Spring: Using Potash and Egg Shells

At Pig Row we've had a large Burley stove for many years, and for many winters it has kept the ground floor of the house warm, balmy and positively tropical. It is one of the more environmental stoves (it's 85.5% efficient!) which means we rarely have to sweep the chimney and for us being in smokeless zone (we know, we know, middle of nowhere and still smokeless) is one of the few solid fuel stoves at the time of installation that were DEFRA approved. The stove burns only wood, much of which we forage for nowadays. A great byproduct of this is wood ash. For those of you who burn wood, and only wood in your fires, what do you do with your ash and how can this waste product be of use to your garden?

How to use wood ash in the garden to boost fertility and crops.


Wood ash is full of potassium and if you have pH problems in your soil (like us), it can raise it towards the alkaline end of the spectrum but only as part of a campaign to improve your soil. It can help inhibit such diseases as clubroot in brassicas. The potassium content of wood ash can be up to 3% depending on the age of wood, and you may think that isn't much but remember that potassium is linked with fruiting and flowering in the garden. It's a real beneficial byproduct. The act of burning old foliage and wood in November has largely vanished from our domestic gardens but this too was part of the cycle of growing and provided wood ash.


Wood ash is full of potassium which boosts fruiting and flowering.

When we first moved to Pig Row we had to clear the entire 1/4 acre of ash trees, laurel, brambles and rose willow herb. This meant several large bonfires of wood we couldn't use on the wood burner. It was in these areas that we planted the following spring that we had the greater yields, the highest success rates and the lowest incidences of disease and pest control. Wood ash speaks for itself but here's how you can use it:


  1. Wood ash in small amounts (we tend to add half a bucket) added to a large compost heap will quickly blend in with other materials and help to raise the temperature of the heap (we're not talking hot ash here, it is the bacteria feeding off the wood ash and multiplying that increases the heat). You shouldn't be able to see the ash after mixing in.
  2. Wood ash can be applied directly to the soil in the vegetable and fruit garden garden in late winter or early spring at a rate of 50-70g per sq m (1.7-2.4oz per sq yd). Basically, you're looking at a handful of ash per square yard. You can lightly fork it in or apply before rain.
  3. Some people find it useful to sieve the ash before use to remove debris. This is vital if any of the wood you burn could have nails in them or staples. We don't bother as we wear gloves and you can find any big lumps and break them down or remove them.
  4. Don't apply ash on windy days and avoid breathing in the dust. No ash is good for the lungs.
  5. Ash in some people can cause an allergic reaction so wear gloves. Likewise, wear wellies or boots and work clothes as the ash does get on you. So, do not garden in your finest, a plunging neckline or cummerbund just advertises 'fill me with ash'.
  6. When wood ash is applied frequently to vegetable beds, cutting gardens and fruit it is always recommended that use a pH test kit to monitor changes in pH. pH kits are not expensive and the cheap ones retailing around £1.20 are worth the time and money.  The idea is to prevent levels pf pH going over 7.5.
  7. Wood ash is used where club root of brassicas is a problem. It may not eradicate it completely in it's first year but over time will deter it.
  8. Don't harvest your wood ash and leave it outside in an uncovered bucket as the potassium will easily leach. It can also produce lye. We're not going to tell you how to produce lye, there are plenty of websites out there that do that and you can search for them. We however do have to point out that lye is a dangerous substance and can burn or even blind you if you don't know what you are doing.

8 things you may not know about wood ash.

Egg shells  are 93% calcium carbonate, this is slightly less then garden lime (you can find a complete table of advice on lime and soil types on the RHS website where you can find more extensive information on the application of lime). Lime is good for the soil but it can be scary stuff too for new gardeners. However, egg shells, ground up offer a viable alternative to garden lime. Though it is not as successful as garden lime they're not far behind in growing terms. You can see a report here from Iowa State University on the differences between egg shells and lime in a bid to take a byproduct from the poultry sector into the farming sector. It makes for fascinating reading about soil fertility. We have started to use egg shells on Pig Row for the very reason the report cites, 'to know if the eggshells have any value as a liming source' and the report certainly shows that for small scale growers and small holders that this waste product for years added to compost heaps or used as a slug deterrent, does have a real use in boosting soil fertility. You can grind up egg shells in a blender, but Darren, a member on our Facebook page points out: 'Be careful or they'll dull the cutting edges of the blender!!' Just shows that the page has become a real useful resource to us all. Lisa on the page came up with a solution she uses: 'Put them in a plastic bag and bash with a rolling pin, like you would biscuits, less hassle in the end!!' It's a process we're looking forward to as it gives us time to work out any anger issues we may have after finding ash in our cummerbund and burnt nails in our bra.


The Life on Pig Row Facebook Page is a valuable resource to share solutions.

So what have we learnt? #saveourskills
  1. That wood ash is a useful resource in the garden and shouldn't just be binned.
  2. That potassium improves flowering and fruiting
  3. That wood ash can take your soil from acidic to alkaline
  4. That egg shells are a viable alternative to garden lime
  5. That we should not waste what we have and pay out with money we may not have.
  6. Waste not, want not.

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