The Ins and Outs of Choosing Bought Compost

Compost is the heart and soul of your garden. Does it matter which compost you buy? Damn straight it does! Well made compost is all our soil needs to grow abundant crops with minimal disease. But rubbish in, rubbish out – compost made with sub-standard ingredients will wreck your soil and your crops. Here are the three key things to look out for when buying compost.

Undercover and in the Shade

Compost is a living product – not that well suited to life in a plastic bag. Once it gets sealed it starts going downhill from there and if it’s sitting out in the weather, especially the sun – it’s speed skiing its way to oblivion. How I’d love compost to be dated. Integrity! Be sure to choose bags stored under cover and in the shade.

Smell

sniff the soil

We’ve all walked past piles of compost bags and recoiled from the smell. Sour smelling anaerobic compost is nasty. There will be no soil life at your place if you put this muck on. Musty smelling compost that’s died and gone to heaven isn’t as dangerous as anaerobic stuff, but a complete waste of money. Trust your nose, my friends and walk on by.

Pyralid Weedkillers in Compost

Clopyralid induced damage in a tomato plant Bezdicek
Clopyralid damage. Photo by David Bezdicek source

I first became aware of herbicide in bought compost in the early 2000’s when a school garden failed to get going. Potatoes sprouted but were curled and distorted. Tomatoes and beans did the same. We presumed spray drift to be the cause until another school garden with the same compost had exactly the same experience but no possibility of spray drift. I started asking questions.

Sounds scary. And it is. Pyralids are a group of persistent herbicides that, if present in your compost, will wreck your crops. It totally deserves its nickname “killer compost”. Bums me out that this spraying is still going on in NZ, but keeping it real, our people are choosing it – so best you are aware.

Clopyralid, Aminopyralid and Picloram are the foes here. They’re used on sports turf, golf courses, school grounds, road sides, hay paddocks, forestry and on home lawns (even though its illegal for home use) to kill broadleaf weeds, thistles, dandelions and clover. Whaaaat dandelions + clover! If only there was an emoji for rocks for brains.

The magic of pyralid and the reason it gets used so lavishly, is that grass and all its relations like corn, continue to grow on nice and happily thank you very much. They are of course saturated in it which is how this stuff lives on in grass clippings + greenwaste, in the manure of animals that graze on grass sprayed with it and in hay from paddocks sprayed with it. It’s so persistent it lives on after the composting process – intensifying in strength even. Yip it lives on and on. 

What’s a Home Gardener to Do? 

makingcompost

Good news is there are producers on the job bringing us pyralid-free compost. All you need do is find them by asking a few simple questions.

  • Do you use grass clippings + greenwaste?
  • Do you use manure from non organic farms?

If either of these answers are yes, then

  • Are you testing for pyralids either with documented grow tests or lab work? And not just once a year, but every batch thank you very much. 

Get asking my friends. Nothing makes change like consumers – you and me and all our friends and aunties (especially the aunties) – getting on the job. 

Let’s keep composters on their toes and let them know that we know. We’re not paying for herbicide residue and soil wrecking compost! We’re growing food … we want good, wholesome compost.

Safe Bets

paranui organics spring festival ediblebackyard nz

Ideally we’d all support our local compost maker – I’ve been using Paranui Organics for over 10 years now. When you find a goody – stick with them.

If you can avoid buying compost in a plastic bag – please do. Not only to avoid plastic, but compost starts dying the moment its sealed up in one. Bagged compost is a very poor cousin to fresh off the pile.

Hit up your local landscape yard and see if you can fill your own bucket or bag. Kudos to the yards out there already doing it – I’d love to hear from you!

If you must buy a bag these 3 companies can be counted on to be pyralid free. Not to say they’re the only ones – just the ones I asked on your behalf.

  • Living Earth were on the job right from the start championing the government to have clopyralid taken off the market. Auckland or Christchurch.
  • Daltons Organic Composts use no greenwaste and test for pyralids. Matamata.
  • Tui Organic Composts are made with 100% organic certified ingredients. Mount Maunganui.

Test the Soil With Seeds

Sowing broadbeans or tomatoes into compost will show you very clearly whether or not pyralids are in the house. A control group of seedlings is sensible so you can compare growth rate and distortions. This is especially useful when pyralid concentration is low and the differences are subtle.

Grow seedlings on for a few weeks. If the compost is poisoned seedlings may not germinate or will grow slowly, be stunted and growing tips will be curled, cupped, twisted – generally distorted, and looking exactly as if herbicide has drifted over them.

How to do your own grow test and pics of affected plants.

Comments

  1. My raspberries were very crumbly this year, and the leaves were full of holes. My bushes are several years old. My husband does prune them, but either in the spring or fall, because we are not here in the winter. Any suggestions to have better berries
    Thank you

    • Could be a few things Marti – either viral if the leaves yellow then crumble, or dry berry if there are reddish blotches on the leaves or even mites if the leaves are mottled. Either way spread good compost at the base of the raspberries. Prune any damaged canes. If you have chooks get them under them to clean up larvae. Foliar spray with Neem and EM and seaweed once a week as a good general baseline for all of the above apart from viral disease. Build beneficial insect population with perennial companions nearby. Pay close attention to the progression of the leaves and canes through the season – photos are a great idea to get a clear diagnosis.

  2. Hi Kath
    What do you do if you’ve got bagged compost and its in the garden…do the pyralids continue on ad infinitum? I now know why my tomatoes were all curled last year.
    Thanks

    • Good to know – even if it is sad news. The best treatment is sunlight and soil life, who are I feel super forgiving of all our insensitive, uncaring human ways (the compost maker not you that is) Uncover the soil if its mulched, drenched it in EM and leave it to nature. You can test it by doing a grow test as per the bottom of the article. If there are still signs of curling in your test seedlings then grow a mustard greencrop. Keep testing until the all clear.

  3. Avon Lookmire says

    Asked my local supply yard today what’s in their compost and they told me they get it from paranui organics 😊 Sometimes the world just makes things easy and simple 😊

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