A rant about poor compost

As lots of fellow bloggers have been doing recently, I feel I have to draw attention to how poor much of the commercial compost on sale these days is. Even leaving aside the issue of the weedkiller-contaminated compost with which I had to contend, very frequently the compost seems to be completely lacking in nutrients. Plants sown or planted in it can barely survive, let alone thrive. Look at these little cabbage seedlings, which are now a month old:

By this time, they should be at least twice the size, and they should be a healthy green colour, not yellow and sickly like these.

The trouble is that a high proportion of the content of commercial compost is material that has been discarded specifically because it is no good! Local Councils encourage us all to compost plant matter at home (some councils provide free or heavily-subsidised compost bins), and only to take to the Household Waste Recycling Facility (aka Tip) the material that is too big/tough to compost without being shredded, or is diseased. Is it any wonder therefore that commercial compost is poor? Where are the nutrients supposed come from?

This one mentions NPK and trace elements, but significantly gives no indication of how much of each is present. The patented wetting agent is evidently considered the most important feature. I would have thought that good compost wouldn’t need an artificial wetting agent.

The blurb on this one has all the right words – “peat-free”, “organic”, “recycled”.

But what are “composted timber residues”? Presumably wood!

How long would you expect your compost to provide plants with the nutrients they need? Suppliers of commercial compost evidently expect it to be a short time, probably because they hope you will then go and buy some of their expensive plant-food to replenish the poor compost, as evidenced by this next photo:

 I have seen some multi-purpose composts say that they provide nutrients for only 3 – 4 weeks. Surely this means that the nutrients are added artificially during manufacture and are easily leached out when your plant-containers are watered?

Until recently, most commercial composts used to contain a fair proportion of peat, but it has become politically incorrect to use peat, because this depletes the ancient peat-bogs, a resource that is renewable only in the very long term. But the fact is, peat is an excellent growing medium for young plants. Look at these words “…contains higher levels of peat for a better, more consistent growing medium…”

This puts gardeners in a difficult position. You have to see it in context though: we extract huge quantities of oil and gas from the earth and people seem to consider this to be OK – even “essential” – so how does this differ from extracting peat? What proportion of the population even know what a peat-bog is, let alone considers it essential to preserve? Using peat for growing plants doesn’t pollute the atmosphere like burning oil does either.

There is definitely an opportunity here for an enterprising company to develop compost that does have a good level of nutrients, does not contain peat, and does not consist mainly of discarded household rubbish. What happens, for instance, to all the fruit and vegetables that are rejected by the big supermarkets as being sub-standard or surplus to requirements? We are told they are “ploughed into landfill”. Could they not form the basis of organic compost? What about the husks from maize and sweet corn, consumed in vast quantities by people all round the world? Could they not be used for making compost? There must be lots of things like this that could be used, if only someone thought about it. Anyone know an entrepreneur…?