in my beds or lawn...but go by how things look and grow. I use compost...peat moss...spread over the beds in the spring...and fert. with fish/seaweed combo from Neptunes Harvest about twice a month. Franklin

My neighbor added HUGE amoumts of wood ash for many years to one end of their garden. That end is highly the most fertile end of the garden.

If you add wood ash to soils that tend toward being acidic, those soils east of the Mississippi because of the amount of rainfall we usually get, because the amount of water tends to wash nutrients out of the soil you could correct a problem that does need to be corrected. However, if someone lives in an area of low rainfall that does not get nutrients washed out of the soil and that tends to be alkaline adding wood ash to that soil will not correct a problem but will instead make the problem worse.
No moatter where you are it is always a good idea to have a good, reliable soil test done to see if your soil actually needs what you intend to add. One of the problems that people that simply put lots of synthetic fertilizers on their soil is lush growth that is very attractive to insects and pests which means they need to spend even more money on controls for them. If one properly applies good organic gardening practices then their soil will be good and healthy and will grow strong and healthy plants that will tend to be less attractive to insect pests and plant diseases.