Blueberries; make your own Ericaceous compost!

Acidic compost for Blueberries, Azaleas & Camelias

I love blueberries. It’s the one seasonal food that I’ll buy in stores whenever they’re in stock. But they’re all imported, they’re often silly prices and often taste terrible … and the variety names and country of origin change so often that it’s impossible to keep track of which are tart, firm or sweet!

Once you’ve bought some blueberry sticks in 9cm pots before you grow them on for a year or two and before they’re planted in the ground or for most people in containers, you’ll need to lower the ph of the soil, but whatever you use doesn’t last so you have to keep lowering the ph to keep them alive and thriving.

There aren’t too many examples of places where acidic soil is well-known. I was on the Azores a few years ago, around towns on the main island the ground is covered in Hydrangeas, blue ones grow in acidic soil and pink ones in more neutral soil. And naturally, on the East Coast of the US, all of the Red Cedar grow in acidic soil and so wild Blueberries grow in abundance - and in the heathlands around Scotland where the heather grows or the peat bogs of Ireland or both Exmoor or Dartmoor in the South West UK.

After you’ve got your soil acidified, adding organic matter to any container acts like a buffer and prevents the Ph changing much, but that will eventually stop working as it’s broken down and consumed and it needs to be added after the soils is acidified.

Coffee grounds are said to be very acidic, but in fact you drink the acidic part and used coffee grounds are so close to neutral, that they barely make any difference.

Pine needles. Don’t bother, just because coniferous forest top soil is acidic doesn’t mean that the subsoil or the needles are acidic and by the time they’re brown and on the ground they’re close to neutral.

Peat used to be the base for commercial ericaceous compost - I live near old peat cutting areas and one of the quirks of English laws is that if you see a mole hill in a peat field, you’re allowed to harvest any of it without permission to be on anyone’s land.

Peat moss or sphagnum moss used to be one of the main acidifying elements that was put into ericaceous compost because it’s acidic, but it soon returns to neutral and like all peat based products, it’s being phased out.

Watering down home made yoghurt and mixing it with Effective Microbes (EM1) or LAB and a little yeast will acidify the soil and bring in tons of beneficial microbes.

Diluted human urine has a ph of 4.5, and is a good fertiliser, so that would work, but a lot of people wouldn’t want to know that you’ve been pissing on the blueberries you want them to try :)

You can feed any acid loving plant with any of the commercial ericaceous plant feeds, but I take microbes over soluble chemicals every day.

Ammonium Sulphate and Magnesium Sulphate (Epsom Salts) can be used as a fertiliser for Blueberries and is usually written on the bottle ingredients.

Aluminium Sulphate will acidify soil, but metals like Aluminium are generally toxic to plants and the process of acidification that occurs in the soil doesn’t require microbes, so it’s not the best choice.

2 Tbs of white vinegar in a gallon of rain water will keep the soil acidity low for most of the growing season, but this has to be done regularly as the artificial acidity will be washed out by rain.

One of my many containerised blueberries in full blossom this morning :)

Big fanfare: Sulphur chips.

One of the best reasons to use Sulphur is that it’s converted through a biological process because the microbes in the soil break it down and turn it into Sulphate, which is essentially Sulphuric Acid when added to water, so the microbes do all the work for you.

I personally use agricultural sulphur chips two or three times a year starting in late winter when the microbes start to wake up again mixed with Blood, Fish & Bone and twice more to keep the blueberries in top shape and the soil around blueberries acidic and filled with microbes.

It’s the same for every other shrub and acid loving plant in the ground. I mix a handful of Blood, Fish & Bone with Sulphur Chips every late Winter around the base so that it can work its way into the soil and start feeding the plants and another couple of times throughout the season.

So, here’s the plan when you want to grow blueberries:

If you’re starting with a 9cm pot and a branching spindly stick, you can grow it on for a year or two before you see any blueberries, but if you start with a 2 litre pot it’s going to produce berries next year, be root bound and will need feeding and potting on.

When you decide to grow any acidic plants, you should plan to make your own ericaceous compost - and you need to make your growing medium a year ahead because it takes the microbes months to break down the Sulphur Chips because until it’s broken down, the ph won’t drop into the acidic range of around 4.5.

For your base medium, you don’t want to use a clay soil, you don’t want to use a heavily organic base either, so you need to start with a loamy substrate - if you need a few hundred litres, you’ll need a large covered container, add the base material, some microbes and sulphur chips, then mix in the bulk of organic matter on planting the blueberries the following year to work as a buffer to keep the ph stable.