Are Pet Ashes Good For Plants?

When we lose our beloved pets, many of us want to return them to nature by placing them in the garden. Many of us want their final resting place to be the place they roamed, played, and in many cases helped to dig (at least that was my case. My beloved Pancho often helped by digging holes in the garden when we were gardening). But will placing the ashes in the ground damage our living memorial spot? 

Are pet ashes good for plants? The answer is no; Cremation ashes may be harmful when placed in the soil or around trees or plants in high concentrations. This is because ashes contain high concentrations of calcium and increase pH levels in the soil. Too much calcium in the soil can quickly reduce the supply of nitrogen and may limit photosynthesis. High pH levels in the soil hinder soil bacteria and structure, and nutrient leaching and availability.

But this should not deter you from getting your furry friend back into the ground. There are ways to do this without damaging your living memorial spot.

Below I describe why pet ashes are harmful to plants and trees, and provide alternatives to placing the ashes in the ground so you can still create a memorial spot for your best friend.

Why Are Pet Ashes Harmful To Plants And Trees

For most plants, the optimum pH range in the soil is from 5.5 to 7.0. However, ashes in high concentrations can increase pH levels higher than 7.0. This, as stated above, can change soil bacteria and structure, nutrient leaching and availability, and photosynthesis activity. In other words, concentrated amounts of ashes are similar to putting too much fertilizer on the same spot. 

For cremation ashes to become beneficial to plant life, the high pH level has to be lowered and the toxic levels of sodium must be diluted. If these two concerns are not properly addressed, the plant will become stressed. 

To lower the pH levels mix the cremated ashes with compost, manure, organic nitrogen fertilizers like alfalfa meal, soy meal, or cottonseed meal; or coffee grounds. Yes, you read correctly coffee grounds, or even better cold weak coffee helps to reduce pH levels in the soil. This is because coffee is acidic, thus counteracting the alkalinity in the ashes. 

The usage of coffee grounds/cold week coffee is especially effective in potted plants, house plants or vegetable gardens. Be aware, strong coffee or the usage of this every day will hinder the plant. For best results mix 1/4 cup of coffee and 3/4 cup of water in your mixture (depending on how strong you brew your coffee), and use it only once a week.

Mixing your pet ashes with compost, manure, organic nitrogen fertilizers or coffee grounds/cold weak coffee, only lower the pH levels by small amounts (half of point to be exact).

To lower soil pH by larger amounts (more than half a point). I would get a little elemental sulfur on Amazon to use.

Whichever you select ensure you mix the compound thoroughly into the soil, otherwise the pH levels will be decreased in small spots rather than the whole area. Be aware that the Sulfur compound only works during the summer, when the soil is warm and bacterial activity is at its highest.

However, as per the usage of compost, manure, organic nitrogen fertilizers or coffee grounds/cold week coffee, Sulfur can take 90 to 120 days to lower the pH levels in the soil as all of these components rely on the soil bacteria population to increase. 

Unfortunately, there are no quick fixes to lower the pH levels in the soils, so if putting the ashes in the ground is your desire option we suggest:

  • To do it in the summer, 
  • To wait at least 120 days, test the pH levels in the soil to ensure they have reached 5.5 to 7.0. This website gives a comprehensive guide on home kits to measure the pH levels, and 
  • Wait weeks or even months before you plant the tree. The last thing you want is for the tree to get damaged.

However, putting the ashes directly in the soil is not the only way to memorialize your beloved pet. Below are other ideas on what to do with the ashes 

Alternatives To Burying The Ashes Directly In the Ground 

If your desired option is a memorial garden without having to wait for 3 to 4 months before planting the tree/plant or having to worry about the pH level in the soil; consider putting the ashes in an urn and burying this.

Biodegradable urns

Biodegradable urns are specifically crafted to decompose with time.

There is three types of biodegradable urns:

  1. Biodegradable burial urns. These urns are designed to bury the ashes only. No tree or plant will grow from these. if using a biodegradable urn, consider planting a tree with it, or adding a memorial plaque, rock, marker or bench, so you know where the ashes are buried. We wrote a guide on the best biodegradable urns in the market.
  2. Biodegradable tree urns or living urns. These urns are often made from natural plant fibers and allow you to grow a plant/tree in memory of your pet. 
  3. Water urns. These urns are designed to decompose in water. This decomposition can take between 1 to 30 minutes. 

Whichever option you select ensure to remove the ashes from the plastic bag as this will not decompose, instead consider using the biodegradable bags that comes with the urn.

Nondegradable urns 

These urns do not decompose with time or grow anything from the urn. 

If you are using a non-degradable urn it is advisable to dig a hole deeper than 2 feet (60 cms) to minimize the chance of disturbance. 

For nondegradable urns consider something that is sturdy and durable as the urn will be tested against very harsh conditions. 

Depending on your budget generally, the best options are stainless steel, marble or granite urns. However, If you want a wood, ceramic, metal or glass urn; and you want to protect it from the elements consider using a protective burial vault. These are made from polystyrene or reinforced metal.


Creating a memorial spot for your furry friend is a great way to memorialize them.

However, high concentrations of ashes can have an impact on the tree/plant you bury as these will increase the PH levels in the soil.

To avoid any disappointment, either use fertilizer to reduce PH levels or use a biodegradable urn.

If using fertilizer ensure you measure the PH levels in the soil before planting, to ensure these are optimum for the tree/plant.

Carolina Pieters

I'm Carolina and created this blog, to provide practical advice and emotional comfort for those dealing with pet loss.

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