I would like to plant a ponderosa pine (one gallon size) with my mothers ashes in the Deschutes National Forest. I have already checked with this agency and a permit is not required. If I dig a hole and place the ashes at the bottom of the hole, add fertilizer and dirt, then add the tree and water, will the tree survive? Or, will I kill the tree because of the pH of the cremated remains??? How do I do this?
My condolences for your loss. I appreciate your desire to carry on your mother's legacy by planting a tree and incorporating her ashes.
Cremated remains are not the same as wood or plant matter ash, and are primarily composed of calcium phosphate and minor amounts of other minerals, which can be quite beneficial to plants. I would recommend that you create a big enough hole to incorporate the remains into the soil to avoid too great of concentrations within the young root system. This should be more beneficial to the surrounding soil and benefit the tree as it grows. I would definitely recommend watering it during the summer to get it established and to make sure that it survives. You do not need to apply any fertilizer, but you may want to prep the site by hand weeding a couple feet out from the seedling. Also, avoid planting the seedling immediately next to another tree or sapling, because it will do better if it is not being shaded out or competing for moisture with taller trees.
Please take care that you are not planting the tree where it will not grow well (juniper woodland or high elevation), in sensitive habitats (meadows) or areas it may be removed (close to a trail or an area that is marked to be thinned). A potential alternative if you are worried about the tree surviving, would be to find a nice mature ponderosa (>21 inches trunk diameter) and spreading the ashes around it.