It’s still quite cold, and your fireplace is roaring at full tilt. At the tail end of winter, you find yourself with buckets of ash and you’re not sure what to do with it. Yet collecting ashes is a good habit to cultivate, because ash is quite useful for the home, for hygiene, and even in the garden.
Wood Ash Finds a New Use in the Garden
Ash from deciduous trees is generally richer than ash from softwoods. It contains a lot of calcium, in the form of lime (between 17 and 33%), potassium (between 2 and 6%), magnesium (between 2.5 and 4.6%), phosphorus (between 1 and 6%), iron and manganese oxides among others, and other elements like sulfur, sodium, etc., in trace amounts.
The ashes make an excellent calcium-rich soil amendment, capable of replacing lime to neutralize soil acidity (so avoid it on very alkaline soils). Thanks to the potassium, they also help promote flowering and fruiting of plants.
Which Ashes for the Garden?
Prefer ashes from untreated wood. When in doubt about provenance or composition, don’t spread ashes in the garden.
The wood pellets for heating are generally acceptable, but make sure the binders are starch-based and free of additives.
This is not the case with charcoal used for barbecues: some contain potentially toxic products. Only use ashes from charcoal whose source you know.
Using Wood Ashes in the Garden
Also rich in mineral salts, wood ash provides nutritional benefits to your lawn, as well as to garden vegetables and roses.
Regularly spread a handful of cool ashes around your trees and your plantings.
Ash Against Slugs
In addition, fresh ash is a very good repellent against slugs and snails. However, once it gets wet, it loses its effectiveness and won’t be useful: keep it dry. And as you’ve guessed, there’s no need to rely on ashes in wet weather—wait for spring…
Ashes in the Compost
Meanwhile, wooden ashes can, in small doses, complement the compost mix to improve its structure, just like kitchen scraps and sawdust.
Generally, add a good handful each time you add a bucket of organic matter. Scatter the ashes on the surface to prevent clumping.
Attention: Ashes in the Garden – Use With Awareness
Excessive ashes can disrupt the soil and its biological activity. Indeed, in very large quantities, ashes can form a crust that prevents gas exchange between the soil and the air.
As explained above, ashes in the garden should not be used on calcareous soils, and also not on plants that prefer acidity.
FAQ – Wood Ashes in the Garden
Can you put wood ashes in the garden?
Yes, untreated wood ashes can be used in the garden. Rich in calcium and potassium, they act as a natural liming agent and promote flowering as well as fruiting. They should be used in small quantities and only if the soil isn’t already lime-rich.
Which ashes should you use in the garden?
Only ashes from natural, untreated wood (firewood, branches). Wood pellets are acceptable if they contain only natural binders like starch. On the other hand, ashes from treated, painted, varnished wood or certain barbecue charcoals should be avoided.
Are wood ashes good for the vegetable garden?
Yes, in small amounts. They provide minerals useful to vegetables and improve soil structure. A handful around plants or light incorporation into the soil is sufficient. Excess can upset the soil’s biological balance.
Do ashes repel slugs?
Yes, dry ash acts as a natural repellent against slugs and snails. It should be spread when the weather is dry because once it’s wet, it loses effectiveness.
Can ashes be added to the compost?
Yes, but in small amounts. A little handful added when adding organic waste improves compost structure. Avoid adding too much to prevent disturbing the compost balance.
Which plants don’t tolerate ashes?
Acid-loving plants such as rhododendrons, azaleas, hydrangeas, or blueberries don’t appreciate ashes, as they raise the soil pH.
